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PubMed2026

Investigating AHL-associated quorum sensing impact on antibiotic-driven resistome expansion in anaerobic fermentation microbiomes: Metagenomic insights.

Previous studies have demonstrated that quorum sensing (QS) can mitigate the impact of antibiotics on environmental microbial communities. Metagenomic analysis was used to examine AHL effects on the resistome in anaerobic fermentation microbiomes under antibiotic stress in this research. AHLs reduced ARGs, MGEs, and phage abundance compared to antibiotic-only samples following the addition of high concentrations (500 nmol/L) of AHLs. Phages and integrons played pivotal roles in shaping the resistome. Escherichia coli, Vibrio cholerae, and Pseudomonas aeruginosa were key targets affected by AHLs. Both the assembled environmental metagenomes and the complete genomes of isolated bacteria consistently support the broad potential of quorum-sensing systems in mediating the dissemination or regulation of resistome spreading. Quorum sensing systems are very likely to affect microbial community resistomes by regulating the phageome. These insights are valuable for refining fermentation and waste management processes, offering potential in environmental restoration and possibly curbing the spread of resistance genes.

Quorum Sensing↗
PubMed1975

Studies on the energy metabolism during anaerobic fermentation of glucose by baker's yeast.

As a result of the intimate association of ADP phosphorylation with alcoholic fermentation, resulting in the synthesis of 2 mole ATP per mole glucose fermented, it may be calculated that a minimum of 672 mucal heat development may be expected for every mm-3 CO2 developed during alcoholic fermentation. When all ATP produced would be fully de-phosphorylated to ADP + Pi (e.g. by ATP-ase activity) a maximum heat development of 1200 mucal per mm-3 CO2 could be expected. Using the LKB-Flow-Microcalorimeter for measurement of heat development and at the same time the Warburg technique for measuring CO2 development during anaerobic glucose fermentation of a baker's yeast suspension, the heat development per mm-3 CO2 produced was calculated over a fermentation period of 90 min. Maintenance of strict anaerobic conditions in the Flow-Microcalorimeter vessel was complicated by diffusion of traces of oxygen via the Teflon transport lines, resulting in excessive heat development values, not representative for the alcoholic fermentation. This problem could be circumvented by removal of traces of oxygen by means of addition of the enzyme glucose-oxidase. Poisoning the respiratory enzyme system of the yeast by addition of KCN or azide, or using respiratory-deficient mutants of the yeast also resulted in heat development values, inherent with alcoholic fermentation. The values obtained were very close to the minimum of 672 mucal per mm-3 CO2, at least during the initial phases of fermentation, indicating that ADP regeneration from ATP, essential for maintaining the high fermentation rate, is not primarily the result of ATP-ase activity, but must be due to participation of ATP in energy-requiring synthetic reactions.

Adenosine Diphosphate↗
PubMed1979

Relationship between steps in 8-anilino-1-naphthalene sulfonate (ANS) fluorescence and changes in the energized membrane state and in intracellular and extracellular adenosine 5'-triphosphate (ATP) levels following bacteriophage T5 infection of Escherichia coli.

The addition of bacteriophage T5 to anaerobic, fermenting cells of Escherichia coli B or K-12 in the presence of 8-anilino-1-naphthalene sulfonate (ANS), N-phenylnaphthyl-1-amine (NPN), or dansyl ethylamine causes the fluorescence of these probes to rise in two steps, the first occurring immediately upon addition, the second delayed by 6 min. The conditions necessary for observing this phenomenon are defined (cell density, probe concentration, substrate, absence of an electron acceptor, multiplicity of infection, growth, and harvesting conditions). The magnitudes of the first and second steps in fluorescence are dependent upon the multiplicity of infection; the timing of the steps is not. The first step correlates with a breakdown in the potassium or rubidium permeability barrier of the cells, and it occurs either aerobically or anaerobically, with fermentable or nonfermentable substrates. The second step occurs only with cells that are without an available electron acceptor, are fermenting, and which have a functional membrane-bound, Ca2+-dependent adenosine triphosphatase (ATPase). The results are consistent with disturbance of energization of the cell membrane by the membrane-bound ATPase at the time of the second step in fluorescence. No changes in the intracellular level of adenosine 5'-triphosphate (ATP) was seen, whereas the extracellular level increased sharply, starting 3--6 min after phage addition. The quantity of ATP found in the medium by 30 min after infection amounted to about four times the amount present inside the cells at the time of infection. The quantity and rate of efflux of ATP was similar under aerobic and anaerobic conditions.

Adenosine Triphosphate↗
PubMed1976

[Fermentation of pyruvate by 7 species of phototrophic purple bacteria].

The dark, anaerobic fermentation of pyruvate under growth conditions was examined with the following species of phototrophic purple bacteria: Rhodospirillum rubrum strains Ha and S1, Rhodopseudomonas gelatinosa strain 2150, Rhodopseudomonas acidophila strain 7050, Rhodopseudomonas palustris strain ATCC 17001, Rhodopseudomonas capsulata strains Kb1 and 6950, Rhodopseudomonas sphaeroides strain ATCC 17023, and Chromatium vinosum strain D. Fermentation balances were established for all experiments. Under fermentative conditions cell protein and dry weight increased only slightly, if at all. The species differed considerably in their fermentative activity; R. rubrum and R. gelatinosa exhibited the highest rates (2-8 mumoles pyruvate/mg protein-h). R. acidophila and R. capsulata showed an intermediate fermentation rate (0.4--2.0 mumoles pyruvate/mg protein-h), while the other strains tested fermented at quite low rates (0.2-0.4 mumoles pyruvate/mg protein-h). The extremes of fermentation times were from 30-380 hours. Based on the products of fermentation which were formed in addition to acetate, formate, and CO2, the species can be grouped as follows: a) R. rubrum, R. gelatinosa, and R. sphaeroides additionally form propionate. b) R. gelatinosa, R. palustris, R. capsulata, R. sphaeroides, and C. vinosum additionally form lactate. R. palustris also produces butyrate. c) R. acidophila and R. capsulata additionally form much 2,3-butanediol, acetoin, and diacetyl. Small amounts of acetoin were formed by the rest of the strains. A comparison of the fermentation of pyruvate by normal and starved cells (4 days in the light without a carbon source) of R. rubrum and R. gelatinosa shows that the latter ferment more slowly and produce less acetate and formate, but more propionate or lactate. The fermentation of pyruvate by R. rubrum was also studied in cultures in which the pH fell (7.2--6.6). Compared with the fermentation at neutral pH (7.3, 7.4), the following differences were found: a slower fermentation rate, an increased production of dry weight, an increased formation of propionate, but a reduced formation of acetate and a very low production of formate.

Acetates↗
PubMed1978

Levels of coenzyme A--glutathione mixed disulfide in Escherichia coli.

The pool of coenzyme A--glutathione mixed disulfide (CoASSG) rapidly increased 2.0 times in response to oxygen starvation and 1.5 times in response to glucose starvation but did not change following ammonia starvation. The increase in the CoASSG pool resulted from an increase in the CoASSG fraction of the CoA pool from 42 to 66--93%. Fluoride, cyanide, chloramphenicol, and rifampicin all caused similar increases. Aerobic growth on fermentable sugars resulted in CoASSG making up 40--55% of the CoA pool while growth on nonfermentable carbon sources or anaerobic fermentation resulted in CoASSG replacing acetyl CoA and free CoA to make up 85--95% of the CoA pool. The CoASSG:ATP ratio varied inversely with the growth rate in two groupings of carbon sources made up of either fermentable or nonfermentable molecules. Cultures grown aerobically on fermentable sugars exhibited a lower CoASSG:ATP ratio reflecting the lower proportion of CoASSG in the CoA pool.

Ammonia↗
PubMed1978

Effect of inhibitors on acid production by baker's yeast.

Glucose-induced acid extrusion, respiration and anaerobic fermentation in baker's yeast was studied with the aid of sixteen inhibitors. Uranyl(2+) nitrate affected the acid extrusion more anaerobically than aerobically; the complexing of Mg2+ and Ca2+ by EDTA at the membrane had no effect. Inhibitors of glycolysis (iodoacetamide, N-ethylmaleimide, fluoride) suppressed acid production markedly, and so did the phosphorylation-blocking arsenate. Fluoroacetate, inhibiting the citric-acid cycle, had no effect. Inhibition by uncouplers depended on their pKa values: 2,4,6-trinitrophenol (pKa 0.4) less than 2,4-dinitrophenol (4.1) less than azide (4.7) less than 3-chlorophenylhydrazonomalononitrile (6.0). Inhibition by trinitrophenol was only slightly increased by its acetylation. Cyanide and nonpermeant oligomycin showed practically no effect; inhibition by dicyclohexylcarbodiimide was delayed but potent. The concentration profiles of inhibition of acid production differed from those of respiration and fermentation. Thus, though the acid production is a metabolically dependent process, it does not reflect the intensity of metabolism, except partly in the first half of glycolysis.

Acids↗
PubMed1978

Bioenergetic aspects of aerobic glucose metabolism of Escherichia coli K-12 under varying specific growth rates and glucose concentrations.

An attempt was made to find a bioenergetical explanation for the differential effect of specific growth rate and glucose concentration on glucose metabolism of Escherichia coli K-12 with the help of 2,4-dinitrophenol (DNP). The effect of DNP on biomass occurred only at high glucose concentrations. The presence of this uncoupler strongly stimulated glucose uptake rates and oxygen uptake rates, but repressed severly Yg values. Increase in glucose concentration, however, sharply decreased QO2. The amount of oxygen required for maintenance was not affected by DNP, but Yomax values were much lower in the presence of DNP. The results are discussed and it is suggested that aerobic fermentation is caused by a severe reduction of site 1 of the respiratory chain region, whereas biomass formation is affected by repression of the terminal cytochrome a2. In comparing the effect of glucose on biomass formation at similar Qglucose levels aerobic and anaerobic fermentation, repression occurred in both cases at glucose concentrations of 0.3% and above. Although the analyses of 15 enzymes established the metabolic differences, the repression of growth was common to both fermentation types.

Aerobiosis↗
PubMed1978

Use of a rapid fermentation test for indentification of anaerobic bacteria.

Rapid fermentation tests of carbohydrates were performed on 84 strains of anaerobic bacteria, and the result is compared with a commercially available micromultitest, API. An overall correlation of 87% was achieved between the two systems. The rapid fermentation test is easy to perform, since it is done aerobically, and easy to read. This study shows that RFT is useful in routine diagnosis of anaerobic bacteria, if it is used in combination with other relevant biochemical tests, morphologic examination, and gas chromatography.

Anaerobiosis↗
PubMed1978

Changes in fluorescence of 8-anilino-1-naphthalene sulfonate after bacteriophage T5 infection of Escherichia coli. Initial fluorescence rise coincides with onset of rubidium efflux.

Escherichia coli cells pre-loaded with 86Rb+ begin to lose 86Rb+ immediately after phage T5 addition. The loss proceeds with negative-exponential (first-order) kinetics for up to approximately 15 min after phage addition. The constant which characterizes the rate of loss increases with increasing numbers of infecting phage per cell. It is known that anaerobic, fermenting cells of E. coli show a two-step increase in 8-anilino-1-naphthalene sulfonate (ANS) fluorescence upon infection with bacteriophage T5; the first rise begins immediately upon phage addition, the second 6 min later. The onset of 86Rb+ release, therefore, is correlated with the first fluorescence rise with respect to timing and response to the multiplicity of infection.

Aerobiosis↗
PubMed1977

Comparison of rabbit and pig plasma in the tube coagulase test.

A total of 627 clinical isolates of Micrococcaceae were characterized accoridng to their ability to coagulate rabbit and pig plasma, produce thermostable nuclease, and anaerobically ferment glucose and mannitol. By using these characteristics, 416 of the isolates were classified as Staphylococcus aureus and 211 as non-S. aureus. All 416 strains produced a 3 to 4+ clot formation in heparinized pig plasma, whereas 415 isolates produced a similar reaction in citrated rabbit plasma. All of the S. aureus strains possessed a thermostable nuclease, whereas only four of the non-S. aureus isolates exhibited this characteristic. The results obtained using heparinized pig plasma were almost identical to those obtained with commercial rabbit plasma.

Anaerobiosis↗
PubMed1977

Anaerobic degradation of cellulose by mixed culture.

A mixed culture in which cellulose is capable of being converted to methane and carbon dioxide was obtained from an inoculum procured from a sewage-treatment plant and maintained in a synthetic medium containing tissue paper and an inorganic salt and vitamin mixture. The culture was tested for its ability to degrade 12 different paper and cotton products under batch conditions in 3-l anaerobic fermenters. This culture degraded 6-8 mmol/l per week of cellulose, expressed as glucose equivalents, with total gas yields of 0.3 m3/kg of cellulose degraded. The gas produced contained between 56 and 59% of methane. Maximum cellulose degradation occurred at chemical oxygen demand:nitrogen:phosphorus level of 80:5:1 and was adversely affected by high stirring rate. Also the presence of higher proportions of lignin in cellulose products adversely affected the ability of this culture to degrade cellulose.

Anaerobiosis↗
PubMed2026

Enhancing the fiber degradation efficiency in dairy cattle rumen through engineered bacterial communities.

BACKGROUND: The rumen functions as an anaerobic fermentation chamber, housing microorganisms with cellulolytic and proteolytic capabilities that facilitate feed utilization. Fiber-degrading bacteria possess the capability to enhance the productivity of cellulolytic feed. The application of omics technologies has greatly improved our understanding of the rumen microbiome. Determining microbial composition and functional patterns in the rumen does not equate to a comprehensive exploration of rumen microbial resources and their mechanisms of action. This study seeks to integrate high throughput 16S rRNA data with information on culturomics, cellulolytic activities, nutrition, and synthetic microbial communities (SynCom) engineering. The objective is to evaluate the relationship between rumen microbial activity and fiber utilization efficiency in cattle, ultimately aiming to develop a more powerful intervention strategy for the ruminant industry. RESULTS: The enrichment culture with various carbon sources led to significant alterations in the composition and structure of rumen microbiota, particularly enhancing those associated with carbohydrate metabolism. Employing the culturomics methodology, 896 strains from 78 species (including 8 novel species) were isolated, resulting in a 10.1% isolation rate relative to the rumen bacterial community. Among them, 35 strains demonstrated boosted cellulose-degrading capability on plates, while 25 exhibited the ability to degrade hemicellulose as well. SynComs of these candidates were prepared based on the ratio observed in rumen microbiota exhibiting high cellulolytic performance. SynCom 3 improved the neutral detergent fiber degradation (NDFD) by 20.39% averagely. Additionally, both in vitro and in situ assessments indicated that the optimization of dose/strain in SynCom 3 significantly improved the in vitro NDFD by 20.56% and increased the in situ NDFD by 7.81%, along with the acidic detergent fiber (ADF, + 11.47%). Genomic analysis revealed that the SynCom 3 functioned well in fiber degradation through the synergistic action of key carbohydrate-active enzymes. CONCLUSIONS: This study strengthens rumen microbiome research by integrating omics and SynCom engineering within a microbiota-bacteria-enzymes-genes framework, revealing the significance of enzymatic synergy in carbohydrate metabolism. The findings establish a framework for utilizing low-abundance microbes and engineering functional consortia, which are crucial for improving ruminant feed utilization and biomass conversion. Future research should investigate the transcriptomic profiles and the metabolic cross-feeding mechanisms of fiber-degrading strains in the rumen. Video Abstract.

Animals↗
PubMed1979

The isolation of urease-negative strains of Yersinia enterocolitica.

Three urease-negative Y. enterocolitica strains of biotype 2 have been isolated from stool and urine of healthy persons. They were diagnosed on an isolation medium used routinely in the bacteriological laboratory of the Regional Station of Hygiene in Ceské Budĕjovice for isolation and diagnosis of gram-negative facultatively anaerobic-fermenting rods. An important characteristic was the smell of the culture, typical of all the indole-positive strains of Y. enterocolitica.

Adult↗
PubMed1975

Intestine of Ascaris: oxygen consumption, fermentation acids, and anaerobic synthesis of protein.

The oxygen uptakes by pieces of gut from the porcine roundworm, Ascaris suum, under Po2 10 to 710 torr were from 0.6 to 3.0 mul/mg dry wt/hr (Qo2). Increasing concentrations of tissue, 30 to 90 mg (dry wt/3 ml) decreased Qo2 in air from 1.9 to 1.1 and only technical grade catalase was found to relieve this inhibition. Conversely aerobic fermentation, judged by acid production, was directly proportional to the amount of tissue present: the acids from this fermentation were 2-methyl-butyric (1% of the total), succinic (8%), propionic (40%), and acetic (51%). Glucose did not increase Qo2 but it doubled the incorporation of labeled carbon into protein from glycine-1-14C. Judged by this, protein synthesis proceeded at the same rate under low Po2 (0.01 torr) as under air.

Anaerobiosis↗
PubMed1978

[Differential diagnosis of enterococci].

The most stable differential signs of enterococci are: growth in the medium at pH 10.2, growth in broth containing 40% bile, citrate utilization, resistance to 0,05% potassium tellurite, 2, 3, 5-triphenyltetrazolium chloride (TTC) reduction, the staining of colonies (plaques) on a medium with manganese, iron and zinc salts, glycerine fermentation under anaerobic conditions, mannite fermentation, the presence of hemolysin, of the proteolytic enzyme, and mobility. Combined differential-diagnostic nutrient medium permits to determine simultaneously 5 enterococci signs--resistance to nalidixic acid and to crystal violet, TTC reduction, hemolytic and proteolytic activity. The suggested scheme of enterococci laboratory diagnosis including a set of hard nutrient media poured into multisection Petri dish is simple reliable and accessible for any bacteriological laboratory.

Culture Media↗