Showing papers on "Bacteria published in 1983"
TL;DR: In this article, two newly isolated filamentous sulfate-reducing bacteria, Desulfonema limicola and 4be13, were investigated for motility, ultrastructure and nutrition.
Abstract: Gliding motility, ultrastructure and nutrition of two newly isolated filamentous sulfate-reducing bacteria, strains 5ac10 and 4be13, were investigated. The filaments were always attached to surfaces. Growth was supported by addition of insoluble aluminium phosphate or agar as substrata for gliding movement. Electron microscopy of ultrathin sections revealed cell walls characteristic of Gramnegative bacteria; the undulated structure of the outer membrane may pertain to the translocation mechanism. Intracytoplasmic membranes were present. Acetate, higher fatty acids, succinate or fumarate served as electron donors and carbon sources. Strain 5ac10 grew also with lactate, but not with benzoate that was used only by strain 4be13. Strain 5ac10 was able to grow slowly on H2 plus CO2 or formate in the presence of sulfate without additional organic carbon source. The capacity of complete oxidation was shown by stoichiometric measurements with acetate plus sulfate. Both strains contained b- and c-type cytochromes. Desulfoviridin was detected only in strain 5ac10. The two filamentous gliding sulfate reducers are described as new species of a new genus, Desulfonema limicola and Desulfonema magnum.
910 citations
TL;DR: Limiting of growth must be regarded as the primary mechanism controlling bacterial populations in the large intestine because two or more bacterial strains that compete in the gut for the same limiting nutrient can coexist, if the metabolically less efficient strains have specific adhesion sites available.
Abstract: Preliminary experiments established that a 0.5-ml inoculum that is introduced directly into the stomach of mice was cleared rapidly into the small intestine. Bicarbonate buffer, but not skim milk, protected such an inoculum from stomach acid until at least 90% of it had entered the small intestine. Passage and survival of various Escherichia coli strains through the mouse gut were tested by introducing a buffered bacterial inoculum directly into the stomach, together with the following two intestinal tracers: Cr(51)Cl(3) and spores of a thermophilic Bacillus sp. Quantitative recovery of excreted bacteria was accomplished by collecting the feces overnight in a refrigerated cage pan. The data show that wild-type E. coli strains and E. coli K-12 are excreted rapidly (98 to 100% within 18 h) in the feces without overall multiplication or death. E. coli varkappa1776 and DP50supF, i.e., strains certified for recombinant DNA experiments underwent rapid death in vivo, such that their excretion in the feces was reduced to approximately 1.1 and 4.7% of the inoculum, respectively. The acidity of the stomach had little bactericidal effect on the E. coli K-12 strain tested, but significantly reduced the survival of more acidsensitive bacteria (Vibrio cholerae) under these conditions. Long-term implantation of E. coli strains into continuous-flow cultures of mouse cecal flora or into conventional mice was difficult to accomplish. In contrast, when the E. coli strain was first inoculated into sterile continuous-flow cultures or into germfree mice, which were subsequently associated with conventional mouse cecal flora, the E. coli strains persisted in a large proportion of the animals at levels resembling E. coli populations in conventional mice. Metabolic adaptation contributed only partially to the success of an E. coli inoculum that was introduced first. A mathematical model is described which explains this phenomenon on the basis of competition for adhesion sites in which an advantage accrues to the bacterium which occupies those sites first. The mathematical model predicts that two or more bacterial strains that compete in the gut for the same limiting nutrient can coexist, if the metabolically less efficient strains have specific adhesion sites available. The specific rate constant of E. coli growth in monoassociated gnotobiotic mice was 2.0 h(-1), whereas the excretion rate in conventional animals was -0.23 h(-1). Consequently, limitation of growth must be regarded as the primary mechanism controlling bacterial populations in the large intestine. The beginnings of a general hypothesis of the ecology of the large intestine are proposed, in which the effects of the competitive metabolic interactions described earlier are modified by the effects of bacterial association with the intestinal wall.
277 citations
01 Jan 1983
TL;DR: Studies of the primary structures of CAT variants suggest a marked degree of heterogeneity but conservation of amino acid sequence at and near the putative active site, although one or more cysteine residues are protected from thiol reeagents by substrates.
Abstract: Naturally occurring chloramphenicol resistance in bacteria is normally due to the presence of the antibiotic inactivating enzyme chloramphenicol acetyltransferase (CAT) which catalyzes the acetyl-S-CoA-dependent acetylation of chloramphenicol at the 3-hydroxyl group. The product 3-acetoxy chloramphenicol does not bind to bacterial ribosomes and is not an inhibitor of peptidyltransferase. The synthesis of CAT is constitutive in E. coli and other Gram-negative bacteria which harbor plasmids bearing the structural gene for the enzyme, whereas Gram-positive bacteria such as staphylococci and streptococci synthesize CAT only in the presence of chloramphenicol and related compounds, especially those with the same stereochemistry of the parent compound and which lack antibiotic activity and a site of acetylation (3-deoxychloramphenicol). Studies of the primary structures of CAT variants suggest a marked degree of heterogeneity but conservation of amino acid sequence at and near the putative active site. All CAT variants are tetramers composed in each case of identical polypeptide subunits consisting of approximately 220 amino acids. The catalytic mechanism does not appear to involve an acyl-enzyme intermediate although one or more cysteine residues are protected from thiol reeagents by substrates. A highly reactive histidine residue has been implicated in the catalytic mechanism.
262 citations
TL;DR: Bacterial communities of different respiratory types were isolated from a marine sediment in a multiple chemostat system in an attempt to obtain bacterial cultures representative of the sediment to enable the various respiratory types to be recognized by their particular fatty acid composition.
Abstract: Bacterial communities of different respiratory types were isolated from a marine sediment in a multiple chemostat system in an attempt to obtain bacterial cultures representative of the sediment. The fatty acid distribution of a mixed culture of sulphate-reducing bacteria isolated from this system showed a good correlation with the lipid distribution of the zone of maximum sulphate-reduction activity within the sediment. Both distributions had significant concentrations of C14 : 0, iso and anteiso C15 : 0, C16 : 0, C16 : 1ω7 and C18 : 1ω7. This was in contrast to the lipid profile of Desulfovibrio desulfuricans obtained by batch enrichment, which was dominated by iso C17 : 1ω7 fatty acids and correlated poorly with the sediment. The bacterial community cultured from the sediment was further differentiated according to respiratory types (aerobic, facultative aerobic and facultative anaerobic) by growth in a chemostat under defined conditions. The fatty acid distributions of these communities were sufficiently different to enable the various respiratory types to be recognized by their particular fatty acid composition. Cyclopropyl fatty acids (▿17 and ▿19) were present in significant levels only in the aerobic bacteria, while the facultative aerobes had significantly higher C18 : 1ω7 than the other cultures and the facultative anaerobic community was the only culture to have significant amounts of C12 : 0. The fatty acid distribution of Loch Eil sediment over the range C12-19 seemed to be predominantly of bacterial origin and were relatively abundant to a depth of 6 cm. The concentration of cyclopropyl fatty acids was highest in the oxidized surface sediments and decreased with depth as anaerobic conditions began to dominate, indicating that these fatty acids may only be indicative of aerobic sedimentary bacteria. In contrast to the fatty acids characteristic of bacteria, those fatty acids in the range C20-30 attributed to a terrestrial input were found in relatively constant concentrations over the whole 0–12 cm depth profile.
261 citations
TL;DR: It is shown that it is possible to sensitizeasive Gram-negative enteric bacteria to both complement and antibiotics by using an agent that binds to the outer membrane, which is a nontoxic derivative of polymyxin which by itself has no bactericidal action.
Abstract: A major virulence factor of bacteria that cause generalized infections is their resistance to the lytic action of the complement cascade, an important defence mechanism of the host. Invasive Gram-negative enteric bacteria, which cause about one-third of all bacteraemic infections, are completely resistant to lysis by complement, even in the presence of hyperimmune serum. The same bacteria are also resistant to many antibiotics that are effective therapeutic agents against other bacteria, as the outermost surface layer (the outer membrane) of the bacteria functions as a permeability barrier. Here we show that it is possible to sensitize such bacteria to both complement and antibiotics by using an agent that binds to the outer membrane. This agent is a nontoxic derivative of polymyxin which by itself has no bactericidal action.
228 citations
TL;DR: A major role of the cellulose fibrils synthesized by A. tumefaciens appears to be anchoring the bacteria to the host cells, thereby aiding the production of tumors.
Abstract: During the attachment of Agrobacterium tumefaciens to carrot tissue culture cells, the bacteria synthesize cellulose fibrils. We examined the role of these cellulose fibrils in the attachment process by determining the properties of bacterial mutants unable to synthesize cellulose. Such cellulose-minus bacteria attached to the carrot cell surface, but, in contrast to the parent strain, with which larger clusters of bacteria were seen on the plant cell, cellulose-minus mutant bacteria were attached individually to the plant cell surface. The wild-type bacteria became surrounded by fibrils within 2 h after attachment. No fibrils were seen with the cellulose-minus mutants. Prolonged incubation of wild-type A. tumefaciens with carrot cells resulted in the formation of large aggregates of bacteria, bacterial fibrils, and carrot cells. No such aggregates were formed after the incubation of carrot cells with cellulose-minus A. tumefaciens. The absence of cellulose fibrils also caused an alteration in the kinetics of bacterial attachment to carrot cells. Cellulose synthesis was not required for bacterial virulence; the cellulose-minus mutants were all virulent. However, the ability of the parent bacterial strain to produce tumors was unaffected by washing the inoculation site with water, whereas the ability of the cellulose-minus mutants to form tumors was much reduced by washing the inoculation site with water. Thus, a major role of the cellulose fibrils synthesized by A. tumefaciens appears to be anchoring the bacteria to the host cells, thereby aiding the production of tumors.
224 citations
205 citations
TL;DR: The proteolytic systems of lactic acid bacteria are described in relation to their growth and their functions in protein-rich foods and their role in the manufacture of milk products is discussed.
Abstract: The proteolytic systems of lactic acid bacteria are important as a means of making protein and peptide N available for growth and as part of the curing or maturation processes which give foods their characteristic rheological and organoleptic properties. The proteolytic systems of lactic acid bacteria are described in relation to their growth and their functions in protein-rich foods. Their role in the manufacture of milk products is discussed.
199 citations
TL;DR: The susceptibility of Manduca sexta larvae to infection by several Gram-negative bacteria has been examined in this article, where the authors found that the concentrations of viable cells of all three bacteria were reduced significantly during the first hour following injection at all doses tested.
195 citations
TL;DR: Bacteria regulate the fluidity of their membrane phospholipids in response to temperature through the activity of a soluble enzyme, β-ketoacyl-acyl carrier protein synthase II, of the fatty acid biosynthetic pathway.
192 citations
TL;DR: Metronidazole and related 5-nitroimidazoles are relatively nontoxic, however, reduction of their nitro group leads to the production of short-lived cytotoxic intermediates, which finally decompose into nontoxic end products.
TL;DR: A simple method for measuring the missense substitution of amino acids at specified positions in proteins synthesized in vivo is developed and finds that the frequency of cysteine substitution for the single arginine in Escherichia coli ribosomal protein L7/L12 is close to 10(‐3) for wild‐type bacteria, decreases to 4 x 10 (‐4) in streptomycin‐resistant bacteria, and is virtually unchanged in Ram bacteria containing mutant S4.
Abstract: We have developed a simple method for measuring the missense substitution of amino acids at specified positions in proteins synthesized in vivo We find that the frequency of cysteine substitution for the single arginine in Escherichia coli ribosomal protein L7/L12 is close to 10(-3) for wild-type bacteria, decreases to 4 x 10(-4) in streptomycin-resistant bacteria containing mutant S12 (rpsL), and is virtually unchanged in Ram bacteria containing mutant S4 (rpsD) We have also found that the frequency of the cysteine substitution for the single tryptophan in E coli ribosomal protein S6 is 3-4 x 10(-3) for wild-type bacteria, decreases to 6 x 10(-4) in streptomycin-resistant bacteria and is elevated to nearly 10(-2) in Ram bacteria
TL;DR: When the growth of aerobic spoilage bacteria is inhibited, lactic acid bacteria may become the dominant component of the microbial flora of meats and this occurs with cured meats and with meats packaged in films of low gas permeability.
Abstract: When the growth of aerobic spoilage bacteria is inhibited, lactic acid bacteria may become the dominant component of the microbial flora of meats. This occurs with cured meats and with meats packaged in films of low gas permeability. The presence of a flora of psychrotrophic lactic acid bacteria on vacuum-packaged fresh chilled meats usually ensures that shelf-life is maximal. When these organisms spoil meats it is generally by causing souring, however other specific types of spoilage do occur. Some strains cause slime formation and greening of cured meats, and others may produce hydrogen sulphide during growth on vacuum-packaged beef. The safety and stability of fermented sausages depends upon fermentation caused by lactic acid bacteria. Overall the presence on meats of lactic acid bacteria is more desirable than that of the types of bacteria they have replaced.
TL;DR: Representative N2-fixing bacteria have been isolated from the rhizosphere of rice using the "sper atmosphere model" and the most commonly encountered isolates belong to the genus Azospirillum and to Pseudomonas paucimobilis, a taxon related to Flavobacterium capsulatum.
Abstract: Representative N2-fixing bacteria have been isolated from the rhizosphere of rice using the "spermosphere model." They have been characterized using conventional biochemical tests, DNA composition,...
TL;DR: The malolactic enzyme of Lactobacillus plantarum was purified from 5.5 units/mg to a specific activity of 265 units/ mg of protein, and this enzyme can be distinguished from the well known malic enzymes.
TL;DR: A simple method of isolating bacteria that utilize cyanide as a source of nitrogen for growth has been developed, with results showing that cyanide-grown bacteria produced stoichiometric amounts of ammonia from cyanide when pulsed with cyanide under aerobic conditions.
Abstract: SUMMARY: A simple method of isolating bacteria that utilize cyanide as a source of nitrogen for growth has been developed This involved supplying hydrogen cyanide as a vapour to glucose-containing minimal-salts agar plates The bacteria isolated were Gram-negative, oxidase-positive rods producing a fluorescent green pigment and were tentatively identified as strains of Pseudomonas fluorescens Three organisms were studied further and shown to be P fluorescens biotype II One of these (NCIB 11764) was grown in a glucose-containing fed-batch culture with either NH4Cl or KCN as the limiting nutrient Cyanide-grown bacteria produced stoichiometric amounts of ammonia from cyanide when pulsed with cyanide under aerobic conditions Stimulation of oxygen uptake was seen on addition of cyanide to suspensions of cyanide-grown but not ammonia-grown bacteria
TL;DR: Fibronectin binds non-covalently to Gram-positive and Gram-negative bacteria and to yeast but did not appear to be necessary or sufficient for uptake of Staphylococcus aureus and Salmonella typhimurium by several different phagocytic cell types.
Abstract: The involvement of plasma fibronectin in phagocytosis of bacteria was investigated by testing the binding of fibronectin to several species of bacteria and by evaluating the ability of fibronectin to promote binding and endocytosis of two species of these bacteria by phagocytic cells. Fibronectin binds non-covalently to Gram-positive and Gram-negative bacteria and to yeast but did not appear to be necessary or sufficient for uptake of Staphylococcus aureus and Salmonella typhimurium by several different phagocytic cell types.
TL;DR: The physiological background of this endosymbiosis and its functioning in degradation processes in the anoxic environment are discussed.
Abstract: Fluorescent bacteria were demonstrated to be abundantly spread as single cells throughout the cytoplasm of the giant amoeba Pelomyxa palustris, the sapropelic ciliate Metopus striatus and six other anaerobic protozoa examined. The endosymbionts of P. palustris and M. striatus were identified as methanogenic bacteria on the basis of the presence of the deazaflavin coenzyme F420 and the pterin compound F342. Moreover individuals of P. palustris produced methane over a long period of incubation. The number of methanogenic bacteria was above 1010 cells/ml protozoal cytoplasm. Two types of methanogenic bacteria together with unidentified thick bacteria were found in P. palustris. The physiological background of this endosymbiosis and its functioning in degradation processes in the anoxic environment are discussed.
TL;DR: Phytoplankton release of extracellular dissolved organic carbon and its subsequent assimilation by planktonic bacteria was quantified using the procaryotic inhibitor streptomycin, an active bactericidal agent, which affected algal photosynthesis in some cases.
Abstract: Phytoplankton release of extracellular dissolved organic carbon (EOC) and its subsequent assimilation by planktonic bacteria was quantified using the procaryotic inhibitor streptomycin. The carbon flow was assayed in the Danish estuary. Randers Fjord, and in laboratory experiments. From 34 to 90 % of the released carbon was transported to the bacteria; the bacterial metabolism of EOC ranged from 3 to 30 % of total primary production. If no correction for bacterial respiration (20 to 50 Oh) is made the EOC transport can be seriously underestimated. The released products were predominantly of low molecular weight (< 900 Daltons). The bacteria showed distinct selectivity for these small molecules. Streptomycin, an active bactericidal agent, also affected algal photosynthesis in some cases. In carbon flow experiments antibiotics must be used with great care.
Patent•
16 Sep 1983
TL;DR: Hyaluronic acid, a polysaccharide, is prepared in high yield from streptococcus bacteria by fermenting the bacteria under anaerobic conditions in a CO2-enriched growth medium, separating the bacteria from the resulting broth and isolating the hyaluronic acid from the remaining constituent of the broth.
Abstract: Hyaluronic acid, a polysaccharide, is prepared in high yield from streptococcus bacteria by fermenting the bacteria under anaerobic conditions in a CO2-enriched growth medium, separating the bacteria from the resulting broth and isolating the hyaluronic acid from the remaining constituent of the broth. The bacteria may be grown free of endotoxins by filtering all ingredients through a 10K Millipore (Reg. Trademark) filter prior to inoculation of the medium and subsequently maintaining pyrogen-free conditions. Separation of the microorganisms from the polysaccharide is facilitated by killing the bacteira with trichloroacetic acid. After removal of the bacterial cells and concentration of the higher molecular weight fermentation products, the hyaluronic acid is isolated and purified by precipitation, resuspension and reprecipitation.
TL;DR: Under anaerobic conditions, bacterial suspensions from rat intestinal contents converted 1-nitropyrene to one major and two minor metabolites, indicating that a wide range of intestinal bacteria are able to reduce this polycyclic nitroaromatic hydrocarbon.
Abstract: The microbial metabolism of the mutagenic and carcinogenic polycyclic nitroaromatic hydrocarbon, 1-nitropyrene, has been studied. Under anaerobic conditions, bacterial suspensions from rat intestinal contents converted 1-nitropyrene to one major and two minor metabolites. The rate of metabolism by rat intestinal microflora (10(9) bacteria/ml) was rapid with greater than 90% conversion occurring within 1 h. The major metabolite was identified as 1-aminopyrene through high pressure liquid chromatographic and mass spectral comparisons with an authentic standard. The suspected metabolites, N-acetyl-1-aminopyrene, 1-nitrosopyrene, N-hydroxy-1-aminopyrene, and 3-, 6-, and 8-hydroxy-1-nitropyrene were synthesized, but these derivatives were not detected in culture extracts from rat intestinal contents incubated anaerobically with 1-nitropyrene. Nine genera of anaerobic and facultative bacteria normally associated with the intestine also converted 1-nitropyrene to 1-aminopyrene. These data indicate that a wide range of intestinal bacteria are able to reduce 1-nitropyrene. The results are discussed in relation to the in vivo metabolism of this polycyclic nitroaromatic hydrocarbon.
TL;DR: From the culture supernatant of the myxobacterium, Myxococcus fulvus strain Mx f50, an antibiotic activity was isolated which blocked growth of many Gram-positive and several Gram-negative bacteria, but not of yeasts and fungi.
Abstract: From the culture supernatant of the myxobacterium, Myxococcus fulvus strain Mx f50, an antibiotic activity was isolated which blocked growth of many Gram-positive and several Gram-negative bacteria, but not of yeasts and fungi. The activity consisted of two closely related compounds, myxopyronins A and B. The myxopyronins appear to be new antibiotics, and seem to specifically inhibit bacterial RNA polymerase.
TL;DR: The data suggest that certain piliated strains of bacteria can enhance C. albicans attachment to epithelial cells and that type 1 pili ofacteria can be a factor in the enhanced attachment of C.Albicans to epithelium.
Abstract: The effects of carbohydrates (mannose and dextrose). Escherichia coli 07KL. and Klebsiella pneumoniae on Candida albicans attachment to epithelial cells was studied. Dextrose had no effect on yeast attachment to epithelial cells. Conversely, mannose significantly decreased both yeast and piliated bacterial attachment (E. coli 07KL, heavily piliated K. pneumoniae) whereas having no effect on nonpiliated K. pneumoniae attachment to epithelial cells. The number of yeasts attaching to epithelial cells was enhanced by preincubation of epithelial cells with piliated strains of bacteria, whereas preincubation with nonpiliated strains of bacteria had no effect on yeast attachment. Scanning electron microscopy showed that piliated bacteria and yeasts were juxtaposed on the epithelial cell surface. These data suggest that certain piliated strains of bacteria can enhance C. albicans attachment to epithelial cells and that type 1 pili of bacteria can be a factor in the enhanced attachment of C. albicans to epithelial cells.
TL;DR: Xylitol inhibited the growth of all but one of ten strains of S. mutans and failed to inhibit the grow of the lactobacilli, actinomycetes, and other streptococci tested except S. sanguis 10556, which was slightly inhibited.
Abstract: We investigated the effect of xylitol on the growth of different oral bacteria in the presence of glucose. Xylitol inhibited the growth of all but one of ten strains of S. mutans and failed to inhibit the growth of the lactobacilli, actinomycetes, and other streptococci tested except S. sanguis 10556, which was slightly inhibited. However, the rate of acid production of the sensitive S. mutans strains was not equally affected by xylitol. These data, obtained with pure cultures of acidogenic oral bacteria, may explain the lack of an in vitro inhibitory effect of xylitol on dental plaque samples.
TL;DR: There was no general effect of surfaces on attached bacterial activity, and attached cells may be more, or less, active than free-living cells, depending on the amino acid, its concentration, and substratum properties.
Abstract: Amino acid assimilation and electron transport system activity of a marine Pseudomonas sp. was evaluated to determine whether the activity of bacteria attached to solid surfaces differed from that of free-living bacteria or bacteria which had been attached but subsequently desorbed from the substratum (detached bacteria). Bacteria were allowed to attach to glass and to a range of plastic surfaces (Thermanox, polyvinylidene fluoride, polyethylene, polytetrafluoroethylene). Microautoradiography and staining with a tetrazolium salt to demonstrate electron transport system activity were used to compare the activity of these organisms with that of free-living or detached cells. The water-wettability of the surfaces was evaluated by measuring the advancing contact angle (θA) of water on each surface, to determine whether there was a relationship between activity and substratum hydrophilicity. There was an increase in the proportion of leucine-assimilating attached bacteria and in the proportion of attached cells demonstrating electron transport system activity with an increase in substratum θA, but the relationship between activity of attached and free-living cells depended on the substratum. Activity appeared to promote firm attachment, and detached bacteria assimilated fewer amino acids than did attached cells. There was no general effect of surfaces on attached bacterial activity, and attached cells may be more, or less, active than free-living cells, depending on the amino acid, its concentration, and substratum properties.
TL;DR: Airborne gram-negative bacteria, endotoxins, dust, and Aspergillus fumigatus were measured in four compost plants in Sweden and found that at sites where material was processed, the number of airborne A. fumgatus exceeded 10(6)/m3, whereas the number in the countryside was usually lower.
Abstract: Airborne gram-negative bacteria, endotoxins, dust, and Aspergillus fumigatus were measured in four compost plants in Sweden. At sites where material was processed, the number of airborne A. fumigatus exceeded 10(6)/m3, whereas the number of gram-negative bacteria was usually lower. Dust levels were moderate, and endotoxin levels were well below 0.5 micrograms/m3. Medical studies to evaluate the effects of this type of microbial exposure are recommended.
TL;DR: A new pyridonecarboxylic acid derivative with broad and potent antibacterial activity, AT-2266 inhibited some gram-positive bacteria, such as staphylococci and Bacillus subtilis, and most gram-negative bacteria, including Serratia marcescens, Pseudomonas aeruginosa, Haemophilus influenzae, and Campylobacter jejuni.
Abstract: AT-2266, 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-1,8-naphthyridine-3 -carboxylic acid, is a new pyridonecarboxylic acid derivative with broad and potent antibacterial activity. It inhibited some gram-positive bacteria, such as staphylococci and Bacillus subtilis, and most gram-negative bacteria, including Serratia marcescens, Pseudomonas aeruginosa, Haemophilus influenzae, and Campylobacter jejuni, at concentrations of 0.1 to 0.78 microgram/ml, and most gram-positive bacteria, glucose-nonfermenters, and Mycoplasma pneumoniae at concentrations of 1.56 to 12.5 micrograms/ml. Most of the clinical isolates tested were as susceptible to AT-2266 as were laboratory strains. The antibacterial potency of AT-2266 was higher than those of pipemidic acid and nalidixic acid and similar to that of norfloxacin. AT-2266 was not cross-resistant with antibiotics and inhibited most highly nalidixic acid-resistant bacteria at concentrations of 1.56 to 3.13 micrograms/ml. Its activity was barely affected by the addition of horse serum or sodium cholate but weakened by lowering the medium pH or increasing the inoculum size. AT-2266 was bactericidal at concentrations near its minimal inhibitory concentrations. Frequencies of mutants resistant to 10 micrograms of AT-2266 per ml were lower than 4.0 x 10(-9).
TL;DR: It is doubtful whether fish fermentation can be utilised on an industrial scale without improving the technique, which consists of the selection and use of psychotrophic lactic acid fermenters and commercially acceptable inhibitors of proteolytic activity and yeast growth.
Abstract: Silage fermentation of minced fish and fish offal after inoculation with cereals prefermented with Pediococcus acidilactici and Lactobacillus plantarum initiates a rapid fall in pH to below 4.5 within 30 h, and the content of competing gram-negative fermenters and fish pathogens, such as Vibrio anguillarum and Aeromonas salmonicida, is eliminated. The addition of 0.1% sorbic acid inhibits the growth of yeasts during the initial fermentation period and during storage but does not affect the lactic acid fermentation. Degradation of nitrogen components proceeds during storage and is manifested as an increase in volatile basic nitrogen compounds, amino acids and peptides. These substances increase the pH and/or force the bacteria to produce more acid. The rate of production of these basic substances is mainly temperature-dependent and cannot be attributed to microbial activity. The proteolytic activity is mainly caused by tissue proteases (e.g., cathepsins) and, to a lower degree, by gut proteases. It is doubtful whether fish fermentation can be utilised on an industrial scale without improving the technique. Such improvements consist of the selection and use of psychotrophic lactic acid fermenters and commercially acceptable inhibitors of proteolytic activity and yeast growth.