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The waste generated by the mezcal and seafood restaurant industries has significant negative environmental impacts on soils, water, and air. However, these waste materials offer the potential for methane production through anaerobic digestion. This research focuses on evaluating a methodological strategy that involves using an enriched inoculum, co-digesting waste materials, and applying specific pretreatment (chemical, thermal, and adjusting the volumetric ratio of residues) to produce biogas with a high methane content, as assessed through the Biochemical Methane Potential (BMP) test. The results demonstrate that the enriched inoculum used in the test exhibited a pH of 8.18, an Alkalinity of 31 g CaCO3/L, and an alpha (α) ratio of 0.75. The BMP test was conducted over 29 days. In the most successful test, which involved pretreatment at a temperature of 50 °C, a residue ratio of 1 VSW (Volume of Seafood Waste)/2 VMV (Volume of Mezcal Vinasses), and a pH of 6.5, we achieved a methane production of 1420.51 ± 0.038 N mL CH4, with a biogas containing 81.5% methane. This process also yielded 175.37 N mL CH4 per gram of Volatile Solids (VS) and a degradation kinetic constant of 0.14 1/d. Through the methodological strategy used with the combination of an enriched and stabilized inoculum, the co-digestion of the waste for nutrient complementation, and the application of pretreatments, it was achieved that the different stages that constitute the anaerobic process allowed for the establishment of optimal conditions for the generation of biogas with a high methane content. [ABSTRACT FROM AUTHOR]

Photogeneration of hydrogen in microalgae is thought to be among the mechanisms increasing their resilience to stresses including those caused by nutrient deprivation by re-routing the flow of electrons and reducing power in the cell. Metabolism of phosphorus (P), an essential nutrient, and its reserve forms such as polyphosphate (PolyP), is affected by and plays a role in the responses to diverse stresses, too. However, the potential interplay of the capability of photogeneration of hydrogen and turnover of phosphorus-rich inclusions in stressed microalgae cells so far escaped the attention of researchers. Here, we present a quantitative ultrastructural view of the turnover of P-rich inclusions in the model microalga Chlamydomonas reinhardtii strains, the parent strain CC-425 and its hydEF-1 mutant lacking hydrogenase activity as a function of sulfur and oxygen availability in the medium. In addition to the electron microscopy cell image analysis of the studied strains, we followed the elemental composition of the inclusions in different (sub) compartments of the cells obtained with energy dispersive X-ray spectroscopy. The stress caused by sulfur deprivation and subsequent transition of the microalgae culture to anaerobic conditions declined the size of phosphorus-containing inclusions but increased their number in the parent strain. Overall, the accumulation of the phosphorus-rich inclusions in hydEF-1 mutant was much lower than in the fully functional parent strain regardless of the cultivation conditions. We believe that impaired hydrogenase activity and correspondingly reduced sink of electrons and reducing power in the mutant strain indirectly affects the turnover of P and its reserves in the cell. These effects were manifested by the changes in the abundance, morphology, and elemental composition of the P-containing inclusions. We hypothesized that the sulfur-deprivation stress increased the initiation of the biosynthesis of PolyP chains, but their elongation and hence the formation of large PolyP-containing inclusions was hindered by anaerobiosis. [ABSTRACT FROM AUTHOR]

Chaperone proteins have crucial roles to play in all animal species and are involved in mediating both the folding of newly synthesized peptides into their mature conformation, the refolding of misfolded proteins, and the trafficking of proteins between subcellular compartments. These highly conserved proteins have particularly important roles to play in dealing with disruptions of the proteome as a result of environmental stress since abiotic factors, including temperature, pressure, oxygen, water availability, and pollutants can readily disrupt the conformation and/or function of all types of proteins, e.g., enzymes, transporters, and structural proteins. The current review provides an update on recent advances in understanding the roles and responses of chaperones in aiding animals to deal with environmental stress, offering new information on chaperone action in supporting survival strategies including torpor, hibernation, anaerobiosis, estivation, and cold/freeze tolerance among both vertebrate and invertebrate species. [ABSTRACT FROM AUTHOR]

The microaerophilic human parasite Trichomonas vaginalis causes infections in the urogenital tract and is one of the most often sexually transmitted pathogens worldwide. Due to its anaerobic metabolism, it has to quickly remove intracellular oxygen in order to avoid deactivation of essential metabolic enzymes such as oxygen-sensitive pyruvate:ferredoxin oxidoreductase (PFOR). Two major enzyme activities which are responsible for the removal, i.e. reduction, of molecular oxygen have been identified in T. vaginalis flavin reductase, formerly designated NADPH oxidase, which indirectly reduces oxygen to hydrogen peroxide via flavin mononucleotide (FMN), and NADH oxidase which reduces oxygen to water. Flavin reductase has been identified and characterized at the gene level as well as enzymatically, but NADH oxidase has so far only been characterized enzymatically with enzyme isolated from T. vaginalis cell extracts. In this study, we identified NADH oxidase by mass spectrometry after isolation of the enzyme from gel bands positively staining for NADH oxidase activity. In strain C1 (ATCC 30001) which is known to lack NADH oxidase activity completely, the NADH oxidase gene has a deletion at position 1540 of the open reading frame leading to a frame shift and, as a consequence, to premature termination of the encoded polypeptide. [ABSTRACT FROM AUTHOR]

This study analyses the induction and repression of nitrate reduction activity in a batch culture of Idiomarina strain cos21. On a change from aerobic to anaerobic respiration, the culture entered a stationary phase. The onset of this phase showed 3.75 fold increase in mRNA levels for the nitrate reductase enzyme. mRNA accumulated very rapidly during a short period, after which its overall concentration declined to reach a lower value. The level of nitrite reductase protein reached a maximum value at 36 h of growth when the oxygen concentration dropped below 10 µM. The data set provided here confer new insights into the understanding of the physiological response of Idiomarina strain cos21 to change in oxygen concentration allowing the bacterium to survive and adapt to a new environment by dissimilatory reduction of nitrate to nitrite, which serves to provide energy as the bacteria adapt to anaerobiosis. Main strategy used here is to induce, measure, and track the expression of microbial genes, while they grow in culture conditions to better mimic interaction in a natural environment. This study will help us with a better understanding of the nitrate reduction process in the oxygen minimum zone. [ABSTRACT FROM AUTHOR]

Ocean warming and acidification are two important environmental drivers affecting marine organisms. Organisms living at high latitudes might be especially threatened in near future, as current environmental changes are larger and occur faster. Therefore, we investigated the effect of hypercapnia on thermal tolerance and physiological performance of sub-Arctic Mytilus edulis from the White Sea. Mussels were exposed (2 weeks) to 390 µatm (control) and 1120 µatm CO2 (year 2100) before respiration rate (MO2), anaerobic metabolite (succinate) level, haemolymph acid-base status and intracellular pH (pHi) were determined during acute warming (10-28 °C, 3 °C over night). In normocapnic mussels, warming induced MO2 to rise exponentially until it levelled off beyond a breakpoint temperature of 20.5 °C. Concurrently, haemolymph PCO2 rose significantly > 19 °C followed by a decrease in PO2 indicating the pejus temperature (TP, onset of thermal limitation). Succinate started to accumulate at 28 °C under normocapnia defining the critical temperature (TC). pHi was maintained during warming until it dropped at 28 °C, in line with the concomitant transition to anaerobiosis. At acclimation temperature, CO2 had only a minor impact. During warming, MO2 was stimulated by CO2 resulting in an elevated breakpoint of 25.8 °C. Nevertheless, alterations in haemolymph gases (> 16 °C) and the concomitant changes of pHi and succinate level (25 °C) occurred at lower temperature under hypercapnia versus normocapnia indicating a downward shift of both thermal limits TP and TC by CO2. Compared to temperate conspecifics, sub-Arctic mussels showed an enhanced thermal sensitivity, exacerbated further by hypercapnia, indicating their potential vulnerability to environmental changes projected for 2100. [ABSTRACT FROM AUTHOR]

When soils are water saturated, the reduced forms of soil nitrogen such as ammonium are favored. Under anaerobiosis, ammonium production has been explained by several mechanisms such as organic nitrogen mineralization (ONM), dissimilatory nitrate reduction to ammonium (DNRA) and the release of adsorbed ammonium during microbial reduction of iron oxides (MRFeO). Nevertheless, in anaerobic soils the dominance of one mechanism over the others is still debated. Nitrogen appears to influence the reproductive dynamics of Mauritia flexuosa, the dominant canopy species of the “morichal” ecosystem. Even though M. flexuosa has been classified as “vulnerable”, ammonium production in morichal soils is not well understood. Considering this, we evaluated in a morichal soil from SE Venezuela, the mechanisms associated with ammonium production under anaerobic conditions. To this end, we designed an anaerobic incubation experiment to follow over time the concentrations of nitrate, extractable ferrous iron and ammonium together with the activity of β-glucosaminidase as an index of N mineralization. To account for the relative importance of ONM, DNRA and MRFeO on ammonium production, we used multiple linear regression models. The results showed that the three mechanisms are involved in ammonium production. However, ONM is the main source of ammonium in the initial 15 days of soil incubation, while MRFeO explains ammonium produced after 15 days of soil incubation. However, under climate change scenarios these mechanisms may be altered, thereby increasing the N limitation of morichales and consequently its vulnerability. Since morichales are threatened ecosystems, that play a key ecological, economic and cultural role, studies on the soil nitrogen dynamics are important to design and evaluate effective management, conservation and protection strategies. This study can be a relevant contribution in this area. [ABSTRACT FROM AUTHOR]

The budding yeast Saccharomyces cerevisiae plays an important role in biotechnological applications, ranging from fuel ethanol to recombinant protein production. It is also a model organism for studies on cell physiology and genetic regulation. Its ability to grow under anaerobic conditions is of interest in many industrial applications. Unlike industrial bioreactors with their low surface area relative to volume, ensuring a complete anaerobic atmosphere during microbial cultivations in the laboratory is rather difficult. Tiny amounts of O2 that enter the system can vastly influence product yields and microbial physiology. A common procedure in the laboratory is to sparge the culture vessel with ultrapure N2 gas; together with the use of butyl rubber stoppers and norprene tubing, O2 diffusion into the system can be strongly minimized. With insights from some studies conducted in our laboratory, we explore the question ‘how anaerobic is anaerobiosis?’. We briefly discuss the role of O2 in non-respiratory pathways in S. cerevisiae and provide a systematic survey of the attempts made thus far to cultivate yeast under anaerobic conditions. We conclude that very few data exist on the physiology of S. cerevisiae under anaerobiosis in the absence of the anaerobic growth factors ergosterol and unsaturated fatty acids. Anaerobicity should be treated as a relative condition since complete anaerobiosis is hardly achievable in the laboratory. Ideally, researchers should provide all the details of their anaerobic set-up, to ensure reproducibility of results among different laboratories. [ABSTRACT FROM AUTHOR]

Cyanide is one of the most toxic chemicals for living organisms described so far. Its toxicity is mainly based on the high affinity that cyanide presents toward metals, provoking inhibition of essential metalloenzymes. Cyanide and its cyano-derivatives are produced in a large scale by many industrial activities related to recovering of precious metals in mining and jewelry, coke production, steel hardening, synthesis of organic chemicals, and food processing industries. As consequence, cyanide-containing wastes are accumulated in the environment becoming a risk to human health and ecosystems. Cyanide and related compounds, like nitriles and thiocyanate, are degraded aerobically by numerous bacteria, and therefore, biodegradation has been offered as a clean and cheap strategy to deal with these industrial wastes. Anaerobic biological treatments are often preferred options for wastewater biodegradation. However, at present very little is known about anaerobic degradation of these hazardous compounds. This review is focused on microbial degradation of cyanide and related compounds under anaerobiosis, exploring their potential application in bioremediation of industrial cyanide-containing wastes. [ABSTRACT FROM AUTHOR]

Moisture response functions for soil microbial carbon (C) mineralization remain a critical uncertainty for predicting ecosystem-climate feedbacks. Theory and models posit that C mineralization declines under elevated moisture and associated anaerobic conditions, leading to soil C accumulation. Yet, iron (Fe) reduction potentially releases protected C, providing an under-appreciated mechanism for C destabilization under elevated moisture. Here we incubate Mollisols from ecosystems under C3/C4 plant rotations at moisture levels at and above field capacity over 5 months. Increased moisture and anaerobiosis initially suppress soil C mineralization, consistent with theory. However, after 25 days, elevated moisture stimulates cumulative gaseous C-loss as CO2 and CH4 to >150% of the control. Stable C isotopes show that mineralization of older C3-derived C released following Fe reduction dominates C losses. Counter to theory, elevated moisture may significantly accelerate C losses from mineral soils over weeks to months--a critical mechanistic deficiency of current Earth system models. [ABSTRACT FROM AUTHOR]

We analyzed the formation of biofilms by 7 strains of Campylobacter genus bacteria and 18 strains of Enterobacteriaceae genus bacteria that were isolated from plant and animal raw materials, from finished products, and swabs from the equipment of the food industry. Biofilm formation on glass plates, slides and coverslips, microtubes made of polymeric materials and Petri dishes, and polystyrene plates of different profiles were analyzed. When studying the process of films formation, different effects on bacterial populations were simulated, including variation of growth factor composition of culture media, technique of creating of anaerobiosis, and biocide treatment (active chlorine solutions in a concentration of 100 mg/dm). The formation of biofilms by the studied cultures was assessed by the formation of extracellular matrix stained with aniline dyes on glass and polystyrene surfaces after incubation; 0.1% crystal violet solution was used as the dye. The presence and density of biomatrix were assessed by staining intensity of the surfaces of contact with broth cultures or by optical density of the stained inoculum on a spectrophotometer. Biofilms were formed by 57% Campylobacter strains and 44% Enterobacteriaceae strains. The intensity of the film formation depended on culturing conditions and protocols, species and genus of studied isolates, and largely on adhesion properties of abiotic surfaces. In 30% of Enterobacteriaceae strains, the biofilm formation capacity tended to increase under the influence of chlorine-containing biocide solutions. Thus, we developed and tested under laboratory conditions a plate version of in vitro chromogenic model for evaluation of biofilm formation capacity of C. jejuni strains and studied stress responses to negative environmental factors. [ABSTRACT FROM AUTHOR]

Escherichia coli open reading frames ydiO and ydiQRST were identified as genes encoding components of the acyl-CoA dehydrogenase complex of anaerobic fatty acid β-oxidation. Individual or concomitant inactivation of fadE gene, encoding known aerobic acyl-CoA dehydrogenase, and ydiO and/or ydiQRST genes did not affect cellular growth on glucose as a sole carbon source. Aerobic growth on sodium oleate was observed only for the cells with intact fadE gene. With an alternative electron acceptor, the cells possessing intact fadE gene demonstrated anaerobic growth on sodium oleate irrespective of the presence or absence of ydiO and ydiQRST genes. For the fadE-deficient mutants, anaerobic growth on sodium oleate was observed only for cells with intact ydiO and ydiQRST genes, while the fadE/ ydiO and fadE/ ydiQRST mutants failed to grow under the similar conditions. [ABSTRACT FROM AUTHOR]

Dekkera bruxellensis is a non-conventional Crabtree-positive yeast with a good ethanol production capability. Compared to Saccharomyces cerevisiae, its tolerance to acidic pH and its utilization of alternative carbon sources make it a promising organism for producing biofuel. In this study, we developed an auxotrophic transformation system and an expression vector, which enabled the manipulation of D. bruxellensis, thereby improving its fermentative performance. Its gene ADH3, coding for alcohol dehydrogenase, was cloned and overexpressed under the control of the strong and constitutive promoter TEF1. Our recombinant D. bruxellensis strain displayed 1.4 and 1.7 times faster specific glucose consumption rate during aerobic and anaerobic glucose fermentations, respectively; it yielded 1.2 times and 1.5 times more ethanol than did the parental strain under aerobic and anaerobic conditions, respectively. The overexpression of ADH3 in D. bruxellensis also reduced the inhibition of fermentation by anaerobiosis, the 'Custer effect'. Thus, the fermentative capacity of D. bruxellensis could be further improved by metabolic engineering. [ABSTRACT FROM AUTHOR]

Lactate is produced in carbohydrate metabolism under anaerobic conditions. Lactic acidosis occurs when the production of lactate exceeds its removal. In post-mortem (PM) context, the lactic acidosis is difficult to interpret due to unknown pathophysiological factors prior to death and PM changes that may affect the lactate levels. We evaluated 1865 medico-legal autopsy cases where the quantitation of glucose, lactate, and ketone bodies was performed as a part of the cause of death (CoD) investigation. Lactate was shown to ascend in a logarithmic manner as the PM interval increased until a plateau was achieved approximately after 8-10 days PM, and the elevation was caused mainly by PM changes. The lactate level was higher than the mean in cases where the CoD was diabetes mellitus type 2 (DM2) or metformin poisoning. Although there was a correlation between metformin and lactate levels, our findings suggest the DM2 and its complications were the cause for elevated lactate levels rather than metformin, since the lactate levels were similar in DM2-associated deaths where no metformin was detected. Elevated lactate levels in PM samples rather referred to metabolic disturbances often caused by DM2. An assay to detect D-lactate in PM samples was described. [ABSTRACT FROM AUTHOR]

The anoxic saccharide-rich conditions of the earthworm gut provide an ideal transient habitat for ingested microbes capable of anaerobiosis. It was recently discovered that the earthworm Eudrilus eugeniae from Brazil can emit methane (CH4) and that ingested methanogens might be associated with this emission. The objective of this study was to resolve trophic interactions of bacteria and methanogens in the methanogenic food web in the gut contents of E. eugeniae. RNA-based stable isotope probing of bacterial 16S rRNA as well as mcrA and mrtA (the alpha subunit of methyl-CoM reductase and its isoenzyme, respectively) of methanogens was performed with [13C]-glucose as a model saccharide in the gut contents. Concomitant fermentations were augmented by the rapid consumption of glucose, yielding numerous products, including molecular hydrogen (H2), carbon dioxide (CO2), formate, acetate, ethanol, lactate, succinate and propionate. Aeromonadaceae-affiliated facultative aerobes, and obligate anaerobes affiliated to Lachnospiraceae, Veillonellaceae and Ruminococcaceae were associated with the diverse fermentations. Methanogenesis was ongoing during incubations, and 13C-labeling of CH4 verified that supplemental [13C]-glucose derived carbon was dissimilated to CH4. Hydrogenotrophic methanogens affiliated with Methanobacteriaceae and Methanoregulaceae were linked to methanogenesis, and acetogens related to Peptostreptoccocaceae were likewise found to be participants in the methanogenic food web. H2 rather than acetate stimulated methanogenesis in the methanogenic gut content enrichments, and acetogens appeared to dissimilate supplemental H2 to acetate in methanogenic enrichments. These findings provide insight on the processes and associated taxa potentially linked to methanogenesis and the turnover of organic carbon in the alimentary canal of methane-emitting E. eugeniae. [ABSTRACT FROM AUTHOR]

During development crustaceans experience a range of oxygen tensions (PO) in their various developmental environments. Therefore, it is likely that they developed varying strategies to respond to hypoxic events during their ontogeny. We investigated short-term responses to various oxygen levels in early life stages of two anomuran decapods Petrolisthes laevigatus and Lithodes santolla that develop in different habitats. Embryos and juveniles of P. laevigatus inhabit the upper rocky intertidal and are regularly exposed to hypoxia during low tide, while larvae of this species inhabit well-oxygenated surface waters. L. santolla is a subtidal species that inhabits fjords and is frequently exposed to hypoxia due to stratification in this environment. Oxygen consumption (MO), lactate content, RNA/DNA ratio, lactate dehydrogenase and superoxide dismutase (SOD) activities were measured in embryos, larvae and juveniles after exposure to POs of 3-21 kPa for 24 h. Results indicated considerable variation in hypoxia tolerances among the ontogenetic stages of both species. Embryos of both species relied on anaerobiosis at all tested PO yet were able to regulate MO until 15 kPa. In contrast, larvae of L. santolla were oxyconformers, while those of P. laevigatus continued to oxyregulate in conjunction with a decrease in SOD activities in response to low PO. Juveniles of P. laevigatus were more sensitive to hypoxia than those of L. santolla as all tested parameters were affected at higher PO in the former. This study shows that aerobic and anaerobic metabolism, antioxidant defence and protein synthesis of early life stages are diverse and reflect the variety of inhabited environments. [ABSTRACT FROM AUTHOR]

Main conclusion: A 44-base-pair region in the Chlamydomonas reinhardtii LHCBM9 promoter is essential for sulphur responsiveness. The photosynthetic light-harvesting complex (LHC) proteins play essential roles both in light capture, the first step of photosynthesis, and in photoprotective mechanisms. In contrast to the other LHC proteins and the majority of photosynthesis proteins, the Chlamydomonas reinhardtii photosystem II-associated LHC protein, LHCBM9, was recently reported to be up-regulated under sulphur deprivation conditions, which also induce hydrogen production. Here, we examined the sulphur responsiveness of the LHCBM9 gene at the transcriptional level, through promoter deletion analysis. The LHCBM9 promoter was found to be responsive to sulphur deprivation, with a 44-base-pair region between nucleotide positions −136 and −180 relative to the translation start site identified as essential for this response. Anaerobiosis was found to enhance promoter activity under sulphur deprivation conditions, however, alone was unable to induce promoter activity. The study of LHCBM9 is of biological and biotechnological importance, as its expression is linked to photobiological hydrogen production, theoretically the most efficient process for biofuel production, while the simplicity of using an S-deprivation trigger enables the development of a novel C. reinhardtii-inducible promoter system based on LHCBM9. [ABSTRACT FROM AUTHOR]

We investigated epidermal peels from the leaves of pea ( Pisum sativum L.) consisting of a monolayer of the cells of two types: stomatal guard cells (GC) with chloroplasts and mitochondria and basic epidermal cells (EC) containing only mitochondria. As inducers of programmed cell death, we used KCN destroying the nuclei in GC and EC and chitosan that destroys nuclei only in EC. AgNO (10 μM) stimulated the destruction of nuclei in GC and EC induced by CN and suppressed chitosan-induced destruction of nuclei in EC. The destruction of nuclei in GC induced by CN occurred under aerobic conditions and was prevented under anaerobiosis. The destruction of nuclei in GC induced by (CN + Ag) occurred both under aerobic and anaerobic conditions and was not suppressed by antioxidants. Among the tested cations of metals (Ag+, Hg, Fe, Fe, Cu, and Mn), Ag turned out to be the most efficient in respect to the stimulation of cyanide-induced destruction of nuclei in GC. Half-maximum concentrations of Ag and Hg were equal to 4-5 μM. In epidermal peels treated with chitosan, GC were permeable to propidium iodide; however, the nuclei in GC (in contrast to EC) were not destructed in the presence of chitosan. It was concluded that Ag, acting as an electron acceptor during photosynthetic electron transfer in the chloroplasts from pea leaves, impeded the O evolution by the chloroplasts treated with ferricyanide or silicomolybdate as electron acceptors, impeded the consumption of O in the course of electron transfer from the (ascorbate + N,N,N′,N′-tetramethyl- p-phenylenediamine) to methylviologen and suppressed the production of reactive oxygen species (ROS) in GC and EC. [ABSTRACT FROM AUTHOR]

The diseases caused for Clostridium perfringens are generically called enterotoxemias because toxins produced in the intestine may be absorbed into the general circulation. C. perfringens type B, grown in batch fermentation, produced toxins used to obtain veterinary vaccines. Glucose in concentrations of 1.4-111.1 mM was used to define the culture medium. The minimum concentration for a satisfactory production of vaccines against clostridial diseases was 55.6 mM. Best results were brought forth by meat and casein peptones, both in the concentration 5.0 g l in combination with glucose and a culture pH maintained at 6.5 throughout the fermentation process. The production of lactic, acetic and propionic organic acids was observed. Ethanol was the metabolite produced in the highest concentration when cultures maintained steady pH of 6.5 with exception of cultures with initial glucose concentration of 1.4 mM, where the highest production was of propionic acid. Maximal cell concentration and the highest toxin title concomitantly low yield coefficient to organic acids and ethanol were obtained using basal medium containing 111.1 mM glucose under a controlled pH culture (pH) 6.5 in batch fermentations of C. perfringens type B. These data contribute to improve process for industrial toxin production allowing better condition to produce a toxoid vaccine. [ABSTRACT FROM AUTHOR]

Anaerobic/aerobic conditions affected bacterial community composition and the subsequent chlorophenols (CPs) degradation in biocathode microbial fuel cells (MFCs). Bacterial communities acclimated with either 4-chlorophenol (4-CP) or 2,4-dichlorophenol (2,4-DCP) under anaerobiosis can degrade the respective substrates more efficiently than the facultative aerobic bacterial communities. The anaerobic bacterial communities well developed with 2,4-DCP were then adapted to 2,4,6-trichlorophenol (2,4,6-TCP) and successfully stimulated for enhanced 2,4,6-TCP degradation and power generation. A 2,4,6-TCP degradation rate of 0.10 mol/m/d and a maximum power density of 2.6 W/m (11.7 A/m) were achieved, 138 and 13 % improvements, respectively compared to the controls with no stimulation. Bacterial communities developed with the specific CPs under anaerobic/aerobic conditions as well as the stimulated biofilm shared some dominant genera and also exhibited great differences. These results provide the most convincing evidence to date that anaerobic/aerobic conditions affected CPs degradation with power generation from the biocathode systems, and using deliberate substrates can stimulate the microbial consortia and be potentially feasible for the selection of an appropriate microbial community for the target substrate (e.g. 2,4,6-TCP) degradation in the biocathode MFCs. [ABSTRACT FROM AUTHOR]

Illumination of intact cells of Rhodobacter sphaeroides under anaerobic conditions has a dual effect on the redox state of the quinone pool. A large oxidation of the quinone pool is observed during the first seconds following the illumination. This oxidation is suppressed by the addition of an uncoupler in agreement with a light-induced reverse electron transfer at the level of the complex I, present both in the non-invaginated part of the membrane and in the chromatophores. At longer dark times, this illumination increases the reducing power of the cells leading to a significant reduction of the others reaction centers (RCs). From the observation that a significant proportion of RCs could be reduced by the preillumination without affecting the numbers of charge separation for the RCs, we conclude that there is no rapid thermodynamic equilibrium between the quinones present in the non-invaginated part of the membrane and those localized in the chromatophores. Under anaerobic conditions where the chromatophores quinone pool is fully reduced, we deduce, on the basis of flash-induced fluorescence kinetics, that the reduced RCs are exclusively reoxidized by the quinone generated at the Q site of the cyt bc complex. The supramolecular association between a dimeric RC-LHI complex and one cyt bc complex allows the confinement of a quinone between the RC-LHI directly associated to the cyt bc complex. [ABSTRACT FROM AUTHOR]

The effect of anaerobiosis on the induction of the xanthophyll cycle was investigated in Chlamydomonas reinhardtii. The results showed that, anaerobiosis obtained by either sulfur starvation or by bubbling nitrogen in the culture grown in complete medium induced the xanthophyll cycle even when cultures were exposed to low light conditions. The zeaxanthin content reached 35 mmol mol Chl a, after 110 h in anaerobic sulfur-starved cultures, and 30 mmol mol Chl a within 24 h in sulfur replete cultures bubbled with nitrogen. Both starved and non-starved cultures grown under aerobic conditions, did not exhibit any sizeable increase in the zeaxanthin content. Chlorophyll fluorescence measurements revealed a decrease in the maximum photochemical quantum yield of PSII (F/F) by more than 50 %. The chlorophyll fluorescence kinetics (OJIP) analysis showed a strong rise at the J-step indicating a strong reduction of Q. Our findings demonstrated that anaerobiosis in low light exposed cultures induced the xanthophyll cycle through a strong increase of the level of plastoquinone pool reduction, which was associated to the formation of a trans-thylakoid membranes proton gradient, while in dark anaerobic cultures, no appreciable induction of xanthophyll cycle could be observed, despite the sizeable increase in non-photochemical quenching. [ABSTRACT FROM AUTHOR]

Tangxun Lake is the largest urban lake in China, which is polluted by multiple wastewaters, and now is severely eutrophic. We detected diversity, abundance, and the coexistence of Candidatus Methylomirabilis oxyfera-like and anammox bacteria in different horizontal and vertical directions of the lake sediments through qPCR and clone library. Phylogenetic tree analysis showed that the Ca. Methylomirabilis oxyfera-like and anammox bacteria exhibited high diversity, and they belonged to group B-E and Ca. Brocadia genus, respectively. These two bacteria displayed higher diversity in polluted area than in other areas. Furthermore, they had great spatial variation of abundance both horizontally and vertically. The abundance of anammox bacteria was significantly higher than that of Ca. Methylomirabilis oxyfera-like bacteria. The stronger the human interference were, the higher abundances these two bacteria exhibited horizontally, whereas both their abundances and the ratio of anammox to Ca. Methylomirabilis oxyfera-like bacteria decreased with the increasing depth. Redundancy analysis indicated that nitrate was the most influential environmental factor to the abundance of these two bacteria. Ammonia, nitrite, total nitrogen, and organic matters were in positive correlation with the abundance of these two bacteria. Nitrate was slightly negatively correlated with the abundance of Ca. Methylomirabilis oxyfera-like bacteria, while it was positively correlated with that of anammox bacteria. Our results provided an insight into the effects of environmental factors such as ammonia, nitrite, and nitrate on the diversity and abundances of these two bacteria and theoretical basis for restoration of water., (© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

The healthy intestine is characterized by a low level of oxygen and by the presence of large bacterial communities of obligate anaerobes. Dysbiosis of the gut microbiota has been reported in patients suffering from inflammatory bowel diseases (IBDs), but the mechanisms causing this imbalance remain unknown. Observations have included a decrease in obligate anaerobes of the phylum Firmicutes and an increase in facultative anaerobes, including members of the family Enterobacteriaceae. The shift of bacterial communities from obligate to facultative anaerobes strongly suggests a disruption in anaerobiosis and points to a role for oxygen in intestinal dysbiosis. Proposals to evaluate this hypothesis of a role for oxygen in IBD dysbiosis are provided. If this hypothesis is confirmed, decreasing oxygen in the intestine could open novel means to rebalance the microbiota and could provide novel preventative or therapeutic strategies for IBD patients in whom current treatments are ineffective. [ABSTRACT FROM AUTHOR]

Red-eared slider turtles, Trachemys scripta elegans, can survive for several weeks without oxygen when submerged in cold water. We hypothesized that anaerobiosis is aided by adaptive up-regulation of the unfolded protein response (UPR), a stress-responsive pathway that is activated by accumulation of unfolded proteins in the endoplasmic reticulum (ER) and functions to restore ER homeostasis. RT-PCR, western immunoblotting and DNA-binding assays were used to quantify the responses and/or activation status of UPR-responsive genes and proteins in turtle tissues after animal exposure to 5 or 20 h of anoxic submergence at 4 °C. The phosphorylation state of protein kinase-like ER kinase (PERK) (a UPR-regulated kinase) and eukaryotic initiation factor 2 (eIF2α) increased by 1.43-2.50 fold in response to anoxia in turtle heart, kidney, and liver. Activation of the PERK-regulated transcription factor, activating transcription factor 4 (ATF4), during anoxia was documented by elevated atf4 transcripts and total ATF4 protein (1.60-2.43 fold), increased nuclear ATF4 content, and increased DNA-binding activity (1.44-2.32 fold). ATF3 and GADD34 (downstream targets of ATF4) also increased by 1.38-3.32 fold in heart and liver under anoxia, and atf3 transcripts were also elevated in heart. Two characteristic chaperones of the UPR, GRP78, and GRP94, also responded positively to anoxia with strong increases in both the transcript and protein levels. The data demonstrate that the UPR is activated in turtle heart, kidney, and liver in response to anoxia, suggesting that this pathway mediates an integrated stress response to protect tissues during oxygen deprivation. [ABSTRACT FROM AUTHOR]

The physiological role of nitrate as a protective factor against anaerobic stress was studied in experiments with tolerant to anoxia sugarcane ( Saccharum officibarum L.) callus lines obtained by in vitro selection in the absence of exogenous carbohydrates. Original cell lines, which were not subjected to selection and therefore more sensitive to oxygen shortage, served as a control. In these lines, anaerobic stress was created in the presence or absence of nitrate in nutrient medium. The presence of nitrate in nutrient medium increased markedly tolerance to anaerobic stress of both lines differing in their sensitivity to anaerobiosis. However, the degree of tolerance differed substantially in compared lines. In the presence of exogenous nitrate, in tolerant cells there were no signs of mitochondrial membrane destruction or degradation even after 72 h of anoxia, whereas in control cells 48-h anaerobic incubation led to the complete degradation of mitochondrial membranes and membranes of other organelles. It is concluded that significant increase in the tolerance of S. officinarum cells in the process of in vitro selection most likely occurred due to induction and stimulation of not only the processes of glycolysis and fermentation, but also nitrate and maybe nitrite utilization. [ABSTRACT FROM AUTHOR]

Alstroemeria is multiplied in vitro by forced outgrowth of lateral rhizomes from rhizome explants. The multiplication rate is very low because of strong apical dominance and poor rhizome growth. We report here that moderate abiotic stresses stimulate both rhizome growth and outgrowth of lateral rhizomes, and accordingly increase multiplication. Rhizome explants were exposed to heat by a hot-water treatment (HWT) or by a hot-air treatment. Both increased rhizome growth when applied for 1 or 2 h in the range of 30-40 °C. The maximal enhancement was 75 %. Other abiotic stresses were also examined. Cold (0 °C) and partial anaerobiosis increased rhizome growth significantly. The increases brought about by drought and salinity were not statistically significant. Because underground storage tissues like rhizomes are adaptations to survive climatic stresses, we presume that the increased sink-strength of rhizomes induced by moderate stress is related to stress adaptation. Moderate heat stress (38 °C HWT, 1 h) also resulted in protection of Alstroemeria plantlets from severe heat stress (45 °C HWT, 1-2 h) a few hours after the moderate stress. All abiotic stresses also increased the outgrowth of lateral rhizomes. [ABSTRACT FROM AUTHOR]

Current generation using nitrite as substrate (pH 6.9, 40 mgN l) in a nitrite-fed microbial fuel cell was investigated under anaerobic and aerobic anodic conditions as an alternative to the biological nitrite oxidation process. Cell current, coulombic efficiency (CE) and power generation of 0.04 mA, 30 ± 2 % and 19.3 ± 3.3 μW m, respectively, were observed under anaerobic conditions while complete nitrite degradation (no current) was obtained under aerobic conditions. Switching from aerobic to anaerobic anode enhanced the CE and power generation (39 ± 1 % and 29 ± 4.3 μW m). [ABSTRACT FROM AUTHOR]

The concentrations of carotenoids buried in the bottom sediments of Lake Shira (Siberia, Khakassiya) have analyzed for the period of the last 2300 years. The bottom sediments were found to contain carotenoids, which are molecular markers of the corresponding groups of Phototrophic organisms. The bottom sediments of Lake Shira were shown to be a promising object for climate reconstructions of the Late Holocene in southern Siberia. [ABSTRACT FROM AUTHOR]

Combined effects of concentration of lactose (5 g/L), NaCl (20 g/L) and aero/anaerobiosis on production of tyramine by Enterococcus durans CCDM 53 were subjected to a study. The influence of the above factors and temperature of cultivation (10 ± 1 °C) was monitored under conditions applied in real technological processes of cheese production; the enterococci act as non-starter lactic acid bacteria. Production of tyramine by E. durans CCDM 53 was mainly influenced by both concentration of NaCl in cultivation medium and presence/absence of oxygen in the environment. The highest production of tyramine occurred during cultivation under anaerobic conditions in the presence of the highest (20 g/L) applied concentration of NaCl and lactose (5 g/L). In the media with equal concentrations of NaCl and lactose, the concentrations of tyramine grew higher under anaerobic conditions than in aerobic environment. Regarding cultivation media with various levels of NaCl and lactose, higher production of tyramine was always found in the anaerobic environment. [ABSTRACT FROM AUTHOR]

In this study we used tightly-coupled mitochondria from Yarrowia lipolytica and Dipodascus ( Endomyces) magnusii yeasts. The two yeast strains are good alternatives to Saccharomyces cerevisiae, being aerobes containing well-structured mitochondria (thus ensuring less structural limitation to observe their appreciable swelling) and fully competent respiratory chain with three invariantly functioning energy conservation points, including Complex I, that can be involved in induction of the canonical Ca/P-dependent mitochondrial permeability transition (mPTP pore) with an increased open probability when electron flux increases (Fontaine et al. J Biol Chem 273:25734-25740, ; Bernardi et al. FEBS J 273:2077-2099, ). High-amplitude swelling and collapse of the membrane potential were used as parameters for demonstrating pore opening. Previously (Kovaleva et al. J Bioenerg Biomembr 41:239-249, ; Kovaleva et al. Biochemistry (Moscow) 75:297-303, ) we have shown that mitochondria from Y. lipolytica and D. magnusii were very resistant to the Ca overload combined with varying concentrations of P, palmitic acid, SH-reagents, carboxyatractyloside (an inhibitor of ADP/ATP translocator), as well as depletion of intramitochondrial adenine nucleotide pools, deenergization of mitochondria, and shifting to acidic pH values in the presence of high [P]. Here we subjected yeast mitochondria to other conditions known to induce an mPTP in animal and plant mitochondria, namely to Ca overload under hypoxic conditions (anaerobiosis). We were unable to observe Ca-induced high permeability of the inner membrane of D. magnusii and Y. lipolytica yeast mitochondria under anaerobic conditions, thus suggesting that an mPTP-like pore, if it ever occurs in yeast mitochondria, is not coupled with the Ca uptake. The results provide the first demonstration of ATP-dependent energization of yeast mitochondria under conditions of anaerobiosis. [ABSTRACT FROM AUTHOR]

This paper is dedicated to the 35 year jubilee of the founding and the activity of the International Society for Plant Anaerobiosis (ISPA). The role of ISPA members in opening new avenues of research is emphasized. Major developments in the study of plant hypoxic and anoxic stress achieved during subsequent decades are considered. Special attention is given to plant adaptation and damage under conditions of oxygen deficiency and complete absence of oxygen as well as during the post-anaerobic period. Plant metabolic adaptation to anaerobic stress and the capacity of some plants to avoid anaerobiosis are discussed. [ABSTRACT FROM AUTHOR]

Modification of the phosphoenolpyruvate/sugar phosphotransferase system (PTS) has shown improvement in sugar coassimilation in Escherichia coli production strains. However, in preliminary experiments under anaerobic conditions, E. coli strains with an inactive PTS and carrying pLOI1594, which encodes pyruvate decarboxylase and alcohol dehydrogenase from Zymomonas mobilis, were unable to grow. These PTS strains were previously evolved under aerobic conditions to grow rapidly in glucose (PTS Glucose phenotype). Thus, in this work, applying a continuous culture strategy under anaerobic conditions, we generate a new set of evolved PTS Glucose mutants, VH30N1 to VH30N6. Contrary to aerobically evolved mutants, strains VH30N2 and VH30N4 carrying pLOI1594 grew in anaerobiosis; also, their growth capacity was restored in a 100%, showing specific growth rates ( μ ~ 0.12 h) similar to the PTS parental strain ( μ = 0.11 h). In cultures of VH30N2/pLOI1594 and VH30N4/pLOI1594 using a glucose-xylose mixture, xylose was totally consumed and consumption of sugars occurred in a simultaneous manner indicating that catabolic repression is alleviated in these strains. Also, the efficient sugar coassimilation by the evolved strains caused an increment in the ethanol yields. [ABSTRACT FROM AUTHOR]

Changes in the redox metabolism in the anaerobic, extremely thermophilic, hydrogen-forming bacterium Caldicellulosiruptor saccharolyticus were probed for the first time in vivo using mediated amperometry with ferricyanide as a thermotolerant external mediator. Clear differences in the intracellular electron flow were observed when cells were supplied with different carbon sources. A higher electrochemical response was detected when cells were supplied with xylose than with sucrose or glucose. Moreover, using the mediated electrochemical method, it was possible to detect differences in the electron flow between cells harvested in the exponential and stationary growth phases. The electron flow of C. saccharolyticus was dependent on the NADH- and reduced ferredoxin generation flux and the competitive behavior of cytosolic and membrane-associated oxidoreductases. Sodium oxamate was used to inhibit the NADH-dependent lactate dehydrogenase, upon which more NADH was directed to membrane-associated enzymes for ferricyanide reduction, leading to a higher electrochemical signal. The method is noninvasive and the results presented here demonstrate that this method can be used to accurately detect changes in the intracellular electron flow and to probe redox enzyme properties of a strictly anaerobic thermophile in vivo. [ABSTRACT FROM AUTHOR]

The earthworm gut provides ideal in situ conditions for ingested heterotrophic soil bacteria capable of anaerobiosis. High amounts of mucus- and plant-derived saccharides such as glucose are abundant in the earthworm alimentary canal, and high concentrations of molecular hydrogen (H2) and organic acids in the alimentary canal are indicative of ongoing fermentations. Thus, the central objective of this study was to resolve potential links between fermentations and active fermenters in gut content of the anecic earthworm Lumbricus terrestris by 16S ribosomal RNA (rRNA)-based stable isotope probing, with [13C]glucose as a model substrate. Glucose consumption in anoxic gut content microcosms was rapid and yielded soluble organic compounds (acetate, butyrate, formate, lactate, propionate, succinate and ethanol) and gases (carbon dioxide and H2), products indicative of diverse fermentations in the alimentary canal. Clostridiaceae and Enterobacteriaceae were users of glucose-derived carbon. On the basis of the detection of 16S rRNA, active phyla in gut contents included Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Cyanobacteria, Firmicutes, Gemmatimonadetes, Nitrospirae, Planctomycetes, Proteobacteria, Tenericutes and Verrucomicrobia, taxa common to soils. On the basis of a 16S rRNA gene similarity cutoff of 87.5%, 82 families were detected, 17 of which were novel family-level groups. These findings (a) show the large diversity of soil taxa that might be active during gut passage, (b) show that Clostridiaceae and Enterobacteriaceae (fermentative subsets of these taxa) are selectively stimulated by glucose and might therefore be capable of consuming mucus- and plant-derived saccharides during gut passage and (c) indicate that ingested obligate anaerobes and facultative aerobes from soil can concomitantly metabolize the same source of carbon. [ABSTRACT FROM AUTHOR]

The article focuses on the metabolic capabilities of two eurytopic organisms geomyces pannorum strains under different anaerobiosis conditions. It states that geomyces fungi are organisms with wide species distribution area that has the aptitude to grow and figure the fermentation products that were associated by increase of lactate and acetate. It mentions that the strain that was secluded from cryopeg water and from the hair of bank vole cletrionomys glareolus were the objects of the study.

The article presents a study which seeks to confirm the assumption that Fnr[4Fe-4S] 2+, an Escherichia coli's universal anaerobiosis protein, acts as a regulator of aidB expression and an NO sensor during anaerobic growth. It says that the study used the E. coli strain MV2176 containing the [aidB1::lacZ] construct in the chromosome. The result shows that Fnr[4Fe4S] 2+ protein regulates the aidB gene's expression of the Ada regulon under anaerobic conditions.

During a general survey of the acetaldehyde-producing properties of commercially available wine yeast strains, we discovered that, although final acetaldehyde production cannot be used as a discriminating factor between yeast strains, initial specific acetaldehyde production rates were of highly interest for classifying yeast strains. This parameter is very closely related to the growth- and fermentation-lag phase durations. We also found that this acetaldehyde early production occurs with very different extent between commercial active dry yeast strains during the rehydration phase and could partially explain the known variable resistance of yeast strains to sulfites. Acetaldehyde production appeared, therefore, as very precocious, strain-dependent, and biomass-independent character. These various findings suggest that this new intrinsic characteristic of industrial fermenting yeast may be likely considered as an early marker of the general fermenting activity of industrial fermenting yeasts. This phenomenon could be particularly important for understanding the ecology of colonization of complex fermentation media by Saccharomyces cerevisiae. [ABSTRACT FROM AUTHOR]

Anaerobic metabolism is controlled by several transcriptional regulators, including ArcA, Fnr, NarP, and NarL, with the Fnr and ArcA proteins sensitive to the cell's redox status. Specifically, the two-component ArcAB system is activated in response to the oxidation state of membrane-bound quinones, which are the central electron carriers of respiration. Fnr, by contrast, directly senses cellular oxidation status through the [4Fe-4S] cluster present in its own structure. In this study, a third additional redox-associated pathway that controls the nitrate respiration regulators NarL and NarP was identified. The results showed that, in Salmonella enterica, the expression of these two transcriptional regulators is under the control of Fur, a metalloregulator that senses the presence of Fe2+ and regulates the homeostasis of this cation inside the cell. Thus, the Fur-Fe2+ complex increases the expression of narL and represses that of narP. Furthermore, studies of S. enteric mutants defective in the Fur-regulated sRNA RfrA and RfrB showed that those sRNA control both narP and narL expression. These results confirm Fur as a global regulator based on its involvement not only in iron uptake and detoxification but also in the control of nitrate/nitrite respiration by sensing cellular redox status. [ABSTRACT FROM AUTHOR]

Several species of unicellular green algae, such as the model green microalga Chlamydomonas reinhardtii, can operate under either aerobic photosynthesis or anaerobic metabolism conditions. A particularly interesting metabolic condition is that of ‘‘anaerobic oxygenic photosynthesis’’, whereby photosynthetically generated oxygen is consumed by the cell’s own respiration, causing anaerobiosis in the culture in the light, and induction of the cellular ‘‘hydrogen metabolism’’ process. The latter entails an alternative photosynthetic electron transport pathway, through the oxygensensitive FeFe-hydrogenase, leading to the light-dependent generation of molecular hydrogen in the chloroplast. The FeFe-hydrogenase is coupled to the reducing site of photosystem-I via ferredoxin and is employed as an electronpressure valve, through which electrons are dissipated, thus permitting a sustained electron transport in the thylakoid membrane of photosynthesis. This hydrogen gas generating process in the cells offers testimony to the unique photosynthetic metabolism that can be found in many species of green microalgae. Moreover, it has attracted interest by the biotechnology and bioenergy sectors, as it promises utilization of green microalgae and the process of photosynthesis in renewable energy production. This article provides an overview of the principles of photobiological hydrogen production in microalgae and addresses in detail the process of induction and analysis of the hydrogen metabolism in the cells. Furthermore, methods are discussed by which the interaction of photosynthesis, respiration, cellular metabolism, and H2 production in Chlamydomonas can be monitored and regulated. [ABSTRACT FROM AUTHOR]

Ducks are well-known to be more tolerant to asphyxia than non-diving birds, but it is not known if their defences include enhanced neuronal hypoxia tolerance. To test this, we compared extracellular recordings of spontaneous activity in the Purkinje cell layer of 400 μm thick isolated cerebellar slices from eider ducks, chickens and rats, before, during and after 60 min hypoxia (95%N2–5%CO2) or chemical anoxia (hypoxia + 2 mM NaCN). Most slices rapidly lost activity in hypoxia, with or without recovery after rinse and return to normoxia (95%O2–5%CO2), but some maintained spontaneous activity throughout the insult. Proportions of ‘surviving’ (i.e. recovering or active) duck slices were significantly higher than for chickens in anoxia, and relative activity levels were higher for ducks than for chickens during hypoxia, anoxia and recovery. Survival of rat slices was significantly poorer than for birds under all conditions. Results suggest that (1) duck cerebellar neurons are intrinsically more hypoxia-tolerant than chicken neurons; (2) avian neurons are more hypoxia-tolerant than rat neurons, and (3) the enhanced hypoxic tolerance of duck neurons largely depended on efficient anaerobiosis since it mainly manifested itself in chemical anoxia. Mechanisms underlying the observed differences in neuronal hypoxic responses remain to be elucidated. [ABSTRACT FROM AUTHOR]

Though the affinity of iron oxides and hydroxides for phosphorus (P) is thought to limit growth and productivity of plants on iron-rich acidic soils in humid tropical climate, tall trees are found in tropical rainforests, and vigorous growth occurs in herbaceous vegetation in the humid tropical climate of the Andamans. Our study reports how high rainfall influences Bray and Kurtz P-1 extractable P, water filled pore space (WFPS), microbial biomass carbon (MB-C) and phosphorus (MB-P) in the gravelly-sandy-loamy soils in three major land use systems: moist-evergreen forest, semi-evergreen forest and homegarden, in the equatorial humid tropical climate of South Andaman island of India. In addition, an ex-situ experiment investigated how labile carbon (glucose) under different soil-water regimes [25% field capacity (FC) and 100% FC] affected the P in the soils under the land use systems. WFPS, across the land use systems, was more than two times higher during the high rainfall than dry spell (72–80 hr after the high rainfall). The extractable P, across the land use systems, increased about 5 to 6 fold during the high rainfall than dry spell. The increase was the highest in the homegarden and lowest in moist-evergreen forest. The extractable P was positively correlated with the WFPS. MB-C and MB-P were lower during the high rainfall than dry spell in all the land use systems. In the ex-situ experiment, the extractable P increased 1.4 to 1.7 fold more in water (100% FC) + glucose than water (100% FC) alone treatment. Water at 25% FC did not increase the extractable P in the soils under all the land use systems. After cessation of the high rainfall, WFPS declined quickly within 2-hr in the upper layer (0–5 cm) of the soils. These indicate that the high rainfall together with labile carbon increases the extractable P through anaerobiosis, whereas, quick decline in the WFPS (0–5 cm) following cessation of the high rainfall helps its uptake by plants and microflora. [ABSTRACT FROM AUTHOR]

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In Escherichia coli, Lon is an ATP-dependent protease which degrades misfolded proteins and certain rapidly-degraded regulatory proteins. Given that oxidatively damaged proteins are generally degraded rather than repaired, we anticipated that Lon deficient cells would exhibit decreased viability during aerobic, but not anaerobic, carbon starvation. We found that the opposite actually occurs. Wild-type and Lon deficient cells survived equally well under aerobic conditions, but Lon deficient cells died more rapidly than the wild-type under anaerobiosis. Aerobic induction of the Clp family of ATP-dependent proteases could explain these results, but direct quantitation of Clp protein established that its level was not affected by Lon deficiency and overexpression of Clp did not rescue the cells under anaerobic conditions. We conclude that the Lon protease supports survival during anaerobic carbon starvation by a mechanism which does not depend on Clp. [ABSTRACT FROM AUTHOR]