Showing papers in "Journal of Applied Microbiology in 1981"
TL;DR: The results indicated that L. monocytogenes is present in sewage and sewage sludge in considerable numbers and that this organism survives longer than Salmonella spp.
Abstract: Listeria monocytogenes in sewage, sewage sludge and river water was isolated by enrichment at 4°C with subculture and enrichment in thiocyanate, naladixic acid broth and plating on to Tryptose Agar. The results indicated that L. monocytogenes is present in sewage and sewage sludge in considerable numbers and that this organism survives longer than Salmonella spp. on land sprayed with sewage sludge.
295 citations
TL;DR: Results of the study indicate that large numbers of toxigenic A. hydrophila can be found in an estuary and such strains may be pathogenic for man and/or animals.
Abstract: A microbiological survey of Aeromonas hydrophila in Chesapeake Bay and its tributaries showed that this species is ubiquitous, occurring in numbers ranging from <0.3/l to 5 × 103/ml in the water column and ca. 4.6 × 102/g in sediment. It was recovered from water samples collected at several locations in Chesapeake Bay representing various salinity regimes, but the numbers of A. hydrophila in higher salinity water, i.e. 15O/OO, were low. Results of stepwise multiple linear regression analysis showed that concentrations of A. hydrophila were correlated with total, aerobic, viable, heterotrophic, bacterial counts, and, in addition, were inversely related to salinity and to concentration of dissolved oxygen. Seasonal occurrence was recorded, with fewer strains of A. hydrophila encountered during the winter months. The potential pathogenicity of A. hydrophila strains isolated from Chesapeake Bay was estimated by testing selected isolates for toxigenicity, using the Y-1 adrenal cell assay. Of 116 isolates tested, 83 (71%) produced a cytotoxic response, a characteristic found to be correlated with the lysine decarboxylase and Voges-Proskauer reactions. Eight of 11 strains tested, which elicited fluid accumulation in the rabbit ligated ileal loop assay, also provoked a cytotoxic reaction in the Y-l adrenal cell assay. Results of the study indicate that large numbers of toxigenic A. hydrophila can be found in an estuary and such strains may be pathogenic for man and/or animals.
237 citations
TL;DR: It is concluded that group F is a synonym of group EF6 and that the strains within these groups should be classified in a new species named Vibrio fluvialis.
Abstract: A numerical taxonomic study has been carried out to establish the relationship of group F to other biochemically similar organisms within the family Vibrionaceae. A total of 154 strains were examined including 59 of group F. Out of 114 characters determined for each strain 100 were used to compute average Euclidean distances between strains. Four methods of clustering were used, all of which gave very similar results.
Strains resembling Vibrio anguillarum fell into clusters corresponding to V. anguillarum, Beneckea nereida and a previously unrecognized group, phenon 5. Strains of the Aeromonas hydrophila/punctata group formed a heterogenous phenon within which certain subdivisions, perhaps artificial, could be discerned.
Group F strains all fell in one closely-knit cluster distinct from all the species of Vibrio, Aeromonas, Plesiomonas and Photobacteriwn studied. Group F strains could be divided into two biovars, I and II. Both biovars are present in aquatic, particularly estuarine, environments throughout the world but biovar I strains have also been isolated from humans with diarrhoea. It is concluded that group F is a synonym of group EF6 and that the strains within these groups should be classified in a new species named Vibrio fluvialis. The type strain is NCTC 11327.
181 citations
TL;DR: Natural mixtures of bacterial ubiquinones (coenzyme Q) were separated according to the length of the polyisoprenyl side-chain using reverse-phase thin-layer chromatography and high performance liquid chromatography to afford a rapid and sensitive means of ubiquinone characterization.
Abstract: Natural mixtures of bacterial ubiquinones (coenzyme Q) were separated according to the length of the polyisoprenyl side-chain using reverse-phase thin-layer chromatography and high performance liquid chromatography. The chromatographic systems described afford a rapid and sensitive means of ubiquinone characterization.
157 citations
TL;DR: The resistance of proteases and lipases to inactivation by a treatment of 55°C for 1 h varied between and within species, therefore, this treatment may not have a widespread practical application.
Abstract: Proteases and lipases from a number of different species of psychrotrophic bacteria isolated from dairy products are resistant to heat treatments of 77°C for a holding time of 17 s and 140°C for a holding time of 5s A further treatment combining the 77°C for 17 s heating process with a heat treatment involving a temperature of 55°C for 1 h was also examined The proteases and, to a lesser extent, the lipases were also resistant to the treatments in combination The resistance of proteases and lipases to inactivation by a treatment of 55°C for 1 h varied between and within species Therefore, this treatment may not have a widespread practical application
149 citations
TL;DR: With one exception (NCIB 9668), the extracellular amylases from 10 strains of Bacillus licheniformis were thermostable and retained more than 98% of their original activity after incubation at 85°C for 60 min, and it was concluded that B. lichensiformis provides a good source of these enzymes.
Abstract: With one exception (NCIB 9668), the extracellular amylases from 10 strains of Bacillus licheniformis were thermostable and retained more than 98% of their original activity after incubation at 85°C for 60 min. The enzyme from B. licheniformis NCIB 6346 was purified 30-fold by ion-exchange chromatography and was characterized. It had an endo-action on starch yielding maltopentaose as the major product, and was identified as an α-amylase. The purified enzyme had a molecular weight of 62 650, was stable between pH 7 and 10 and was maximally active at 70-90°C at pH 7.0. It closely resembled commercial thermostable α-amylases in its general properties and it is concluded that B. licheniformis provides a good source of these enzymes.
139 citations
137 citations
TL;DR: Effects upon counting procedures, changes in levels through processes, detection of low levels of micro-organisms, the use of indicator groups, presence/absence tests, consumer safety calculations, and sample unit size analysed are explained.
Abstract: The distribution of micro-organisms within batches of food is identified as log-normal and this distribution has practical implications in the control of microbial hazards in foods. These implications are explained as effects upon counting procedures, changes in levels through processes, detection of low levels of micro-organisms, the use of indicator groups, presence/absence tests, consumer safety calculations, and sample unit size analysed.
127 citations
TL;DR: Slight differences in plasmid profiles, lysogenic status, prophage curability and temperate phage morphology were detected and it is suggested that these have evolved as a result of maintenance in different environments.
Abstract: Plasmid DNA from lactic streptococci was subjected to electrophoresis on agarose gels The plasmid profiles so obtained were strain specific and sufficiently stable to suggest their use in strain differentiation A group of Streptococcus lactis strains, 712 763 (ML3), 505 (C2) and 2031 (C2), found to have similar plasmid profiles, were shown to be closely related Gene transfer by transduction and conjugation occurred between members of this group at frequencies comparable to those in homologous systems and temperate phages cross plated readily between their prophage cured derivatives
Minor variations were, however, found between these four strains; slight differences in plasmid profiles, lysogenic status, prophage curability and temperate phage morphology were detected and it is suggested that these have evolved as a result of maintenance in different environments
108 citations
TL;DR: In order to devise a scheme for the identification and differentiation of agrobacteria, 50 strains of Agrobacterium, mostly those maintained in the National Collection of Plant Pathogenic Bacteria, were separated into four clusters when subjected to numerical taxonomic analysis.
Abstract: In order to devise a scheme for the identification and differentiation of agrobacteria, 50 strains of Agrobacterium, mostly those maintained in the National Collection of Plant Pathogenic Bacteria, were separated into four clusters when subjected to numerical taxonomic analysis. For the two major clusters, regardless of the phytopathogenic effect of the strains, we would adopt the species names A. tumefaciens and A. rhizogenes. A third cluster merits the use of the specific name A. rubi whilst a hitherto unrecognized fourth cluster of yellow-pigmented isolates may constitute a fourth species in the genus. The species name A. radiobacter is rejected as this species is synonymous with A. tumefaciens and the latter, being the type species of the genus, takes priority. To indicate the phytopathogenic effect of strains within our four Agrobacterium clusters we would use the terms: saprophytic state, tumourigenic state and rhizogenic state. Revised descriptions, without regard to phytopathogenic effect, are given for A. tumefaciens, A. rhizogenes and A. rubi.
104 citations
TL;DR: A study of the development of methanogenic fixed films on pieces of polyvinyl chloride plastic, etched glass and baked clay showed that support material markedly affected the rate of attachment and growth of bacteria converting acetic acid to methane as mentioned in this paper.
Abstract: A study of the development of methanogenic fixed films on pieces of polyvinyl chloride plastic, etched glass and baked clay showed that support material markedly affected the rate of attachment and growth of bacteria converting acetic acid to methane Film development, as indicated by the rate of acetate conversion to methane and carbon dioxide, was threefold faster on fired clay than on either PVC plastic or etched glass Scanning electron micrographs showed that the film of bacteria attached to clay was thick and uniform, while the film attached to PVC plastic was thin although still uniform Attachment to etched glass was spotty The characteristics of clay which made it a superior support appeared to be its rough, porous surface which offered attachment sites to the micro-organisms and the presence of minerals in the clay, particularly iron which is known to stimulate methanogenesis and growth
TL;DR: Addition of rifampicin (5µg/ml) to a number of media allowed the selective isolation of Actinomadura strains from soil and enabled large numbers of ‘Thermomonospora (Thm.) chromogena’ and Streptomyces albus to be isolated from hay and straw.
Abstract: Addition of rifampicin (5µg/ml) to a number of media allowed the selective isolation of Actinomadura strains from soil and enabled large numbers of ‘Thermomonospora (Thm.) chromogena’ and Streptomyces (St.) albus to be isolated from hay and straw. Saccharomonospora (S.) viridis was also tolerant to the antibiotic but was often inhibited by other isolates, while other bacteria including Micropolyspora faeni, ‘Thm. fusca’, Thermoactinomyces (Tha.) vulgaris and some other Streptomyces spp. were mostly sensitive, even to 2·5 µg/ml. Heating soil samples at 100°C for 15 min further decreased the number of unwanted bacteria growing on glucose-yeast extract agar supplemented with 5 µg/ml of rifampicin.
TL;DR: It was concluded that high partial pressures of CO2 have a considerable shelf-life prolonging effect by selecting the microflora towards Lactobacillus spp.
Abstract: Changes in the microbial flora of pork stored at 4 or 14°C were studied in 5 atm CO2, 1 atm CO2 or 1 atm air. The time needed for the total aerobic count at 4°C to reach 5 × 106 organisms/cm2 was about three times longer in 5 atm CO2 than in 1 atm CO2, and about 15 times longer in 5 atm CO2 than in air. At 14°C there was no difference in growth rate between 5 atm CO2 and 1 atm CO2. No off-odour was detected after storage in 5 atm CO2 for 14 d, but the pork in 1 atm CO2 (6 d) was organoleptically unacceptable.
The predominant organisms on the pork from the processing line were: Flavobacterium spp., Acinetobacter calcoaceticus, Pseudomonas spp., Micrococcus spp. and Moraxella spp. After aerobic storage at 4°C (8 d) or 14°C (3 d) more than 90% of the flora consisted of Pseudomonas spp. At 4°C all Pseudomonas spp. were of the non-fluorescent type, whilst at 14°C 32% were Ps. putida and Ps. fluorescens. After storage in 1 atm CO2Lactobacillus spp. represented 66% of the flora at 14°C (6 d) and 100% at 4°C (40 d), with L. xylosus dominating. After storage in 5 atm CO2Lactobacillus spp. constituted the total flora at both temperatures with L. lactis (14°C) and L. xylosus (4°C) dominating.
It was concluded that high partial pressures of CO2 have a considerable shelf-life prolonging effect by (i) selecting the microflora towards Lactobacillus spp. and (ii) reducing the growth rate of these Lactobacillus spp. The controlling and growth inhibitory effect of CO2 was promoted by reduced temperatures.
TL;DR: The effects of complete human intestinal flora and of intestinal anaerobes on germ-free mice were studied and the complete flora reduced caecal weight to normal values and induced an antagonistic effect against Escherichia coli.
Abstract: The effects of complete human intestinal flora and of intestinal anaerobes on germ-free mice were studied. The gross composition of the flora of mice was similar to that of the flora with which the animals had been contaminated and appeared to be stable provided that the animals were kept isolated. The complete flora and the anaerobes reduced caecal weight to normal values and induced an antagonistic effect against Escherichia coli. In contrast to the complete flora, the anaerobes were not invasive in immunosuppressed mice and induced colonization resistance and antagonism against Pseudomonas aeruginosa.
TL;DR: The antibiotic monensin was added to pure cultures of Bacteroides ruminicola, Selenomonas ruminantium, Anaerovibrio lipolytica and Megasphaera elsdenii to stop the digestion of chopped straw and dewaxed cotton fibres by rumen contents incubated in vitro.
Abstract: The antibiotic monensin was added to pure cultures of Bacteroides ruminicola, Selenomonas ruminantium, Anaerovibrio lipolytica and Megasphaera elsdenii. These organisms, representing succinate- and propionate-producing rumen bacteria, were not affected by monensin up to 10 μg/ml. Methanobacterium ruminantium was slightly inhibited by monensin, Butyrivibrio fibrisolvens, Ruminococcus albus and Streptococcus bovis were inhibited to differing extents by monensin at concentrations between 0.1 and 10 μg/ml. Bacteroides succinogenes was inhibited at first by monensin at >0.5 μg/ml but after a prolonged lag phase adapted to grow in the presence of monensin at concentrations below 5 μg/ml.
Monensin (1 μg/ml) almost completely stopped the digestion of chopped straw and dewaxed cotton fibres by rumen contents incubated in vitro. The digestion of grass and powdered filter paper was not significantly reduced under these conditions, but when the concentration of monensin was increased to between 3 and 5 μg/ml, the digestion of these substrates was reduced.
TL;DR: Twenty-four strains of pectolytic, fluorescent pseudomonads were isolated from soft rots of celery stored at 0.4-1°C and five strains were isolated in cabbage stored at 1°C, causing soft rot of wounded, but not of unwounded tissue.
Abstract: Twenty-four strains of pectolytic, fluorescent pseudomonads were isolated from soft rots of celery stored at 0.4-1°C and five strains were isolated from soft rots in cabbage stored at 1°C. When inoculated into the vegetable from which they were isolated these bacteria caused soft rot of wounded, but not of unwounded tissue. According to their biochemical reactions, the organisms were divided into three groups; Group 1 (15 strains) were identified with Pseudomonas fluorescens Biotype II (Doudoroff & Palleroni 1974) (Ps. marginalis); Group 2 (12 strains) and Group 3 (two strains) would be included in the ‘Miscellaneous strains’of Ps. fluorescens described by the above authors. One strain biochemically representative of Group 1 showed a maximum growth rate at 27°C (doubling time, 0.88 h) and a doubling time at 0.2°C of 14.9 h. A strain representative of Group 2 showed a maximum growth rate at 29°C (doubling time 0.96 h) and a doubling time at 0.2°C of 16.6 h. Neither strain grew at 36°C. The temperature characteristics (calculated for the range 0.2-20.8°C) were 83 011 and 79 534 J/mol, respectively. The mean doubling time for the remaining Group 1 strains at 0.2°C was 17.6 h and for remaining Group 2 strains was 17.1 h.
TL;DR: Biochemical, immunological and morphological properties of mouse virulent Staphylococcus epidermidis strains ATCC-31432, SE-360 and SE-10 isolated from clinical specimens were compared and it was found that hyperimmune rabbit serum prepared with these strains passively protected mice against challenge infection only with the homologous strain.
Abstract: Biochemical, immunological and morphological properties of mouse virulent Staphylococcus epidermidis strains ATCC-31432, SE-360 and SE-10 isolated from clinical specimens were compared. Heat-killed organisms and cell surface polysaccharides extracted from cell surface fractions induced resistance in mice only against challenge with the homologous strain. Hyperimmune rabbit serum prepared with these strains passively protected mice against challenge infection only with the homologous strain. Protective activity in immune sera was absorbed by homologous whole cell and cell surface polysaccharide, but not by heterologous organisms and cell surface polysaccharide. In agar diffusion tests, cell surface polysaccharides from strains ATCC-31432, SE-360 and SE-10 produced single precipitin lines only with the homologous antiserum. The outermost layer of ultra-thin sections of the three strains was labelled by homologous but not by heterologous ferritin-conjugated serum. Biochemical analysis of the cell surface polysaccharides showed that they were composed of hexosamine, glycerol, phosphorous, alanine, glycine and phenylalanine. The three strains ATCC-31432, SE-360 and SE-10 were regarded as different from each other. Thirteen of 300 fresh isolates of Staph. epidermidis randomly selected from human clinical specimens proved to be virulent for mice. With ATCC-31432, SE-360 and SE-10 tentatively designated as capsular-type I, type II and III, respectively, a majority of mouse virulent strains belonged to capsular-type II.
TL;DR: Menaquinones were the sole isoprenoid quinones found in 28 of the 34 halophilic organisms examined, whereas ubiquinones with nine isoprene units predominated in Flavobacterium halmephilum, Paracoccus halodenitrificans and Pseudomonas beijerinkii.
Abstract: Menaquinones were the sole isoprenoid quinones found in 28 of the 34 halophilic organisms examined. Unsaturated and dihydrogenated menaquinones with eight isoprene units were found in some alkalophilic halophiles and representatives of the genera Halobacterium and Halococcus. Brevibacterium halotolerans and Micrococcus halobius possessed major amounts of unsaturated menaquinones with seven and eight isoprene units, respectively. Actinopolyspora halophila possessed complex mixtures of partially hydrogenated menaquinones with tetrahydrogenated menaquinones with nine isoprene units predominating. Vibrio costicola possessed both menaquinones and ubiquinones with eight isoprene units. Ectothiorhodospira halophila, Flavobacterium halmephilum, Paracoccus halodenitrificans and Pseudomonas beijerinkii contained ubiquinones as their sole respiratory quinones. Ectothiorhodospira halophila possessed major amounts of ubiquinones with eight isoprene units whereas ubiquinones with nine isoprene units predominated in Flavobacterium halmephilum, Paracoccus halodenitrificans and Pseudomonas beijerinkii.
TL;DR: A differential medium has been developed for the simultaneous enumeration of Lactobacillus bulgaricus and Streptococcus thermophilus from yoghurt.
Abstract: A differential medium has been developed for the simultaneous enumeration of Lactobacillus bulgaricus and Streptococcus thermophilus from yoghurt. After incubating in a ‘candle jar’ at 42°C, a first count can usually be made at 24 h.
TL;DR: In this article, a rapid direct epifluorescent filter technique (DEFT) was used to enumerate bacteria in heat-treated milk and milk-products, and the DEFT count could detect as few as 5750 bacteria in pasteurized and skim milk, pasteurized cream, whey and sweet cream butter.
Abstract: A rapid direct epifluorescent filter technique (DEFT), taking ca. 20 min to complete, was used to enumerate bacteria in heat-treated milk and milk-products. The DEFT count could detect as few as 5750 bacteria/ml in pasteurized and skim milk, pasteurized cream, whey and sweet cream butter and was in agreement with the standard plate count. The technique was also used to determine the sterility of cartoned ultra heat-treated milk after incubation at 37°C. The agreement between the DEFT and plate count was poor for evaporated and condensed milks, some reconstituted skim milk powders, pasteurized whey and ripened cream butter. Possible reasons for this are discussed.
TL;DR: Evidently, the Flavobacterium hydrolase differs from that of Pseudomonas sp.
Abstract: Flavobacterium sp. ATCC 27551 hydrolysed both diethyl (parathion and diazinon) and dimethyl (methyl parathion and fenitrothion) phosphorothioates while Pseudomonas sp. ATCC 29353 hydrolysed only diethyl (parathion and diazinon) phosphorothioates. Glucose inhibited the hydrolysis of parathion by Pseudomonas sp., but not by Flavobacterium sp. Evidently, the Flavobacterium hydrolase differs from that of Pseudomonas sp. The Pseudomonas sp. converted 4-nitrophenol to 4-aminophenol in the presence of glucose and to nitrite in its absence; 4-nitrophenol was not metabolized by the Flavobacterium sp.
TL;DR: Factory trials where the scald water was maintained at pH 9.0 ± 0.2 for the after-lunch period showed that both the total bacterial population and the number of coli-aerogenes organisms were substantially reduced and sodium carbonate was as effective as NaOH in increasing the death rate of Salm.
Abstract: In laboratory experiments adjustment of the pH of chicken scald-tank water to 9.0 ± 0.2 lowered the D52°C value of a strain of Salmonella typhimurium from 34.5 to 1.25 min. Factory trials where the scald water was maintained at pH 9.0 ± 0.2 for the after-lunch period showed that both the total bacterial population and the number of coli-aerogenes organisms were substantially reduced. Addition of sodium hydroxide also increased the rate of accumulation of total dry matter in the water. Sodium carbonate was as effective as NaOH in increasing the death rate of Salm. typhimurium and would appear to be a suitable alternative.
TL;DR: Monitoring of calves intensively reared on a milk replacer diet for salmonella and Escherichia coli excretion patterns suggested that transfer from the salmonellas to Esch.
Abstract: A batch of 40 calves intensively reared on a milk replacer diet was monitored over 34 d for salmonella and Escherichia coli excretion patterns. A total of 1055 Esch. coli was isolated on unsupplemented bile lactose agar (BLA), and 537 on BLA supplemented with chloramphenicol, from 10 selected calves. The antibiotic resistance pattern and O-serogroup were determined for each isolate.
Salmonella typhimurium phage type DT 193 carrying six R determinants was detected in five calves on intake; after 14 d 28 were excreting the organism but by the time the calves left the farm (34 d) only a small number were found to be excreting the organism indicating that the infection was self limiting by about six weeks of age. In contrast, multiply resistant Esch. coli were being excreted in increasing numbers with time. Of the isolates on BLA 95.5% were resistant to at least one antibacterial agent and many were resistant to up to six agents. An unusually high proportion (49%) was resistant to chloramphenicol and this R determinant was frequently associated with R determinants for at least streptomycin, sulphonamide and tetracycline, a combination regularly present in the salmonellas. Chloramphenicol resistance is carried on an H2 plasmid in Salmonella typhimurium phage type 193 and it was found that 11% of 146 randomly selected isolates of Esch. coli, carrying the same range of R determinants, were infected with an H2 plasmid. H2 plasmids were found in a number of O-sero-groups of Esch. coli and chloramphenicol resistance was present in 37 O-serogroups. It is suggested that transfer from the salmonellas to Esch. coli possibly took place before the calves entered the farm and the transconjugants were selected by the antibiotics used on the farm. Subsequent transfer between Esch. coli could explain the wide distribution of chloramphenicol-resistance in many serogroups. The transfer of H2 plasmids is thermosensitive and no transfer could be demonstrated in vivo but occurred readily in voided faeces held at 28°C. The importance of Esch. coli as a reservoir of chloramphenicol resistance and the public health implications are discussed.
TL;DR: Combined analysis of three experiments showed that when lamb carcases with initial bacterial numbers of between logi103 and 4.22/cm2 were spray washed, statistically significant reductions inacterial numbers of log10O were obtained, and at highly contaminated sites increasing the duration of spraying from 30 to 120 s significantly increased the reductions obtained when water containing added chlorine was used.
Abstract: Combined analysis of three experiments showed that when lamb carcases with initial bacterial numbers of between logi103.29 and 4.22/cm2 were spray washed, statistically significant reductions in bacterial numbers of log10O.5 were obtained when the spray wash water temperature was > 57°C, and reductions of log101.0 were obtained when the temperature was ≥ 80°C. Reductions at all temperatures were enhanced by log100.66 when the water contained 30 µg/ml chlorine, but increasing the concentration to 450 µg/ml reduced bacterial numbers only by a further log100–29. At highly contaminated sites increasing the duration of spraying from 30 to 120 s significantly increased the reductions obtained when water containing added chlorine was used. Reductions in bacterial numbers after spray washing with pressures of 3.5, 5.6. 7.7 kg/cm2 were not significantly different.
TL;DR: Advantage was taken of this selective effect and of the synergistic action of polymyxins and sulphonamides on Proteus strains to improve the selective capacity of Baird-Parker's Staph.
Abstract: Acriflavine was found to be less inhibitory to Staphylococcus aureus than to other staphylococci. Advantage was taken of this selective effect and of the synergistic action of polymyxins and sulphonamides on Proteus strains to improve the selective capacity of Baird-Parker's Staph. aureus isolation medium. A supplement mixture containing acriflavine, sodium sulphamezathine and low levels of polymyxin in addition to the usual egg yolk and potassium tellurite is proposed for use with this medium.
TL;DR: The minimal inhibitory concentrations of 11 growth promoting agents were determined by agar-dilution method against 113 strains of lactobacilli isolated from caeca of pigs, cattle and poultry.
Abstract: The minimal inhibitory concentrations of 11 growth promoting agents were determined by agar-dilution method against 113 strains of lactobacilli isolated from caeca of pigs, cattle and poultry. Only Lactobacillus acidophilus strains were susceptible to avoparcin and all strains were resistant to copper sulphate. Resistance was noted in cattle and poultry strains against bacitracin, in pig strains against virginiamycin, and in pig and poultry strains against nitrovin. Resistance against carbadox, flavomycin, lincomycin, oleandomycin, spiramycin and tylosin was noted in strains from all three host species.
TL;DR: No peculiar physiological property such as nitrogen-scavenging, ability to survive at the expense of intracellular PHB or protein, abnormally low cellular protein content, low maintenance energy requirements or a low adenylate charge state fully account for the starvation resistance of these marine bacteria.
Abstract: The survival under starvation conditions of two selected strains of marine bacteria, a yellow Pseudomonas sp. (strain 95A) and an unidentified oxidative peritrichate Gram negative rod (strain 41), was investigated. The 50% survival times of suspensions in phosphate buffer depended on cell density and were often more than 20 d. A capacity to scavenge atmospheric nitrogenous compounds led to a marked increase in the viability of cell suspensions of 104 cells/ml. Intracellular poly-β-hydroxybutyrate (PHB) prolonged the survival of strain 95A. Strain 41 contained more intracellular protein and this was degraded during starvation in ammonia-free air. Prolonged survival was not explicable in terms of low adenylate charge states. The ‘maintenance energy’requirements of strains 95A and 41 in chemostat cultures were 0.042 and 0.04 g glucose/g dry wt/h respectively, compared with dilution-rate-dependent values of 0.051 to 0.856 for Escherichia coli. The low maintenance energy requirements would not alone explain the long viability. Thus no peculiar physiological property such as nitrogen-scavenging, ability to survive at the expense of intracellular PHB or protein, abnormally low cellular protein content, low maintenance energy requirements or a low adenylate charge state fully account for the starvation resistance of these marine bacteria.
TL;DR: Pseudomonas-like bacteria isolated from fresh and spoiling fish in southeastern Queensland were subjected to a wide range of physiological and nutritional tests, together with those of 20 named strains, which were analysed numerically, resulting in the formation of 11 groups.
Abstract: Pseudomonas-like bacteria isolated from fresh and spoiling fish in southeastern Queensland were subjected to a wide range of physiological and nutritional tests. The results of these tests, together with those of 20 named strains, were analysed numerically, resulting in the formation of 11 groups. Most of the isolates clustered into group 1 and group 2 which also contained the bulk of the strains able to produce spoilage odours when grown in a tryptic digest of fish muscle at 2°C. Almost all of the group 1 organisms produced sulphydryl type odours, had only 50 mol % G + C and were identified as strains of Alteromonas putrefaciens which were deficient in the ability to produce H2S detectable in Peptone Iron Agar. Certain of the group 2 strains produced fruity and sulphydryl type odours, but these organisms were not distinguishable from other strains in this group not producing odours. Group 2 strains were highly related to Pseudomonas fragi and were intermediate in properties between Ps. fluorescens and Ps. putida. The remaining nine minor groups contained few organisms able to produce spoilage odours.