General Microbiology

Menaquinones were the only isoprenoid quinones found in 48 corynebacteria and actinomycete strains examined. Dihydromenaquinones having nine isoprene units were the main components isolated from Gordona, Mycobacterium, Corynebacterium bovis, Corynebacterium glutamicum and a strain labelled Nocardia farcinica, but dihydromenaquinones having eight isoprene units were characteristic of other Corynebacterium species and representatives of the ' rhodochrous' complex. Tetrahydromenaquinones having six and eight isoprene units were found in Nocardia strains and in a single strain of Micropolyspora brevicatena, which also contained mycolic acids similar in chain length to those of Nocardia. Menaquinones having nine isoprene units with from one to five double bonds hydrogenated were the main Components in Actinomadura madurae, Actinomadura pelletieri, Micropolyspora faeni, Oerskovia turbata and Streptomyces strains. Actinomadura dassonvillei strains had a characteristic pattern of di-, tetra-and hexahydromenaquinones with 10 isoprene units which was slightly different from the pattern in mixtures of similar quinones from Actinomyces israelii and A c t inom y ces viscosus . I 5 MIC I 0 0 222 M. D. COLLINS AND OTHERS 0 0

Four hundred and seventy-five strains, which included 394 type cultures of Streptomyces and representatives of 14 other actinomycete genera, were studied. Overall similarities of these strains for 139 unit characters were determined by the S,, and S, coefficients and clustering by the UPGMA algorithm. Test error and overlap between the phena defined were within acceptable limits. Cluster-groups were defined by the S,, coefficient at the 70.1 % similarity ( S ) level and by the S, coefficient at the 50% S-level. Clusters were distinguished at the 77.5% SsM and 63% S, S-levels. Groupings obtained with the two coefficients were generally similar, but there were some changes in the definition and membership of cluster-groups and clusters.

Cultures of Azotobacter chroococcum strain A6 were grown for 14 days in a nitrogen-deficient mineral medium, the supernatant fluid and bacteria extracted and examined by paper partition chromatography with two solvent systems which separate authentic gibberellin (GA 3) and indolyl-3-acetic acid (IAA). Gibberellin-like substances were not detected on the chromatograms examined under ultraviolet (u.v.) radiation, but were detected when chromatograms were cut into ten equal strips representing a sequence of RF values and the eluates tested in dwarf pea and lettuce hypocotyl bioassays. Certain eluates applied to the roots of tomato seedlings also altered the later growth of stems, leaves and flowers. The Azotobacter cultures contained three gibberellin-like substances, of which probably the dominant was one with an RF value similar to that of GA 3 ; the other two were not identified. The average concentration of gibberellin/ml. culture was 0.03 pg. GA 3 equivalent. The gibberellins in Azotobacter cultures probably cause the reported effects on plant development and yield when seeds or roots are inoculated with Azotobacter. Plant growth may also be affected by synthesis of further gibberellins in the root zone when the Azotobacter inoculum colonizes developing roots.

This is to certify that the work in the project report entitled "Analysis of two level and three level inverters" by Piyus Mohanty(10602010) and Saransh Sahoo 10602058) has been carried out under my supervision in partial fulfillment of the requirement for the degree of Bachelor of Technology in "Electrical Engineering" during session 2008-09 in the Department of Electrical Engineering, National Institute of Technology, Rourkela and this work has not been submitted elsewhere for a degree. Rourkela ACKNOWLEDGEMENTS With a deep sense of gratitude, I wish to express my sincere thanks to my guide, Prof. A.K.

Silver nanoparticles are nanoparticles which are in the range of 1 and 100 nm in size. Silver nanoparticles have
unique properties which help in molecular diagnostics in therapies and in devices which are used in several medical procedures.
The major methods used for silver nanoparticles synthesis are the physical and chemical methods. The problems with the
chemical and physical methods are that the synthesis is expensive and also have toxic substances absorbed onto them. To
overcome this, biological methods provides a feasible alternative. The major biological system involved in this is bacteria, fungi
and plant extracts. The major application of silver nanoparticles in the medical fields includes diagnostics application and
therapeutics application. The major and in most of the therapeutic application, it is the antimicrobial property that is being
majorly explored though the anti-inflammatory properties has its fair share of applications. Though silver nanoparticles are
used in many medical procedures and devices as well as in various biological fields, they have their drawbacks due to
nontoxicity. This review provides a comprehensive view on the mechanism of action, synthesis and its application.
Keywords: Silver nanoparticles, Antimicrobial action, nanoparticle synthesis.

Nisin production by Lactococcus lactis subsp. lactis NIZO 22186 was studied in batch fermentation using a complex medium. Nisin production showed primary metabolite kinetics: nisin biosynthesis took place during the active growth phase and completely stopped when cells entered the stationary phase. A stringent correlation could be observed between the expression of the prenisin gene (nisA) and the synthesis of the post-translationally enzymically modified and processed mature nisin peptide. Moreover, it seemed likely that nisin had a growth control function. A physiological link is proposed between sucrose fermentation capacity and nisin production ability. Carbon source regulation appears to be a major control mechanism for nisin production.

This investigation aimed at determining the cyanide and starch contents of different species of
cassava grown in Abia State. Samples of cassava tubers were purchased from the local market
and identified by a taxonomist from the National Root Crops Research Institute, Umudike, Abia
State. In this study, the cyanide levels obtained were less than 100 mg/kg for both sweet and bitter
cassava. The lower concentration of cyanide obtained from this survey, could have been
influenced by the season of harvest (rainy season) in Nigeria. Of the six species analyzed, “0581”
recorded the highest in cyanide content with 62.57 ± 0.10 mg/kg, followed by “30211” with 59.55 ±
0.19 mg/kg. Sweet cassava (0505) recorded the least with 36.65 ± 0.16 mg/kg cyanide. On the
starch content, 21.70 ± 0.10% was obtained from “30572”, followed by “8083” with 20.62 ± 0.11%
and “30211” had the least starch content with 17.48 ± 0.02%. Both Starch (%) and HCN (mg/kg)
are statistically significant (p-value < 0.001) in the means for the various species of cassava under
study. However, from the posthoc test, there is no significant difference between species 30211
and 0581. The other species are significantly different at 5% level. However, all the species of cassava tested had cyanide above the recommended level (10 mg/kg). Consumption of these
cassava species unprocessed/inadequately processed would lead to serious health challenges
and therefore, efforts are required to reduce cyanide content at least to the recommended level.

A collection of 426 Haemophilus strains isolated from people with infectious diseases and from the normal flora of mucous membranes in humans and various animal species was studied in an attempt to revise and improve the taxonomy of the genus Haemophilus. The examinations included the determination of a number of biochemical and physiological properties, of which several had not previously been applied to the taxonomy of haemophili. The resulting data reavealed many hitherto unrecognized characters of taxonomic significance and several of the species can now be more accurately defined. The classification presented is supported by the DNA base composition of a large number of representative strains. A diagnostic key to the different taxa is presented. Haemophilus influenzae and H. parainfluenzae have been subdivided into a number of biotypes. It is possible to demonstrate a relationship between the individual biotypes of H. influenzae and the origin of the strains assigned to them. T...

Nitrogenase activity in the rhizosphere of a grass, Paspalum notatum, and its associated soil was measured by the reduction of acetylene. Roots of the cultivar ' batatais' colonized by Azotobacter paspali, when taken from the soil, produced I to 32 nmol C,H,/g dry wt/h, whereas the cultivar 'pensacola', which is not colonized by A . paspali, produced less than 0.5 nmol/g/h. There was a lag of 12 to 24 h before maximum, linear, rates of acetylene reduction were reached. Activity was almost completely inhibited in air or in the absence of 0, and was greatest at around PO, 0.04 atm. Activity of soil cores containing plants with leaves attached was little affected by PO, and showed no lag. Soil-plant cores maintained in a 16 h day+8 h night showed no diurnal fluctuation in activity; as the dark period was extended, activity decreased but was restored on returning plants to the light. Roots and rhizomes had most activity, the soil very little and aerial parts none. Washing the roots removed less than half the activity. Disturbance of soil-plant cores decreased activity. The soil next to the root surface contained most A. paspali; more were associated with active plants than with less active plants.

Arginyl- and lysyl-tRNA synthetases copurify throughout a six-step chromatographic procedure resulting in a purification of 605- and 559-fold, respectively. The purified enzymes were estimated to be 98% pure with a stoichiometry of 1:1 from acrylamide gel electrophoresis under denaturing conditions. On the basis of a native molecular weight of 285000 calculated from s20,w, Rs, and V and subunit molecular weights of 73000 and 65000 obtained by sodium dodecyl sulfate gel electrophoresis, the synthetases appear to exist as a tetramer. The tetrameric structure was also supported by cross-linking studies. These results are consistent with an alpha 2 beta 2 structure, but an alpha beta structure has not been ruled out.

Thirty-two strains originally identified as Lactobacillus acidophilus and L. gasseri were screened for their taxonomic homogeneity by SDS-PAGE of whole-cell proteins. After numerical comparison of the resulting protein electrophoretic fingerprints, two well-delineated clusters were detected. The majority of the strains grouped in one electrophoretic cluster, which contained the type strain of L. acidophilus and corresponds to DNA group A1 of Johnson, Bacteriology 30, 53-68). Another cluster corresponded to DNA group B. It contained two subclusters, which agreed perfectly with DNA subgroups B l (L. gasseri) and B2 (A. johnsonii), respectively. The 23s rRNA genes were partially sequenced and 23s-rRNA-targeted oligonucleotide probes were designed for identification of DNA groups Al, B1 and B2. Probe Lbg reacted with all strains of electrophoretic cluster B1 (L. gasseri), probe Lbj hybridized with strains of cluster B2 (L. johnsonii) and probe Lba with strains of cluster A1 (authentic L. acidophilus). The probes were successfully used for the identification of strains belonging to the respective species. The phylogenetic relationship of a representative of L. johnsonii was determined by comparative sequence analysis of the 16s rRNA genes. It is very closely related to L. gasseri.

SUMMARY: The immediate effects of externally added alcohols on CO 2 production and O 2 consumption of suspensions of washed, aerated baker&#x27;s yeast were studied by stopped-flow membrane inlet mass spectrometry. Glucose-supported fermentation was progressively ...

Zobo drink is an indigenous non-alcoholic drink made from hot water roselle calyces of Hibiscus
sabdariffa. The drink has gained wide acceptance, as it is consumed by several millions of people
from different socio-economic classes and background in West African sub-region. The greatest
limitation for large-scale production of zobo drinks is the rapid deterioration of the drink. Its shelf-life
is approximately 24 hours after production, if not refrigerated. The effect of lime juice on the
microorganisms associated with zobo drink was investigated. Zobo drink was prepared by
maintaining the appropriate hygienic standards. Microbiological analysis was carried out on the
prepared sample, before treatment with lime juice, to determine its effect on the microbial quality of
the drink. The mean total coliform count from the prepared sample was 0.1 x 10-4 cfu/mL, aerobic
bacterial count was 0.2 x10-4 cfu/mL and the fungal count was 0.4 x 10-4 cfu/mL. Microorganisms
isolated from the prepared sample include Staphylococcus spp, Lactobacillus spp, Bacillus spp and
Penicillium spp. The antimicrobial effect of the lime juice on the different isolates showed significant
zone of inhibition even at 6.25% concentration. The total coliform and aerobic bacterial count
generally decreased in value and showed no growth at 50-100% concentrations of lime juice for 3
days and 75-100% concentrations for 5 days. The findings from this study showed that lime juice can be used as natural preservative to prolong the shelf- life of zobo drink for a period 5 days under
normal room temperature.

Partial 16s ribosomal ribonucleic acid sequences of five Aevococcus-like organisms originally isolated from patients with urinary tract infections were determined using reverse transcriptase in order to clarify their taxonomic position. Analysis of the sequence data revealed that the clinical isolates represent a hitherto unknown line of descent within the genus Aerococcus. A new species, Aerococcus urinae, is proposed for these isolates. The type strain is NCFB 2893.

For the isolation of blue-green algae from soil and fresh water, temperature is a selective factor of major importance. In a nutritionally non-selective mineral medium, which at 25" supported growth of blue-green algae and of many eucaryotic algae, the development of eucaryotic algae was almost completely suppressed by incubation at 35". Both the number and variety of blue-green algae recoverable at 35" were greater than those recoverable from parallel cultures incubated at 25". When a combined-nitrogen source was omitted from the enrichment medium, only blue-green algae developed at both 25" and 35" ; the microflora consisted exclusively of heterocyst-forming filamentous types, other groups of blue-green algae being eliminated.

One hundred and fifty-six strains of Serratia and related bacteria including representatives of Enterobacter liquefaciens, Enterobacter cloacae, Enterobacter aerogenes, Erwinia carotovora, Erwinia chrysanthemi, Erwinia herbicola and Erwinia nimipressuralis were studied using 223 morphological, physiological, biochemical and carbon source utilization tests. The results were subjected to computer analysis. At the 80% similarity level all strains, except two, grouped into eight phenons representing: (A) Serratia marcescens with the neotype CCM303 (ATCCI3880); (B) S. marinorubra with the monotype NCTC10912 (ATCC27614); (CI) S. liquefaciens with the type ATCCI4460; (C2) S. plymuthica with the monotype CCM640 (ATCC183); (D) Erwinia herbicola with the neotype of Enterobacter agglomerans NCTC9381; (E) Enterobacter cloacae with the neotype NCTCI0005 and Erwinia nimipressuralis; (F) Erwinia carotovora with the type ATCC495, Erwinia atroseptica and Erwinia chrysanthemi; (G) Klebsiella mobilis with the neotype NCTCI0006. At the 70% similarity level the phenons formed two groups: (A, B, CI, C2) and (D, E, F, G). The following conclusions were drawn. (I) There are three species of enterobacteria producing prodigiosin: S. marcescens, S. plymuthica and S. marinorubra. (2) There are four species of Serratia, one colourless (S. liquefaciens). (3) Subphenons (biovars) are described within the four species of Serratia. (4) Non-pigmented wild-type strains of S. marcescens can generally be differentiated from pigmented strains by characters other than pigmentation, because subphenons are homogeneous with respect to pigmentation. This survey raised some problems of nomenclature because old descriptions could be found that could loosely fit the present phenons. Comparison with an authentic culture was considered to be the most objective way of identifying these phenons with earlier named species.

Using the five therapeutic oxicams 1–5, we showed that isosteric replacements result in remarkable changes in the physicochemical and structural properties of congeners. Thus, the acidity of the phenolic OH group is relatively higher in the oxicams containing a pyridinyl moiety, i.e. in piroxicam (1), tenoxicam (2), and lornoxicam, (3), due to their zwitterionic nature. This consequently influences their lipophilicity profile at different ionization states. Furthermore, partitioning behaviour in octan-l-ol/H2O and heptane/H2O systems suggests an internal H-bond between the enolic OH and the amide CO group. The anionic oxicams readily partition into the octanol phase at pH 7.4 and not at all into the heptane phase. Only the partition coefficients of oxicams measured in the heptane/H2O system, but not in the octanol/H2O system, correlate with their transfer across the blood-brain barrier. This implies that only the neutral form of oxicams crosses the blood-brain barrier.

Phosphofructokinase I1 (PFK 11) from Trichodevma veesei was partially purified (247-fold). The calculated K,,, values for fructose 6-phosphate and ATP were 0.7 mM and 40 PM, respectively. Upon incubation in the presence of [Y-~~P]ATP, the enzyme formed a radioactive phosphoprotein with molecular mass of 67 kDa in autoradiography analysis after SDS-PAGE. Upon incubation in the presence of ATP-Mg and the catalytic subunit of CAMPdependent protein kinase, its activity was not modified. The same result was obtained when a cell-free extract of T. veesei was incubated with ATP-Mg and CAMP. 2,4-Dinitrophenol caused a transient rise in cAMP levels in the fungal cell. These results provide evidence that the fructose 2,6-bisphosphate level in T. reesei is independent of cAMP concentrations and not related to a CAMP-dependent mechanism, but to the availability of substrate fructose 6-phosphate.

Streptococcus pyogenes, S. equinus, S. bovis, S. saliuarius, S. sanguis, S. mutans, S. rattus, S. cricetus, S. lacris, S. rafinolactis and Enterococcus jaecalis have been characterized by oligonucleotide cataloguingof their 16s ribosomal RNA. All the organisms form a loose but coherent group that is phylogenetically equivalent to those of lactobacilli, bacilli, the Brochothrixand Listeria group, and related taxa that constitute one of several sublines within the 'Clostridium' branch of Grampositive eubacteria. Within the Streptococcus-Enterococcus group, organisms fall into three moderately related clusters defined by Enterococcus, the lactic acid streptococci and streptococci of the pyogenic and oral groups, respectively.

The DNA and protein content of individual Escherichia coli cells were measured at a rate of 10(4) cells per second with a sensitive microscope-based flow cytometer. DNA and protein were quantified by measuring the fluorescence from cells stained with a combination of the DNA-binding drugs Mithramycin and ethidium bromide and by scattered light, respectively. Separate experiments demonstrated that the light scatter signal was proportional to protein content. Dual parameter histograms (fluorescence/scattered light) of bacterial cultures gave detailed pictures of changes dependent upon the growth conditions and of the cell cycle kinetics. Effects of antibiotics could be readily detected and characterized after a few hours. The results demonstrate that flow cytometry is a promising method for application in experimental and clinical microbiology.

Synthesis of chitinase and chitosanase by the entomopathogenic fungus Metarhizium anisopliae is regulated by products of chitin and chitosan degradation through an inducer-repressor mechanism. Slow-feeding with sugars or alanine (about 20 pg ml-l h-I) in a carbon deficient medium to prevent catabolite repression (restricted cultures) demonstrated that the most effective inducers of chitinase and chitosanase were the principal monomeric constituents of chitin (N-acetylglucosamine) and chitosan (glucosamine) respectively. Increasing the rate of release of N-acetylglucosamine decreased chitinase synthesis by about 87 % while causing a sevenfold increase in growth. In batch cultures high chitinase activities were present only in chitin-containing medium. There was a negative correlation between accessibility and amount of chitin substrates, levels of free N-acetylglucosamine in culture fluids and chitinase production. Addition of carbohydrates, lipid or proteins to chitin-grown cultures repressed chitinase production. Basal levels of chitinase were produced in non-inducing media. Production of chitobiase ( N-acetylglucosaminidase) was enhanced from high basal levels by amino sugars, but was less inducible and less susceptible to catabolite repression than chitinase.

A polymerase chain reaction (PCR) using heat-stable Taq polymerase is described for the specific detection of Mycobacterium leprae, the causative agent of leprosy. A set of primers was selected on the basis of the nucleotide sequence of a gene encoding the 36 kDa antigen of M. leprae. With this set of primers in the PCR, M. leprae could be detected specifically with a detection limit approximating one bacterium. This PCR appears to meet the criteria of specificity and sensitivity required for a useful tool in epidemiology and eventually for the control of leprosy.

Gold-labelled rabbit antiserum was used to demonstrate that a cuticle-degrading protease (Pr 1) is produced by Metarhizium anisopliae during penetration of host (Manduca sexta) procuticle. The protease was secreted by infection structures (appressoria) on the cuticle surface and by the penetrant hyphae within the cuticle. Penetration of the procuticle was by a combination of enzymic degradation and mechanical pressure. Initially Prl was confined to the immediate vicinity of the fungal structures; however the enzyme diffused throughout the cuticle during later stages of pathogenesis. When hyphae were labelled during growth in culture under conditions conducive to rapid synthesis of Prl, gold particles distributed over the fungal cell wall, indicating binding of Prl to hyphae.

A new serotype (h) of Streptococcus mutans was isolated from the dental plaque of monkeys (Macaca fascicularis). Serotype h strains fermented mannitol and melibiose but not sorbitol or raffinose, failed to hydrolyse aesculin and arginine, did not produce hydrogen peroxide and were unable to grow in the presence of bacitracin at 2 units ml-l. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of whole-cell proteins showed serotype h strains to be closely related to strains of genetic group I11 (i.e. serotypes d and g). The serotype-specific antigen of serotype h contained glucose and galactose but was antigenically distinct from the polysaccharide antigens of serotypes a, d and g. Serotype h strains preferentially colonized developmental grooves of teeth and the proportion of serotype h in the plaque flora was greater in monkeys fed a sucrose-rich diet than in monkeys fed a starch-based diet. A serotype h strain was cariogenic for germ-free rats fed a high-sucrose diet, and serotype h strains appear to be implicated in the caries process in monkeys.

The polymerase chain reaction (PCR) was used to amplify small-subunit ribosomal DNA from the anaerobic ciliated protozoon Metopus pdaeformis, and from its uncultured endosymbiotic bacteria. This was accomplished directly from total DNA extracted from protozoa without prior isolation or enrichment for symbiont cells. The double-stranded amplification products were precipitated and directly sequenced using the linear PCR reaction. Fluorescent oligonucleotide probes were designed and used in whole-cell hybridizations to provide direct visual evidence that the sequences originated from the host ciliate and from the endosymbiont. Phylogenetic analysis of the Metopus pdaeformis sequence consistently placed it as a deep-branching lineage near the root of the ciliate tree. However, the present data were insufficient to resolve the detailed relationship between Blepharisma and Metopus and thus to determine if the heterotrichs are mono-or paraphyletic. Phylogenetic analysis of the symbiont partial sequence clearly demonstrated that it is an archaeobacterium and that it is closely related to, but distinct from, Methanobacterium formicicum.

Out of 22 Enterobacter phages investigated, nine were found to be suitable for phage typing based on their different lytic spectra on 398 strains of Enterobacter spp. isolated from milk powder and other foods. These phages were compared on the basis of morphology, protein composition, restriction endonuclease patterns and DNA-DNA hybridization. Two phages (WS-EP19, WS-EP13) belonged to the Podoviridae family (morphotype C1), and three (WS-EP20, WS-EP26, WS-EP28) were classified as Siphoviridae (morphotype B1). The other four phages were Myoviridae of the morphological groups A1 (WS-EP57) and A2 (WS-EP32, WS-EP94, WS-EP96). SDS-PAGE revealed individual protein profiles for each phage, which corresponded to different restriction enzyme fragment patterns. DNA-DNA hybridization demonstrated the close relationship of phages WS-EP20 and WS-EP26, and of WS-EP94 and WS-EP96. In general, a good correlation was found between groupings obtained with the various methods. The nine phages could b...

Enrichment and elective culture for methylotrophs from sediment of the River Thames in central London yielded a diversity of pure cultures representing several genera of Gram-negative and Gram-positive bacteria, which were mainly of organisms not generally regarded as typically methylotrophic. Substrates leading to successful isolations included methanol, monomethylamine, dimethylamine, trimethylamine, methanesulfonate and dimethylsulfone. Several isolates were studied in detail and shown by their biochemical and morphological properties and 16S rRNA gene sequencing to be Sphingomonas melonis strain ET35, Mycobacterium fluoranthenivorans strain DSQ3, Rhodococcus erythropolis strain DSQ4, Brevibacterium casei strain MSQ5, Klebsiella oxytoca strains MMA/F and MMA/1, Pseudomonas mendocina strain TSQ4, and Flavobacterium sp. strains MSA/1 and MMA/2. The results show that facultative methylotrophy is present across a wide range of Bacteria, suggesting that turnover of diverse C1-compounds is of much greater microbiological and environmental significance than is generally thought. The origins of the genes encoding the enzymes of methylotrophy in diverse heterotrophs need further study, and could further our understanding of the phylogeny and antiquity of methylotrophic systems.

During germination, Streptomyces antibioticus arthrospores passed through three stages : darkening, swelling and germ tube emergence. The first stage, darkening, whose main features were a decrease in absorbance and a loss of refractility, only required exogenous divalent cations (Ca2+, Mg2+ or Fe2+) and energy that can be obtained from the spore reserves. This stage was blocked by agents that inhibit ATP formation but not by antibiotics that inhibit macromolecular synthesis. The second stage, swelling, needed an excgenous carbon source and was not blocked by mitomycin C. In this stage, the spores exhibited the highest cytochrome oxidase and catalase activities and respiratory quotient. The last stage, germ tube emergence, required additional carbon and nitrogen sources. Ammonium compounds were superior to nitrate. Dry weight remained constant during the stages of darkening and swelling, with a rapid increase from the moment of germ tube emergence. Optimum pH and temperature for germination were 8.0 and 45 "C, respectively. Heat treatment (55 "C for 10 min) had no effect on germination.

This study had two objectives: to determine the number of (phenotypic) ciliate species co-existing in 1 m2 of sandy river sediment at a maximum temperature of 4 "C; and to determine the ecological mechanism(s) facilitating their co-existence. The ciliate community was diverse (65 species [8 of which are new], belonging to 50 genera, from 17 orders). The sediment supported a superficial mat of diatoms (> 30 species). These served as food for at least 16 ciliate species. The size frequency distribution of ingested diatoms was almost identical to that for the diatoms in the sediment: thus the probability of a diatom being ingested appears to be a simple function of its relative abundance. Two factors were probably important for the co-existence of ciliate species : wide variation in cell size and shape enabled them to occupy most habitats; and they deployed a variety of feeding mechanisms to consume the variety of microbial food types. Taken as a whole, the ciliate community was capable of feeding on all microbes, including other protozoa, up to a size of about 80 pm. Considering the broad diversity of ciliate habitats available within 1 m2, the importance of physical transport processes in the river basin, and the known cosmopolitan distribution of many ciliate species, it is believed likely that the species richness we recorded is representative of the expanse of sandy sediment in this river, on this occasion. 0001-8305 0 1993 SGM

The phospholipid ester-linked fatty acids were examined in four Desulfobacter strains (2ac9, AcBa, 3ac 10 and 4acl l), a Desulfobacter-like 'fat vibrio' (AcKo) and Desulfotomaculum acetoxidans (5579, which are all sulphate-reducing bacteria that oxidize acetate. A thermophilic sulphate reducer, Desulfovibrio thermophilus, and two sulphur-reducing bacteria, Desulfuromonas acetoxidans (1 1070) and a Cumpylobacter-like spirillum (5175), were also studied. The Desulfobacter spp. were characterized by significant quantities of 1 0-methylhexadecanoic acid. Other 10-methyl fatty acids were also detected in Desulfobacter spp. No 10-methyl fatty acids were detected in the other organisms examined, supporting the use of 10-methylhexadecanoic acid as a biomarker for Desulfobacter, High levels of cyclopropyl fatty acids, including two isomers of both methylenehexadecanoic (cyl7 : 0) and methyleneheptadecanoic (cyl8 : 0) acids, were also characteristic of Desulfobacter spp. The influence of the volatile fatty acids (VFA) propionate, isobutyrate, isovalerate and 2-methylbutyrate on the lipid fatty acid distribution was studied with two Desulfobacter strains (2ac9, AcBa) and Desulfotomaculum acetoxidans. Although these sulphate reducers cannot oxidize the VFA, their presence in the acetate growth medium caused a shift in the fatty acid distribution in favour of odd-numbered and branched chains by apparent direct incorporation into the fatty acids as chain initiators. The Desulfobacter strains were distinguished from other sulphide-forming bacteria by the percentage of unsaturated and the percentage of branched fatty acids. ' Abbreviations: FAME, fatty acid methyl esters; VFA, volatile fatty acids. 0001-2949 0 1986 SGM Downloaded from www.microbiologyresearch.org by IP: 54.160.78.180 On: Sat

The distribution of the arginine succinyltransferase pathway was examined in representative strains of Pseudomonas and related bacteria able to use arginine as the sole carbon and nitrogen source for growth. The arginine succinyltransferase pathway was induced in arginine-grown cells. The accumulation of succinylornithine following in vivo inhibition of succinylornithine transaminase activity by aminooxyacetic acid showed that this pathway is responsible for the dissimilation of the carbon skeleton of arginine. Catabolism of citrulline as a carbon source was restricted to relatively few of the organisms tested. In P. putida, P . cepacia and P . indigofera, ornithine was the main product of citrulline degradation. In most strains which possessed the arginine succinyltransferase pathway, the first step of ornithine utilization as a carbon source was the conversion of ornithine into succinylornithine through an ornithine succinyltransferase. However P . cepacia and P. putida used ornithine by a pathway which proceeded via proline as an intermediate and involved an ornithine cyclase activity.

Exopolysaccharide formation by Pseudomonas NCIBI I 264 in a single-stage continuous culture was maximal under nitrogen limitation with excess carbohydrate substrate at 30 -t I "C and pH 7-0 _+ 0.1. Polysaccharide production was not enhanced by phosphate limitation but was dependent on the dilution rate. Steady states were maintained for up to 500 h without deterioration of the culture or the development of mutant strains. The efficiency of conversion of the glucose substrate utilized into exopolysaccharide by the chemostat cultures was as high as 73 %.

The production of pectinase was studied in Neurospora crassa, using the hyperproducer mutant exo-1, which synthesized and secreted five to six times more enzyme than the wild-type. Polygalacturonase, pectin lyase and pectate lyase were induced by pectin, and this induction was glucose-repressible. Polygalacturonase was induced by galactose four times more efficiently than by pectin; in contrast the activity of lyases was not affected by galactose. The inducing effect of galactose on polygalacturonase was not glucose-repressible. Extracellular pectinases were separated by ion exchange chromatography. Pectate and pectin lyases eluted into three main fractions containing both activities; polygalacturonase eluted as a single, symmetrical peak, apparently free of other protein contaminants, and was purified 56-fold. The purified polygalacturonase was a monomeric glycoprotein (38% carbohydrate content) of apparent molecular mass 36.6-37.0 kDa (Sephadex G-100 and urea-SDS-PAGE, respectivel...

Cells of Saccharomjces cerevisiae exhibiting respirative glucose metabolism in continuous culture were able to use ethanol as a co-substrate. The ethanol uptake rate was dependent on the residual respirative capacity of the cells. The activities of gluconeogenic enzymes and of malate dehydrogenase were higher in cells degrading glucose respiratively than in cells metabolizing glucose respiro-fermentatively, but were lower than in cells growing on ethanol only. The pattern of distribution of the mitochondria1 cytochromes was similar but the differences were less distinct. In synchronously growing cells, the activities of gluconeogenic enzymes and of malate dehydrogenase oscillated, with activities increasing during the budding phase. The increase was preceded by the appearance of ethanol in the culture medium.

A reference collection of 72 strains representing 37 serovars of Salmonella subspecies I has been established for use in research on genetic and phenotypic variation in natural populations. Included are isolates of the host-adapted serovars S. choleraesuis, S. dublin, S. gallinarum, S. paratyphi A , S. paratyphi B, S. paratyphi C, S. pullorum, S. sendai, S. typhi and S. typhisuis, as well as strains of S. enteritidis, S. typhimurium, and other commonly recovered serovars with broad host ranges. The isolates were characterized by enzyme electrophoresis for allelic variation in 25 chromosomal genes and represent 71 distinctive multilocus genotypes (electrophoretic types or ETs). Genetic relationships among the ETs are indicated in an evolutionary tree constructed by the neighbourjoining method from a matrix of Nei's standard genetic distance.

This study investigated the effect of cooking time on starch and cyanide contents of freshly
harvested cassava tubers used for tapioca production. Tapioca is a cassava meal commonly
consumed in most part of the world and prepared from freshly harvested cassava tubers. The
cassava tubers used for tapioca production are first boiled and sliced, before soaking in water
overnight. The cassava tubers used for this study were harvested from the eastern farm of National
Root Crops Research Institute, Umudike in Abia State, Nigeria. Some freshly harvested cassava
tubers were subjected to 90 minutes cooking in clean water and at intervals of 15 minutes, samples
were collected for starch and cyanide analyses. The result showed that increase in cooking time
decreased the starch and cyanide contents of the cassava samples. Starch was reduced from
13.37% to 4.65% for every 2 g of starch tuber given 65.22% reduction after 90 minutes. The cyanide
content was reduced from 36.65±0.16 to 2.49±0.08 mg/kg after 90 minutes of boiling, given a 93.2%

Two novel, thermophilic piezophiles, capable of chemolithoautotrophic growth, are successfully cultivated and isolated from a black smoker chimney at the TAG field (Mid Atlantic Ridge: MAR) by using a piezophilic cultivation technique. Both strains (strains 106 and 108) represent dominant cultivated populations of the microbial communities in the chimney surface habitat. Strain 106 represents typically thin, long spiral cells under the piezophilic growth condition but short bent cells under the non-piezophilic condition. It is a strictly chemolithoautotrophic gammaproteobacterium using reduced sulfur compounds as the electron donors, and nitrate and O 2 as the electron acceptors. Based on the 16S rRNA gene sequence, strain 106 would represent a novel genus of the previously uncultivated group (Symbiont Group I; a potentially novel family) within the Gammaproteobacteria, and 'Thioprofundum lithotrophica' gen. nov., sp. nov. is proposed. Strain 108 is a short, oval rod at any of the growth pressures. It is a facultative chemoautotroph, capable of both chemolithoautotrophic growth with H 2 and S oxidations and organotrophic growth with complex organics or organic acids using nitrate and O 2 as the electron acceptors. The chemolithoautotrophic growth is strictly piezophilic and under the organotrophic growth condition, it grows at conventional pressures (0.1 MPa). Strain 108 is phylogenetically distinctive from any of the previously described genera of the family Rhodobacteraceae within the Alphaproteobacteria, and 'Piezobacter thermophilus' gen. nov., sp. nov. is proposed. The piezophilic cultivation technique can be a powerful tool to isolate and characterize the previously uncultivated phylotypes in the deep-sea hydrothermal vent environments. et al., 2008a). Nevertheless, all the deep-sea piezophilic chemolithoautotrophs studied 60 so far were initially isolated by the cultures under the conventional gas pressures (up to 61 0.4 MPa), and none of the chemolithoautotrophs is obtained by a high-pressure culture 62 directly from a deep-sea habitat. 63 Direct piezophilic enrichment from deep-sea and deep subsurface microbial 64 communities would be advantageous to obtain the numerically predominant or the 65 functionally significant microbial populations in the in situ habitats. This is not only 66 is located at water depth of between 3620 and 3660 m and is among the world deepest 87 hot hydrothermal systems. The H 2 -and/or sulfur-oxidizing chemolithoautotrophs are 88 one of the most predominant microbial populations in the global deep-sea hydrothermal 89 environments and a diversity of Aquificae and Epsilonproteobacteria members have 90

Two strains of Legionella pneumophila serogroup 1 monoclonal subgroup Pontiac were grown for the first time in continuous culture using a chemically defined medium. The influence of temperature on physiology and morphology was investigated by fixing the growth rate (equal to the dilution rate, D ) at 0.08 h-' and controlling the pH and dissolved oxygen concentration of the culture. Serine provided the principal source of carbon and energy but growth was limited by tyrosine. The bacterium behaved as a microaerophile in this medium, with maximal growth occurring at 0.31 (mg 0,) 1-(equivalent to a dissolved oxygen tension of 4 % (vlv) air saturation at 30 OC). The cultures consisted of flagellated, short rods at 24 OC, but exhibited an increased level of pleomorphism and the loss of flagella as the temperature was increased to 37 "C. The presence of intracellular granules was noted, and their abundance was temperature-dependent. Polyhydroxybutyrate was present in L. pneumopliila, and the proportion of the cell dry weight that it accounted for varied with temperature, being maximal at 24 O C . The ratio of saturated to unsaturated fatty acids in the cells decreased as the temperature was reduced towards 24 OC, so as to maintain membrane fluidity at low growth temperature. 0001-7594 0 1992 SGM

Microbial cells in suspension were added to two soils. After drying, the degree of aggregation and stability of the aggregates to water was estimated by adding water, shaking and measuring turbidimetrically the particles remaining in suspension. In a silt loam (Hamble series), Azotobacter chroococcum, Lipomyces starkeyi and Pseudoinonas sp. all promoted the stabilization of aggregates, this being related to the number of cells added, but Mucor hiemalis inhibited the process. In a clay soil (Denchworth series), Mucor hiemalis and Pseudomonas sp. both promoted stabilization. The stabilization of the silt loam by Lipomyces starkeyi was also produced by the polysaccharide extracted from the cell.

Arthrobacter species, isolated from the leaf cavities and the microsporocarps of the aquatic fern species Azolla pinnata and Azolla filiculoides, produced indole-3-acetic acid (IAA) in culture when the precursor tryptophan was added to the medium. No IAA production was detected in the absence of tryptophan. Maximum IAA formation was obtained in the first 2 d of incubation. Part of the tryptophan was transformed to N alpha-acetyl-L-tryptophan.

Cells of mucoid and non-mucoid Pseudomonas aeruginosa in colonies were at least onethousandfold less sensitive to the antibiotics tobramycin or cefsulodin than were cells of the same bacteria in dispersed suspension. We did not detect any difference between the mucoid form and the non-mucoid form in the antibiotic sensitivity of colonies, from which we infer that the exopolysaccharide of the mucoid form does not contribute to colony-resistance by forming a barrier to antibiotic diffusion. Mathematical models were constructed in order to estimate timecourses of penetration of tobramycin and cefsulodin into biofilms and microcolonies of mucoid and non-mucoid P. aeruginosa. For tobramycin penetration, adsorption of antibiotic to the exopolysaccharide of the glycocalyx and antibiotic uptake by cells were taken into account in the calculations. The longest time-period for the concentration of tobramycin at the base of a biofilm 100 prn deep to rise to 90% of the concentration outside the biofilm was predicted to be 2.4 h. For cefsulodin penetration, irreversible hydrolysis catalysed by p-lactamase was taken into account, using P-lactamase levels taken from the literature. The calculations predicted that the cefsulodin concentration at the base of a biofilm 100pm deep would rise to 90% of the external concentration in 29 s when the /I-lactamase was synthesized at the basal level. For a similar biofilm of bacteria synthesizing enhanced levels of fl-lactamase ('derepressed'), the concentration of cefsulodin at the base was calculated to rise to 41% of the external concentration in about 50s and then remain at that level. This was despite the fact that cefsulodin is a poor substrate for this P-lactamase.

A mutant of A . tumefaciens strain ~6~3 , carrying the R factor RP4, was able to transfer its TI plasmid to various avirulent Agrobacterium strains and to a strain of Rhizobium. Strains carrying the TI(~6s3) plasmid were selected by their ability to utilize octopine. The isolates were able to induce tumours and exclude phage API . The tumours induced on Kalanchoe daigremontiana were rough and contained