Showing papers in "Fems Microbiology Letters in 1992"
TL;DR: Conjugative transfer, in the apparent absence of plasmid DNA, of high-level vancomycin resistance from Enterococcus faecalis NCTC 12201 to Staphylococcus aureus B111 has been demonstrated and transfer of erythromycin and of chloramphenicol resistance has been achieved.
Abstract: Conjugative transfer, in the apparent absence of plasmid DNA, of high-level vancomycin resistance from Enterococcus faecalis NCTC 12201 to Staphylococcus aureus B111 has been demonstrated in vivo and in vitro. Selection of transconjugants on media containing erythromycin or chloramphenicol may result in the transfer of resistance to erythromycin, chloramphenicol, gentamicin, streptomycin and vancomycin though these are capable of separate transfer. Vancomycin resistance has not been transmitted from staphylococcus to staphylococcus though transfer of erythromycin and of chloramphenicol resistance has been achieved.
900 citations
TL;DR: In this article, a new method for accurate and easy measurement of denitrification in sediments is presented, in which the water overlying intact sediment cores was enriched with 15NO3− which mixed with the 14NO3 − of the natural sources of NO3− and the formation of unlabeled (14N14N) dinitrogen pairs was measured by mass spectrometry after a few hours incubation.
Abstract: A new method for accurate and easy measurement of denitrification in sediments is presented. The water overlying intact sediment cores was enriched with 15NO3− which mixed with the 14NO3− of the natural sources of NO3−. The formation by denitrification of single-labeled (14N15N) and double-labeled (15N15N) dinitrogen pairs was measured by mass spectrometry after a few hours incubation. Total denitrification including the formation of unlabeled (14N14N) dinitrogen could be calculated assuming random isotope pairing by denitrification of the uniformly mixed NO3− species. In contrast to previous approaches, by this method it is possible to measure denitrification of both NO3− diffusing from the overlying water and NO3− from nitrification within the sediment.
681 citations
TL;DR: Many fungi in the centre of the group of Fusarium and its teleomorphs were shown to be capable of reducing nitrite anaerobically to form nitric oxide (NO), nitrous oxide (N 2O), and/or dinitrogen (N2).
Abstract: Many fungi in the centre of the group of Fusarium and its teleomorphs were shown to be capable of reducing nitrite anaerobically to form nitric oxide (NO), nitrous oxide (N2O), and/or dinitrogen (N2). Several strains could reduce nitrate as well. Nitrous oxide was the major product of the reduction of nitrate or nitrite. Several fungi could also form N2. When [15]nitrite was used as substrate for the N2-forming dinitrification, 15N2O, 15NO, and 14N15N were obtained as the products. These results demonstrated that, unexpectedly, many fungi have denitrifying abilities. It was also shown that the fungal system contains a unique reaction, formation of a hybrid dinitrogen.
389 citations
TL;DR: A significantly improved method for the electroporation of plasmid DNA into Staphylococcus aureus is developed, and the highest transformation efficiency achieved with this procedure was 4.0 x 10(8) transformants per microgram ofplasmid pSK265 DNA.
Abstract: We have developed a significantly improved method for the electroporation of plasmid DNA into Staphylococcus aureus. The highest transformation efficiency achieved with this procedure was 4.0 x 10(8) transformants per microgram of plasmid pSK265 DNA. This represents a 530-fold improvement over the previously reported optimum efficiency of 7.5 x 10(5) transformants per microgram of plasmid DNA after electroporation of S. aureus cells [9]. Identical results were obtained when electrocompetent cells, which had been stored frozen at -80 degrees C, were used. The improved efficiency is due primarily to the use of a modified medium (designated as B2 medium) and secondarily to the use of 0.1-cm cuvettes. Several other plasmids (pI258, pMH109, and pSK270) were also electrotransformed into competent cells using our procedure, and for each plasmid, the transformation efficiency was significantly reduced compared to that observed when pSK265 DNA was used. With respect to plasmid pI258, the transformation efficiency was 3500-fold higher than that reported previously for transformation of this plasmid into S. aureus RN4220 [9]. The optimized electroporation procedure was less successful in transforming other staphylococci. Electrocompetent cells of S. aureus ATCC 29213 and S. epidermidis ATCC 12228 produced 5.5 x 10(5) and 5 x 10(3) transformants per microgram of pSK265 DNA, respectively.
389 citations
TL;DR: The kinetic parameters of CH4 oxidation (Km, Vmax, apparent threshold = Tha) were measured using different oxic soils (cultivated cambisol, forest luvisol, meadow cambiscus, paddy soil) both in a fresh state and after 3 weeks preincubation under high CH4 mixing ratios (20%).
Abstract: The kinetic parameters of CH4 oxidation (Km, Vmax, apparent threshold = Tha) were measured using different oxic soils (cultivated cambisol, forest luvisol, meadow cambisol, paddy soil) both in a fresh state and after 3 weeks preincubation under high CH4 mixing ratios (20%). The preincubation resulted in an increase of the most probable number of methanotrophic bacteria. In fresh soils, CH4 oxidation followed Michaelis-Menten kinetics with a low Km (30–51 nM CH4), low Vmax (0.7–3.6 nmol CH4 h−1g−1dw soil), and low Tha (0.2–2.7 ppmv CH4). In preincubated soils, CH4 oxidation exhibited biphasic kinetics in which two different CH4 saturation curves were apparently superimposed on each other. Eadie-Hofstee plots of the data showed two activities with different kinetic parameters: a high-affinity activity with low Km (13–470 nM CH4), low Vmax (2.1–150.0 nmol CH4 h−1g−1dw) and low Tha (0.3–4.1 ppmv CH4) being similar to the kinetic parameters in fresh soils; and a low-affinity activity with high Km (1740–27 900 nM CH4), high Vmax (270–3 690 nmol CH4 h−1g−1dw) and high Tha (11–45 ppmv CH4) being similar to the kinetic parameters known from methanotrophic bacteria. The low-affinity activity was also observed in a soil over a deep natural gas source which was permanently exposed to high CH4 mizing ratios (>5% CH4). Bacteria culturable as methanotrophs are probably responsible for the low-affinity activity which is typical for the soils exposed to high CH4 mixing ratios. However, the bacteria responsible for the high-affinity activity are still unknown. This activity is typical for the soils exposed to only ambient CH4 mixing ratios. Both high- and low-affinity activities were inhibited by autoclaving and by acetylene.
336 citations
TL;DR: Some interactions are of biotechnologic importance being relevant to metal removal, including microfossil formation, iron and manganese deposition, silver and uranium mineralisation, as well as resulting in transfer to other organisms via food chains.
Abstract: Metals are directly a n d / o r indirectly involved in all aspects of microbial growth, metabolism and differentiation. Many metals are essential, e.g. K, Na, Mg, Ca, Mn, Fe, Co, Ni, Cu, Zn, Mo, whereas others have no known essential biological function(s), e.g. AI, Ag, Cd, Sn, Au, Sr, Hg, T1, Pb. All these elements can interact with microbial cells and be accumulated as a result of physico-chemical mechanisms and transport systems of varying specificity, independent of, or directly and indirectly dependent on, metabolism [1-4]. Some of these processes are of global importance being components of major biogeochemical cycles, including microfossil formation, iron and manganese deposition, silver and uranium mineralisation, as well as resulting in transfer to other organisms via food chains [2,5-8]. Some interactions are of biotechnologicai importance being relevant to metal removal a n d / o r
303 citations
TL;DR: The results indicate that amplified rDNA restriction analysis is a simple and reliable tool for the identification of bacterial species.
Abstract: Ribosomal rRNA gene fragments (rDNA) encompassing the 16S rDNA, the 16S-23S rDNA spacer region and part of the 23S rDNA of 95 strains belonging to 13 well-described taxa of the eubacterial family Comamonadaceae (beta subclass of the Proteobacteria or rRNA superfamily III) were enzymatically amplified using conserved primers. The fragments of approximately 2400 base pairs were subjected to restriction analysis. Restriction fragment length patterns obtained with HinfI enabled us to distinguish 9 of the 13 taxa studied. Restriction with CfoI was necessary to differentiate Acidovorax delafieldii from A. temperans and Hydrogenophaga flava from H. pseudoflava. The results indicate that amplified rDNA restriction analysis is a simple and reliable tool for the identification of bacterial species.
266 citations
TL;DR: The production of branched chain-fatty acids is measured both in vitro and in vivo in order to estimate the contribution of protein to fermentation and suggest that protein fermentation could potentially account for about 17% of the SCFA found in the caecum, and 38% ofThe SCFA produced in the sigmoid/rectum.
Abstract: The importance of protein breakdown and amino acid fermentation in the overall economy of the large intestine has not been quantitated. We have therefore measured the production of branched chain-fatty acids (BCFA) both in vitro and in vivo in order to estimate the contribution of protein to fermentation.
In vitro batch-culture studies using human faecal inocula showed that short-chain fatty acids (SCFA) were the principal end products formed during the degradation of protein by human colonic bacteria. Approximately 30% of the protein broken down was converted to SCFA. Branched-chain fatty acids (BCFA) constituted 16% of the SCFA produced from bovine serum albumin and 21% of the SCFA generated when casein was the substrate. BCFA concentrations in gut contents taken from the human proximal and distal colons were on average, 4.6 and 6.3 mmol kg−1 respectively, corresponding to 3.4% and 7.5% of the total SCFA. These results suggest that protein fermentation could potentially account for about 17% of the SCFA found in the caecum, and 38% of the SCFA produced in the sigmoid/rectum. Measurements of BCFA in portal and arterial blood taken from individuals undergoing emergency surgery indicated that net production of BCFA by the gut microflora was in the region of 11.1 mmol day−1, which would require the breakdown of about 12 g of protein. These data highlight the role of protein in the colon and may explain why many colonic diseases affect mainly the distal bowel.
261 citations
TL;DR: It is proposed that nickel is ligated solely by amino acid residues of the large subunit and that the non-heme iron clusters are ligated by other cysteine-rich polypeptides encoded in the hydrogenase operons which are not necessarily homologous in either structure or function.
Abstract: The enzymology of the heterodimeric (NiFe) and (NiFeSe) hydrogeneses, the monomeric nickel-containing hydrogenases plus the multimeric F420-(NiFe) and NAD+-(NiFe) hydrogenases are summarized and discussed in terms of subunit localization of the redox-active nickel and non-heme iron clusters. It is proposed that nickel is ligated solely by amino acid residues of the large subunit and that the non-heme iron clusters are ligated by other cysteine-rich polypeptides encoded in the hydrogenase operons which are not necessarily homologous in either structure or function. Comparison of the hydrogenase operons or putative operons and their hydrogenase genes indicate that the arrangement, number and types of genes in these operons are not conserved among the various types of hydrogenases except for the gene encoding the large subunit. Thus, the presence of the gene for the large subunit is the sole feature common to all known nickel-containing hydrogenases and unites these hydrogenases into a large but diverse gene family. Although the different genes for the large subunits may possess only nominal general derived amino acid homology, all large subunit genes sequenced to date have the sequence R-X-C-X-X-C fully conserved in the amino terminal region of the polypeptide chain and the sequence D-P-C-X-X-C fully conserved in the carboxyl terminal region. It is proposed that these conserved motifs of amino acids provide the ligands required for the binding of the redox-active nickel. The existing EXAFS (Extended X-ray Absorption Fine Structure) information is summarized and discussed in terms of the numbers and types of ligands to the nickel and the various redox species of nickel defined by EPR spectroscopy. New information concerning the ligands to nickel is presented based on site-directed mutagenesis of the gene encoding the large subunit of the (NiFe) hydrogenase-1 of Escherichia coli. Based on considerations of the biochemical, molecular and biophysical information, ligand environments of the nickel in different redox states of the (NiFe) hydrogenase are proposed.
253 citations
TL;DR: The potential of PCR for detection and differentiation of C. gloeosporioides is discussed and a 450-bp fragment was amplified from as little as 10 fg of fungal DNA.
Abstract: An oligonucleotide primer (CgInt), synthesised from the variable internally transcribed spacer (ITS) 1 region of ribosomal DNA (rDNA) of Colletotrichum gloeosporioides was used for PCR with primer ITS4 (from a conserved sequence of the rDNA) to amplify a 450-bp fragment from the 25 C. gloeosporioides isolates tested. This specific fragment was amplified from as little as 10 fg of fungal DNA. A similar sized fragment was amplified from DNA extracted from C. gloeosporioides-infected tomato tissue. RAPD analysis divided 39 C. gloeosporioides isolates into more than 12 groups linked to host source and geographic origin. Based on the results obtained, the potential of PCR for detection and differentiation of C. gloeosporioides is discussed.
208 citations
TL;DR: Clay-adsorbed DNA was found to be still able, even after a strong DNaseI treatment, to artificially transform competent Escherichia coli cells, showing that persistance of DNA and gene transfer by genetic transformation may occur in soil.
Abstract: Numerous authors have investigated DNA relationships with sandy soil. A model composed of various DNAs adsorbed on montmorillonite clay was developed to assay enzyme (DNaseI) activity on clay-adsorbed nucleic acids. The extent of DNA adsorption was affected by the concentration and valency of the cations used (Mg2+, Ca2+, Na+), indicating a charge-dependent process. Calf thymus DNA was found to be highly adsorbed by smectite (up to 30 mg g−1 of dry clay). Adsorbed DNA was shown to be more resistant to degradation by DNaseI than free DNA. Experimental data with plasmid and short linear amplified (through polymerase chain reaction) DNA showed that protection against nucleases was only partial. Nevertheless, clay-adsorbed DNA was found to be still able, even after a strong DNaseI treatment, to artificially transform competent Escherichia coli cells. The results show that persistance of DNA and gene transfer by genetic transformation may occur in soil.
TL;DR: Isotopic and fluorimetric assays demonstrated that the qac genes code efflux systems that rely on proton motive force.
Abstract: Clinical isolates of Staphylococcus aureus carry various antiseptic and disinfectant resistance determinants (qac genes) on a variety of plasmids. The biochemistry and specificity of these resistance genes in S. aureus is the subject of this report. The qac genes were separated into two families on the basis of resistance profiles and DNA homology. Isotopic and fluorimetric assays demonstrated that the qac genes code efflux systems that rely on proton motive force.
TL;DR: A number of broad-host-range plasmids that allow the expression of the Escherichia coli lac operon from any cloned promoter, and the creation of 'in phase' fusions between lacZ and other cloned genes are developed.
Abstract: We have developed a number of broad-host-range plasmids that allow the expression of the Escherichia coli lac operon from any cloned promoter, and the creation of ‘in phase’ fusions between lacZ and other cloned genes. In a second series of constructions, the E. coli gal operon has been cloned into the broad-host-range vector and a plasmid carrying both the E. coli gal and lac genes is described. These plasmids have been transferred into Pseudomonas aeruginosa and Zymomonas mobilis and their effects on the utilisation of lactose and galactose have been investigated.
TL;DR: Short-period (40-50 min) synchronized metabolic oscillation was found in a continuous culture of yeast Saccharomyces cerevisiae under aerobic conditions at low-dilution rates, which may indicate new aspects of the control mechanism of glycogen metabolism and how respiration and ethanol fermentation are regulated togetherunder aerobic conditions.
Abstract: Short-period (40–50 min) synchronized metabolic oscillation was found in a continuous culture of yeast Saccharomyces cerevisiae under aerobic conditions at low-dilution rates. During oscillation, many parameters changed cyclically, such as dissolved oxygen concentration, respiration rate, ethanol and acetate concentrations in the culture, glycogen, ATP, NADH, pyruvate and acetate concentrations in the cells. These changes were considered to be associated with glycogen metabolism. When glycogen was degraded, the respiro-fermentative phase was observed, in which ethanol was produced and the respiration rate decreased. In this phase, the levels of intracellular pyruvate and acetate became minimum, ATP became high and intracellular pH at its lowest level. When glycogen metabolism changed from degradation to accumulation, the respiratory phase started, during which ethanol was re-assimilated from the culture and the respiration rate increased. Intracellular pyruvate and acetate became maximum, ATP decreased and the intracellular pH appeared high. These findings may indicate new aspects of the control mechanism of glycogen metabolism and how respiration and ethanol fermentation are regulated together under aerobic conditions.
TL;DR: The mature forms of the extracellular muramidase-2 of Enterococcus hirae and Streptococcus faecalis autolysin have very similar primary structures, illustrating the principle that protein molecules frequently are constructed from modules that are linked in a single polypeptide chain.
Abstract: The mature forms of the extracellular muramidase-2 of Enterococcus hirae and Streptococcus faecalis autolysin have very similar primary structures. Each consists of an active-site-containing N-terminal domain fused to a multiple-repeat C-terminal domain. Polypeptide segments occurring at equivalent places in these two bacterial wall lytic enzymes have homologues in two phage lysozymes and in three functionally unrelated proteins, illustrating the principle that protein molecules frequently are constructed from modules that are linked in a single polypeptide chain.
TL;DR: Chlorhexidine did not inhibit ATPase in intact cells of Escherichia coli K12 W1317i-, even at bactericidal concentrations, and ATP hydrolysis was greatest at the highest concentration (40 mg/l), even though no net uptake of substrate occurred.
Abstract: Chlorhexidine did not inhibit ATPase in intact cells of Escherichia coli K12 W1317i−, even at bactericidal concentrations, and ATP hydrolysis was greatest at the highest concentration (40 mg/l), even though no net uptake of substrate occurred. Like dinitrophenol and tribrominated salicylanilide, polymyxin and chlorhexidine collapsed the membrane potential at inhibitory concentrations. Membrane disruption, and not ATPase inactivation, is considered the lethal event in chlorhexidine action.
TL;DR: A protocol was devised which permitted the extraction of DNA from deep marine sediments up to 503 m below the sea floor and 16S rRNA gene sequences were amplified from the DNA by the polymerase chain reaction.
Abstract: A protocol was devised which permitted the extraction of DNA from deep marine sediments up to 503 m below the sea floor. These sediments have been laid down over the last 3 million years. 16S rRNA gene sequences were amplified from the DNA by the polymerase chain reaction. The details of the successful extraction and polymerase chain reaction methodology varied between samples from different depths. This emphasizes the attention to detail required to allow the diversity of bacteria in these deep sediments to be studied.
TL;DR: It is postulated that the heat-killed L. acidophilus LB cells inhibit diarrheagenic E. coli attachment by steric hindrance of the human enterocytic ETEC receptors.
Abstract: Diarrheagenic Escherichia coli (ETEC) bearing CFA/I or CFA/II adhesive factors specifically adhere onto the brush border of the polarized epithelial human intestinal Caco-2 cells in culture. Heat-killed Lactobacillus acidophilus strain LB, that adheres onto Caco-2 cells, inhibits diarrheagenic Escherichia coli adhesion in a concentration-dependent manner. Since the L. acidophilus does not express ETEC-CFA adhesive factors, it can be postulated that the heat-killed L. acidophilus LB cells inhibit diarrheagenic E. coli attachment by steric hindrance of the human enterocytic ETEC receptors.
TL;DR: Two new diazotrophic bacteria, Listonella anguillarum and Vibrio campbellii and one non-nitrogen-fixing bacterium, Staphylococcus sp.
Abstract: Two new diazotrophic bacteria, Listonella anguillarum and Vibrio campbellii , and one non-nitrogen-fixing bacterium, Staphylococcus sp., were isolated from the rhizosphere of mangrove trees. Strains of these newly-defined diazotrophs are known as pathogenic bacteria in fish and shellfish. During the purification of diazotrophic species from the entire rhizosphere population, N 2 -fixation of the bacterial mixtures decreased. When grown in vitro in mixed cultures, the non-fixing bacterium Staphylococcus sp. increased the nitrogen-fixing capacity of L. anguillarum by 17% over the pure culture; the nitrogen-fixing capacity per bacterial cell increased 22%. This interaction was not due to a change in O 2 concentration. Staphylococcus sp. decreased the nitrogen-fixing capacity of V. campbellii by 15%. These findings indicate that (i) other species of rhizosphere bacteria, apart from the common diazotrophic species, should be evaluated for their contribution to the nitrogen-fixation process in mangrove communities; and (ii) the nitrogen-fixing activity detected in the rhizosphere of mangrove plants is probably not the result of individual nitrogen-fixing strains, but the sum of interactions between members of the rhizosphere community.
TL;DR: The sulfur cycle in a microbial mat was studied by determining viable counts of sulfate-reducing bacteria, chemolithoautotrophic sulfur bacteria and anoxygenic phototrophic bacteria and determination of the vertical distribution of the potential rate of thiosulfate consumption under oxic conditions.
Abstract: The sulfur cycle in a microbial mat was studied by determining viable counts of sulfate-reducing bacteria, chemolithoautotrophic sulfur bacteria and anoxygenic phototrophic bacteria. All three functional groups of sulfur bacteria revealed a maximum population density in the uppermost 5 mm of the mat: 1.1 × 108 cells of sulfate reducers cm−3 sediment, 2.0 × 109 cells of chemolithoautotrophs cm−3 sediment, and 4.0 × 107 cells of anoxygenic phototrophs cm−3 sediment. Bacterial dynamics were studied by sulfate reduction rate measurements, both under anoxic conditions (dark incubation) and oxic conditions (incubation in the light), and determination of the vertical distribution of the potential rate of thiosulfate consumption under oxic conditions. Sulfate reduction rates in the top 5 mm of the sediment were 566 nmol cm−3 d−1 in the absence of oxygen, and 123 nmol cm−3 d−1 in the presence of oxygen. In the latter case, the maximum rate was found in the 5–10-mm depth horizon (361 nmol cm−3 d−1). Biological consumption of amended thiosulfate was rapid and decreased with depth, while in the presence of molybdate, thiosulfate consumption decreased to 10–30% of the original rate.
TL;DR: The primary structures of the 23S ribosomal RNA genes of Bacillin anthracis and an emetic strain of Bacillus cereus were determined by direct sequencing of enzymatically amplified chromosomal DNA and the feasibility of using PCR-direct sequencing for the rapid sequence determination of large-subunit rRNA genes is demonstrated.
Abstract: The primary structures of the 23S ribosomal RNA genes of Bacillus anthracis and an emetic strain of Bacillus cereus were determined by direct sequencing of enzymatically amplified chromosomal DNA. The 23S rRNA gene sequences of B. anthracis and B. cereus were found to be almost identical and showed only two differences (a single nucleotide change, and a single base insertion in B. cereus). The feasibility of using PCR-direct sequencing for the rapid sequence determination of large-subunit rRNA genes is demonstrated.
TL;DR: Some of the factors that are important in the large scale production by fermentation of poly- β-hydroxybutyrate: poly-β-Hydroxyvalerate (PHB/HV) copolymers are discussed.
Abstract: In this paper I shall discuss some of the factors that are important in the large scale production by fermentation of poly-β-hydroxybutyrate: poly-β-hydroxyvalerate (PHB/HV) copolymers. Many of the points discussed are common process features in any scale up procedure.
TL;DR: Based on comparative sequence analyses these organisms represent a hitherto unknown line of descent within the lactic acid group of bacteria for which a new genus, Atopobium gen. nov., is proposed.
Abstract: 16S rRNA gene sequencing was performed on the species Lactobacillus minutus, Lactobacillus rimae and Streptococcus parvulus in order to clarify their taxonomic position. Based on comparative sequence analyses these organisms represent a hitherto unknown line of descent within the lactic acid group of bacteria for which a new genus, Atopobium gen. nov., is proposed.
TL;DR: An Aspergillus fumigatus extracellular alkaline protease (ALP) which is an enzyme of the subtilisin family is a potential virulent factor of the fungus and the nucleotide sequence of this gene was compared to that of a cDNA encoding A. oryzae ALP.
Abstract: An Aspergillus fumigatus extracellular alkaline protease (ALP) which is an enzyme of the subtilisin family is a potential virulent factor of the fungus. The gene encoding ALP was isolated from a genomic library made from DNA of an A. fumigatus isolate. The nucleotide sequence of this gene was compared to that of a cDNA encoding A. oryzae ALP and to that of a cDNA from A. fumigatus encoding the mature ALP protein. Mature A. fumigatus ALP contains 282 amino acids and is encoded by three exons. The pre-proenzyme has a leader sequence of 121 amino acids.
TL;DR: A mutant of one of these strains was isolated which had lost azo-dye decolorizing ability and the strain was used to clone DNA conferring this ability, by screening a BclI library constructed from DNA of a decolorized strain.
Abstract: Azo dye are recalcitrant pollutants. Two sulfonated azo dyes, Orange II and Amino black, are effectively decolorized by certain noncardioform strains of the genus Rodococcus. A mutant of one of these strains was isolated which had lost azo-dye decolorizing ability and the strain was used to clone DNA conferring this ability, by screening of Bc/I library constructed from DNA of a decolorizing strain. The relevant genetic information was located on a 6.3-kb fragment of DNA.
TL;DR: Inhibition has only been observed of spore germination, of cell separation in budding yeasts and of the action of a yeast toxin, and not of apical extension or branching, but the finding that chitinase activities in situ have different properties to those in cell homogenates, and appear to be protected from environmental stresses is explained.
Abstract: Filamentous fungi with chitin as a major component of their cell walls produce chitinases at all stages of active growth, i.e. during spore germination, exponential growth and mycelial development. The roles of chitinases in these processes have been investigated by assessing the effects of treatment with the inhibitor, allosamidin. Inhibition has only been observed, however, of spore germination, of cell separation in budding yeasts and of the action of a yeast toxin, and not of apical extension or branching. This may be explained by the finding that chitinase activities in situ have different properties to those in cell homogenates, and appear to be protected from environmental stresses.
TL;DR: Phenotypic and genetic studies were performed on some atypical aeromonas strains of uncertain taxonomic position and revealed that these strains represent a hitherto unknown genetic line within the genus Aeromonas, for which the name AeromonAs allosaccharophila sp.
Abstract: Phenotypic and genetic studies were performed on some atypical aeromonad strains of uncertain taxonomic position. 16S rRNA gene sequence analysis revealed that these strains represent a hitherto unknown genetic line within the genus Aeromonas, for which the name Aeromonas allosaccharophila sp. nov. is proposed. The type strain is CECT 4199.
TL;DR: The non-culturable state of Vibrio vulnificus, strain C7184, was studied in artificial seawater microcosms held at 5, 10, 15, 20, and 30°C as mentioned in this paper.
Abstract: The non-culturable state of Vibrio vulnificus, strain C7184, was studied in artificial seawater microcosms held at 5, 10, 15, 20, and 30°C. Plate counts were made on a non-selective medium, total cell counts were monitored by acridine orange epifluorescence, and direct viable counts (DVSs) by the method of Kogure et al. (Can J. Microbiol. 25, 415–420; 1986) and by the INT method. From an initial inoculum of 107 cells/ml, V. vulnificus became non-culturable within 40 days at 5°C, although both indicators of viability revealed a viable population exceeding 106 cells/ml. Cells at all higher temperatures remained culturable (at least 104/ml) throughout the study. The non-culturable states of the opaque and translucent colony variants of V. vulnificus, as well as those of six other clinical and environmental strains of V. vulnificus, were examined at 5°C; all but one strain and both colony variants also became non-culturable within 40 days. In contrast, six other Vibrio spp. (V. cholerae, V. mimicus, V. parahaemolyticus, V. natriegens, V. proteolyticus, and V. campbelli) remained culturable at 5°C. Thus, entrance of V. vulnificus into the non-culturable state appears to be highly temperature dependent and, among the vibrios, this species may be especially sensitive to low temperature. The public health aspects of these findings are discussed.