Sulfite-reducing Bacteria Research Articles

Level of Contamination and Alteration of Cuttlefish Fished and Processed in Companies in Côte d’Ivoire

This study was carried out from 2019 to 2021. Its aim was to assess the quality of cuttlefish intended for local and international markets in a company processing fishery products in Côte d'Ivoire. The biochemical analyses (Total Volatile Basic Nitrogen (TVBN)) were based on the distillation method of an extract deproteinised by perchloric acid (HClO<sub>4</sub>). Microbiological analyses (total aerobic mesophilic flora (TAMF), staphylococci (SPP), anaerobic sulphite-reducing bacteria (RAS), faecal coliforms (FC) and salmonella) involved isolation and identification techniques. The various analyses carried out by the National Laboratory for Support to Agricultural Development (LANADA) made it possible to assess the median contamination values and satisfaction percentages (TAMF, FC, SPP), which are respectively 2.2.10<sup>4</sup> CFU/g with 94%; less than 10 CFU/g with 94%; less than 100 CFU/g with 100%. RSA and salmonella were absent in all the products analysed. The temperature of the cuttlefish was high just after processing. The maximum temperature value (26.4°C) was obtained after processing, while the minimum temperature value (1.6°C) was recorded during storage in a positive cold room. However, it is essential to improve manufacturing practices and preservation methods in order to avoid poisoning the population. These data should also encourage fishermen to practise good preservation methods.

Quality of Propolis Commercially Available on Podkarpacki Beekeeping Market

Abstract Eight samples of propolis commercially available on south-eastern Poland’s beekeeping market were compared in terms of quality, chemical composition and biological activity, including antioxidant and antimicrobial properties. The organoleptic characteristics and physicochemical requirements indicated that only 50% of tested propolis samples was classified to class II regarding obligatory limits, while the others were out-class. A big variation in mineral composition was determined by the ICP-OES method but all samples were free of heavy metals (Pb, Cd and Ni). Although mesophilic bacteria, yeasts and moulds occurred in tested propolis (in general lower than 102 CFU/g), E. coli and spore-forming sulphite-reducing bacteria as well as Salmonella and Shigella bacteria were not detected. High antioxidant activity and total phenolic content for all samples was confirmed, which was correlated with antibacterial activity tested against E. coli ATCC 11775 strain. Additionally, the propolis sample with the strongest antibacterial activity (MIC 0.33 mg/mL) inhibited biofilm formation of S. aureus and S. epidermidis ATCC 35984 (MBIC 0.66 and 5.25 mg/mL, respectively). However, great variation in terms of antioxidant activity and HPLC polyphenolic profile were observed, and sakuranetin and pinobanksin were identified as the most effective antioxidant components. Moreover, the usefulness of ATR-FTIR spectra analysis was confirmed as a quick method for initial testing of propolis quality.

Bacterial cysteate dissimilatory pathway involves a racemase and d-cysteate sulfo-lyase

The sulfite-reducing bacterium Bilophila wadsworthia, a common human intestinal pathobiont, is unique in its ability to metabolize a wide variety of sulfonates to generate sulfite as a terminal electron acceptor (TEA). The resulting formation of H2S is implicated in inflammation and colon cancer. l-cysteate, an oxidation product of l-cysteine, is among the sulfonates metabolized by B. wadsworthia, although the enzymes involved remain unknown. Here we report a pathway for l-cysteate dissimilation in B. wadsworthia RZATAU, involving isomerization of l-cysteate to d-cysteate by a cysteate racemase (BwCuyB), followed by cleavage into pyruvate, ammonia and sulfite by a d-cysteate sulfo-lyase (BwCuyA). The strong selectivity of BwCuyA for d-cysteate over l-cysteate was rationalized by protein structural modeling. A homolog of BwCuyA in the marine bacterium Silicibacter pomeroyi (SpCuyA) was previously reported to be a l-cysteate sulfo-lyase, but our experiments confirm that SpCuyA too displays a strong selectivity for d-cysteate. Growth of B. wadsworthia with cysteate as the electron acceptor is accompanied by production of H2S and induction of BwCuyA. Close homologs of BwCuyA and BwCuyB are present in diverse bacteria, including many sulfate- and sulfite-reducing bacteria, suggesting their involvement in cysteate degradation in different biological environments.

Comparison of microbial communities and the profile of sulfate-reducing bacteria in patients with ulcerative colitis and their association with bowel diseases: a pilot study.

Considerable evidence has accumulated regarding the molecular relationship between gut microbiota (GM) composition and the onset (clinical presentation and prognosis of ulcerative colitis (UC)). In addition, it is well documented that short-chain fatty acid (SCFA)-producing bacteria may play a fundamental role in maintaining an anti-inflammatory intestinal homeostasis, but sulfate- and sulfite reducing bacteria may be responsible for the production of toxic metabolites, such as hydrogen sulfide and acetate. Hence, the present study aimed to assess the GM composition - focusing on sulfate-reducing bacteria (SRB) - in patients with severe, severe-active and moderate UC. Each one of the six enrolled patients provided two stool samples in the following way: one sample was cultivated in a modified SRB-medium before 16S rRNA sequencing and the other was not cultivated. Comparative phylogenetic analysis was conducted on each sample. Percentage of detected gut microbial genera showed considerable variation based on the patients' disease severity and cultivation in the SRB medium. In detail, samples without cultivation from patients with moderate UC showed a high abundance of the genera Bacteroides, Bifidobacterium and Ruminococcus, but after SRB cultivation, the dominant genera were Bacteroides, Klebsiella and Bilophila. On the other hand, before SRB cultivation, the main represented genera in patients with severe UC were Escherichia-Shigella, Proteus, Methanothermobacter and Methanobacterium. However, after incubation in the SRB medium Bacteroides, Proteus, Alistipes and Lachnoclostridium were predominant. Information regarding GM compositional changes in UC patients may aid the development of novel therapeutic strategies (e.g., probiotic preparations containing specific bacterial strains) to counteract the mechanisms of virulence of harmful bacteria and the subsequent inflammatory response that is closely related to the pathogenesis of inflammatory bowel diseases.

A Variant of the Sulfoglycolytic Transketolase Pathway for the Degradation of Sulfoquinovose into Sulfoacetate.

Sulfoquinovose (SQ, 6-deoxy-6-sulfo-glucose) constitutes the polar head group of plant sulfolipids and is one of the most abundantly produced organosulfur compounds in nature. Degradation of SQ by bacterial communities contributes to sulfur recycling in many environments. Bacteria have evolved at least four mechanisms for glycolytic degradation of SQ, termed sulfoglycolysis, producing C3 sulfonate (dihydroxypropanesulfonate and sulfolactate) and C2 sulfonate (isethionate) by-products. These sulfonates are further degraded by other bacteria, leading to the mineralization of the sulfonate sulfur. The C2 sulfonate sulfoacetate is widespread in the environment and is also thought to be a product of sulfoglycolysis, although the mechanistic details are yet unknown. Here, we describe a gene cluster in an Acholeplasma sp., from a metagenome derived from deeply circulating subsurface aquifer fluids (GenBank accession no. QZKD01000037), encoding a variant of the recently discovered sulfoglycolytic transketolase (sulfo-TK) pathway that produces sulfoacetate instead of isethionate as a by-product. We report the biochemical characterization of a coenzyme A (CoA)-acylating sulfoacetaldehyde dehydrogenase (SqwD) and an ADP-forming sulfoacetate-CoA ligase (SqwKL), which collectively catalyze the oxidation of the transketolase product sulfoacetaldehyde into sulfoacetate, coupled with ATP formation. A bioinformatics study revealed the presence of this sulfo-TK variant in phylogenetically diverse bacteria, adding to the variety of mechanisms by which bacteria metabolize this ubiquitous sulfo-sugar. IMPORTANCE Many bacteria utilize environmentally widespread C2 sulfonate sulfoacetate as a sulfur source, and the disease-linked human gut sulfate- and sulfite-reducing bacteria can use it as a terminal electron receptor for anaerobic respiration generating toxic H2S. However, the mechanism of sulfoacetate formation is unknown, although it has been proposed that sulfoacetate originates from bacterial degradation of sulfoquinovose (SQ), the polar head group of sulfolipids present in all green plants. Here, we describe a variant of the recently discovered sulfoglycolytic transketolase (sulfo-TK) pathway. Unlike the regular sulfo-TK pathway that produces isethionate, our biochemical assays with recombinant proteins demonstrated that a CoA-acylating sulfoacetaldehyde dehydrogenase (SqwD) and an ADP-forming sulfoacetate-CoA ligase (SqwKL) in this variant pathway collectively catalyze the oxidation of the transketolase product sulfoacetaldehyde into sulfoacetate, coupled with ATP formation. A bioinformatics study revealed the presence of this sulfo-TK variant in phylogenetically diverse bacteria and interpreted the widespread existence of sulfoacetate.

A (S)-3-Hydroxybutyrate Dehydrogenase Belonging to the 3-Hydroxyacyl-CoA Dehydrogenase Family Facilitates Hydroxyacid Degradation in Anaerobic Bacteria.

Ketone bodies, including acetoacetate, 3-hydroxybutyrate, and acetone, are produced in the liver of animals during glucose starvation. Enzymes for the metabolism of (R)-3-hydroxybutyrate have been extensively studied, but little is known about the metabolism of its enantiomer (S)-3-hydroxybutyrate. Here, we report the characterization of a novel pathway for the degradation of (S)-3-hydroxybutyrate in anaerobic bacteria. We identify and characterize a stereospecific (S)-3-hydroxylbutyrate dehydrogenase (3SHBDH) from Desulfotomaculum ruminis, which catalyzes the reversible NAD(P)H-dependent reduction of acetoacetate to form (S)-3-hydroxybutyrate. 3SHBDH also catalyzes oxidation of d-threonine (2R, 3S) and l-allo-threonine (2S, 3S), consistent with its specificity for β-(3S)-hydroxy acids. Isothermal calorimetry experiments support a sequential mechanism involving binding of NADH prior to (S)-3-hydroxybutyrate. Homologs of 3SHBDH are present in anaerobic fermenting and sulfite-reducing bacteria, and experiments with Clostridium pasteurianum showed that 3SHBDH, acetate CoA-transferase (YdiF), and (S)-3-hydroxybutyryl-CoA dehydrogenase (Hbd) are involved together in the degradation of (S)-3-hydroxybutyrate as a carbon and energy source for growth. (S)-3-hydroxybutyrate is a human metabolic marker and a chiral precursor for chemical synthesis, suggesting potential applications of 3SHBDH in diagnostics or the chemicals industry. IMPORTANCE (R)-3-hydroxybutyrate is well studied as a component of ketone bodies produced by the liver and of bacterial polyesters. However, the biochemistry of its enantiomer (S)-3-hydroxybutyrate is poorly understood. This study describes the identification and characterization of a stereospecific (S)-3-hydroxylbutyrate dehydrogenase and its function in a metabolic pathway for the degradation of (S)-3-hydroxybutyrate as a carbon and energy source in anaerobic bacteria. (S)-3-hydroxybutyrate is a mammalian metabolic marker and a precursor for chemical synthesis and bioplastics, suggesting potential applications of these enzymes in diagnostics and biotechnology.

Carbon sequestration from refractory dissolved organic carbon produced by biodegradation of Saccharina japonica

Using macroalgae cultures to sequester carbon has been proposed in recent years. Yet the key mechanism of carbon sequestration—how carbon in degrading biomass is converted into refractory dissolved organic carbon (RDOC) remains poorly understood. The process of producting RDOC via biomass degradation of Saccharina japonica, the most productive algae in China, was thus studied in the laboratory. Most of the carbon in the kelp biomass was converted to dissolved inorganic carbon (DIC) by bacterial respiration. Only 7.8% of the carbon in the kelp biomass was converted into labile DOC, semi-labile or semi-refractory DOC, and refractory DOC in turn. The enrichment of DIC resulted in hypoxic conditions in the water. For the hypoxia in the experiment, the sulfur-degrading bacteria Campylobacteria and Bacteroidia became the dominant bacterial classes, which were the key drivers for the transformation of labile DOC to semi-labile or semi-refractory DOC. Then, semi-labile or semi-refractory DOC was converted to RDOC, driven by the sulfite-reducing bacteria Clostridia and Kapabacteria. Finally, 0.3% of the carbon content in kelp was transformed into RDOC. The resulting RDOC, which was rich in sulfur and nitrogen elements, increased the molecular diversity and average molecular weight in the water. An important finding was that the production of RDOC may be accompanied by the environmental risk of hypoxia.

Physico-chemical, microbial and toxicity assessment of industrial effluents from the southern Tunisian tannery

The management of tanning effluents is a real problem for leather-producing countries. Therefore, the treatment solution search for this potentially toxic industrial wastewater constitutes a priority. In this study, the physico-chemical, microbiological, and spectral characterizations as well as micro-toxicity study, of these effluents, were carried out. The physico-chemical analyses showed the complex nature of such untreated effluent. In fact, its composition revealed a high biochemical oxygen demand (BOD5 = 3100 ± 100 mg/L), chemical oxygen demand (COD = 14,065.2 ± 155 mg/L), total suspended solids (TSS = 12.30 ± 2.64 mg/L), total dissolved solution (TDS = 44.2 ± 3.46 mg/L), sulphate (2076.068 ± 50.27 mg/L), chromium (4.525 ± 0.23 mg/L), sodium (22,800 ± 80.16 mg/L), and lead (0.739 ± 0.04 mg/L) content with alkaline pH (12.93) and greenish-blue color. Moreover, the spectral analyses (UV-vis and FT-IR) of the basin 1, 2 and 3 effluents show its complexity, before treatment, which justifies the physico-chemical characterization. The final effluent (basin 5), after biological treatment, was characterized and a decrease was noticed in all cited parameters. In addition, the ratio COD/BOD5 was decreased 3.3 folds. The microbiological characterization revealed the presence of revivable aerobic bacteria as; total coliforms, fecal coliforms, Pseudomonas, Enterococcus (streptococci D), sulphite-reducing bacteria, and fungi. In contrast, a complete absence of Salmonella, Yersinia enterocolitica, Vibrio cholerae, and Helminth egg was noted. To confirm the efficiency of the biological treatment via an adapted consortium, micro-toxicity tests using Escherichia coli and Bacillus subtilis were carried out. Results of this monitoring showed an important decrease in the toxicity levels for the final effluent.

Copper oxide/peroxydisulfate system for urban wastewater disinfection: Performances, reactive species, and antibiotic resistance genes removal

In this study, copper oxide (CuO) catalyzed peroxydisulfate (PDS) system was investigated for the inactivation of a broad range of pathogenic microorganisms from urban wastewater. Complete inactivation of Escherichia coli, Enterococcus, F-specific RNA bacteriophages from secondary treated wastewater was achieved after a short time (15–30 min) treatment with CuO (10 g/L)/PDS (1 mM) system, but spores of sulfite-reducing bacteria took 120 min. No bacterial regrowth occurred during storage after treatment. Significant reduction of the pathogens was explained by the generation of the highly selective Cu(III) oxidant, as the predominant reactive species, which could quickly oxidize guanine through a one-electron oxidation pathway. Additionally, the potential of the CuO (10 g/L)/PDS (1 mM) system to inactivate antibiotic-resistant bacteria and antibiotic resistance genes (ARB&Gs) was explored. Sulfamethoxazole-resistant E. coli was used as the model ARB and a 3.2 log of reduction was observed after 10 min of treatment. A considerable reduction (0.7–2.3 log) of selected ARGs including blaTEM, qnrS, emrB, sul1, and genes related to the dissemination of antibiotic resistance, including the Class 1 integron-integrase (intI1), and the insertion sequence (IS613) was achieved after 60 min treatment. All these findings indicated the promising applicability of the CuO/PDS system as a disinfection technology for wastewater reuse in agriculture.

Microbial content of non-fermented liquid feed consumed by sows affects the occurrence of neonatal diarrhoea in their piglets: A case-control study.

Microbial colonisation of piglets' intestines starts at birth, especially from contact with sow's faeces. Piglet microbiota could therefore be influenced by the sow's diet. The objective of this study was to evaluate whether the microbiological flora of liquid feed for sows can be associated with the development of neonatal diarrhoea. This study was carried out on 10 case farms with neonatal diarrhoea and 10 control farms without neonatal diarrhoea. On each farm, a microbiological analysis of gestating and lactating liquid feed was performed. A generalised linear model was used to study the impact of the liquid feed microbiological counts and pH on the probability of neonatal diarrhoea developing. For thermotolerant coliforms, sulphite-reducing bacteria, heterotrophic bacteria and lactic-acid bacteria counts, there was no significant difference between case and control farms. The higher the count of total coliforms, enterococci and yeasts in sow non-fermented liquid feed, the greater the probability of observing neonatal diarrhoea. Moreover, taking into account total coliforms and yeasts counts together is highly predictive of neonatal diarrhoea risk. This study offers new perspectives of investigation and understanding of neonatal diarrhoea in breeding farms feeding sows with a non-fermented liquid feed.

Glycyl Radical Enzymes and Sulfonate Metabolism in the Microbiome.

Sulfonates include diverse natural products and anthropogenic chemicals and are widespread in the environment. Many bacteria can degrade sulfonates and obtain sulfur, carbon, and energy for growth, playing important roles in the biogeochemical sulfur cycle. Cleavage of the inert sulfonate C-S bond involves a variety of enzymes, cofactors, and oxygen-dependent and oxygen-independent catalytic mechanisms. Sulfonate degradation by strictly anaerobic bacteria was recently found to involve C-S bond cleavage through O2-sensitive free radical chemistry, catalyzed by glycyl radical enzymes (GREs). The associated discoveries of new enzymes and metabolic pathways for sulfonate metabolism in diverse anaerobic bacteria have enriched our understanding of sulfonate chemistry in the anaerobic biosphere. An anaerobic environment of particular interest is the human gut microbiome, where sulfonate degradation by sulfate- and sulfite-reducing bacteria (SSRB) produces H2S, a process linked to certain chronic diseases and conditions.

What removals of pathogen indicators can be expected within large-scale wastewater treatment facilities in the context of wastewater reuse in Paris conurbation?

The fate of pathogen indicators (Escherichia coli - EC, intestinal enterococci - IE, RNA-F bacteriophages and spores of sulfite reducing bacteria - SSR) was extensively studied in Parisian large-scale wastewater treatment plants (WWTPs), based on conventional activated sludge, biofiltration or membrane bioreactor (MBR) processes. Between 14 and 87 campaigns were performed between 2014 and 2018 in five WWTPs. High removals of 3 log for both EC and IE, and lower removals of 1-2 log for SSR and RNA-F bacteriophages, were observed in conventional activated sludge and biofiltration WWTPs. The MBR WWTP achieves notably greater removals of 4.5-5.5 log for faecal bacteria and 3-4 log for SSR and RNA-F bacteriophages. This WWTP is the only one already in compliance with reuse standards, the other ones being non-compliant because of SSR and RNA-F bacteriophages. The implementation of a micro-grain activated carbon process would increase the WWTP removals of 0.8 log for faecal bacteria, due to particles retention, with no significant effect on both other pathogens. Ozonation (0.9-1.3 g O3/g dissolved organic carbon) or performic acid (0.8-1.2 ppm) would have greater benefits with additional removals of 1.5-2.5 log for EC, 1-2 log for IE and 0.5-1 log for SSR and RNA-F bacteriophages. Correlations between pathogen indicator removals and initial concentrations were found, as well as a significant decrease of RNA-F bacteriophage concentrations in Parisian raw wastewater, below 2 log. Thus, RNA-F bacteriophages could be a real issue to evaluate the compliance of Parisian wastewater with reuse. The time evolution of removals demonstrated that SSR is the most problematic parameter regarding reuse in conventional activated sludge and biofiltration WWTPs, as its initial concentration is high (5 log) but removals insufficient (<2 log). In contrast, removals of RNA-F bacteriophages greater than 2 log can be obtained within WWTPs completed or not with a tertiary treatment when the initial concentration in raw wastewater is sufficient. Correlations were also found between the removals of pathogen indicators and the removals of physico-chemical parameters, but they are not good enough to allow performance predictions.

Bacteriological Quality of a Forage Grass (&amp;lt;i&amp;gt;Pennisetum purpureum Schumach&amp;lt;/i&amp;gt;) Used in Constructed Wetland Removing Domestic Wastewater Pathogenic Microorganism

Constructed Wetlands (CWs) are an adequate wastewater treatment system with possibility to generate income, in particular by the use of plants of economic interest. However, very few studies deal with the bacteriological quality of plants after wastewater treatment. Thermotolerant coliforms and Sulfite-reducing bacteria were investigated on the above-ground biomass of a species of forage plant (Pennisetum purpureum) as well as their removal in an experimental pilot consisting of four beds, for three months. Two beds were planted and two unplanted beds were used as control. Germs in the wastewater were significantly reduced in both filtrates, with higher removal efficiency of 97.4% for Thermotolerant coliforms and 87.5% for Sulfite-reducing bacteria, in the planted bed. Wastewater treatment resulted in bacteriological contamination of the above-ground plant biomass with a significant decreases in number of germs from 660 to 28 CFU/g (Thermotolerant coliforms) and from 15 to 0 CFU/g (Sulfite-reducing bacteria), when the harvest height increased from the base to the upper end of the plants. However, averages of 305 CFU/g of Thermotolerant coliforms and 5 CFU/g of Sulfite-reducing bacteria were obtained in the above-ground plant biomass which would not present any potential risks for a possible use of the plant biomass as fodder. Thus, the use of forage plant suggests good prospects for upgrading said plants for animal feed.

Microbiological quality and safety of commercialized thalassotherapy products based on marine mud and algae extracts in Tunisia.

A total of 15 samples of thalassotherapy products, distributed in Tunisia in their intact and final state of production, was analyzed to determine their microbiological safety status. The result shows the absence of pathogenic bacteria (Staphylococcus aureus, Candida albicans, Salmonella, Pseudomonas aeruginosa and coliforms). The incidence of contamination by Gram-positive Bacilli (mesophelic bacteria, aerobic and anaerobic spore forming bacteria, anaerobic sulphite-reducing bacteria) was found to be higher in products composed by mud and extract of alga. The biochemical and molecular identification of the major contaminant show that Bacilli were the most covered from 75% of the thalassotherapy products. Mineral analysis (organic matter, Fe, Mg, Ca, Na d K, Al, Si and Ti) shows strong composition on Aluminum and Silica. Cytotoxicity study of six thalassotherapy products and three essential oil extracts (Menthol, Clove and Eucalyptus) did not show any cytotoxic effect. Furthermore, antibacterial acitivity of 5 essentila oils, against 30 isolates of the genus Bacillus and 10 reference strains, has been characterized showing an interesting bactericidal potential of the extract of menthol and Eucalyptus.

Two radical-dependent mechanisms for anaerobic degradation of the globally abundant organosulfur compound dihydroxypropanesulfonate

2(S)-dihydroxypropanesulfonate (DHPS) is a microbial degradation product of 6-deoxy-6-sulfo-d-glucopyranose (sulfoquinovose), a component of plant sulfolipid with an estimated annual production of 1010 tons. DHPS is also at millimolar levels in highly abundant marine phytoplankton. Its degradation and sulfur recycling by microbes, thus, play important roles in the biogeochemical sulfur cycle. However, DHPS degradative pathways in the anaerobic biosphere are not well understood. Here, we report the discovery and characterization of two O2-sensitive glycyl radical enzymes that use distinct mechanisms for DHPS degradation. DHPS-sulfolyase (HpsG) in sulfate- and sulfite-reducing bacteria catalyzes C-S cleavage to release sulfite for use as a terminal electron acceptor in respiration, producing H2S. DHPS-dehydratase (HpfG), in fermenting bacteria, catalyzes C-O cleavage to generate 3-sulfopropionaldehyde, subsequently reduced by the NADH-dependent sulfopropionaldehyde reductase (HpfD). Both enzymes are present in bacteria from diverse environments including human gut, suggesting the contribution of enzymatic radical chemistry to sulfur flux in various anaerobic niches.

Metabolic potentials of archaeal lineages resolved from metagenomes of deep Costa Rica sediments.

Numerous archaeal lineages are known to inhabit marine subsurface sediments, although their distributions, metabolic capacities, and interspecies interactions are still not well understood. Abundant and diverse archaea were recently reported in Costa Rica (CR) margin subseafloor sediments recovered during IODP Expedition 334. Here, we recover metagenome-assembled genomes (MAGs) of archaea from the CR margin and compare them to their relatives from shallower settings. We describe 31 MAGs of six different archaeal lineages (Lokiarchaeota, Thorarchaeota, Heimdallarchaeota, Bathyarcheota, Thermoplasmatales, and Hadesarchaea) and thoroughly analyze representative MAGs from the phyla Lokiarchaeota and Bathyarchaeota. Our analysis suggests the potential capability of Lokiarchaeota members to anaerobically degrade aliphatic and aromatic hydrocarbons. We show it is genetically possible and energetically feasible for Lokiarchaeota to degrade benzoate if they associate with organisms using nitrate, nitrite, and sulfite as electron acceptors, which suggests a possibility of syntrophic relationships between Lokiarchaeota and nitrite and sulfite reducing bacteria. The novel Bathyarchaeota lineage possesses an incomplete methanogenesis pathway lacking the methyl coenzyme M reductase complex and encodes a noncanonical acetogenic pathway potentially coupling methylotrophy to acetogenesis via the methyl branch of Wood-Ljungdahl pathway. These metabolic characteristics suggest the potential of this Bathyarchaeota lineage to be a transition between methanogenic and acetogenic Bathyarchaeota lineages. This work expands our knowledge about the metabolic functional repertoire of marine benthic archaea.

Water and health risk assessment in the Aracaju Expansion Zone - SE

Abstract The Aracaju Expansion Zone presents problems related to lack of water in adequate conditions of quantity and quality. The low purchasing power of the local community has led residents to excavate shallow wells in their homes to ensure water supply, the only alternative for domestic consumption, but untreated. The objective of this work was to evaluate the quality of well water and the scenarios of health risk, through microbiological analyses. The collections were carried out in the period from December 2015 to August 2017, according to the methodology established by Standard Methods for the Examination of Water and Wastewater, 21st ed. It was concluded that in the rainy season, the well water presents contamination by coliforms, heterotrophic bacteria, Staphylococcus aureos and sulfite reducing bacteria, while in the dry season most of the samples did not present bacteriological counts

The effect of citric acid on the physicochemical and microbiological parameters of processed burger meat

Meat can undergo many changes and harbor a large number of pathogenic and spoilage microorganisms during primary and further processing. The objective of this research was to study the effect of citric acid on the physicochemical and microbiological parameters of burger meat. This study was conducted in ten different processed meat factories in Lebanon during August 2018. The different samples of meat were marinated using Citric Acid (CA), with two concentrations of 1.5% (CA1.5) and 3% (CA3), untreated meat is used as a control (CA0). The burger minced meat samples were collected at four specific processing stages: grinding, spice addition, fine grinding, and molding, and then spray washed separately with citric acid. The samples were analyzed for their physicochemical properties such as pH, humidity, weight loss, meat protein. Microbiological analysis was also conducted on the meat samples (Total viable count, Escherichia coli, Staphylococcus aureus, Sulfite Reducing bacteria and Salmonella). Results showed that 3% of citric acid concentration resulted in the greatest reduction in cooking loss and pH, with a greater increase in the moisture content of the burger meat and had no effect on the meat protein content. Moreover, the citric acid concentration at 3% resulted in the highest reduction of bacteria population on meat burgers. It was concluded that citric acid is highly effective in decontaminating meat burgers and in preserving its physicochemical properties and can be useful during the stages of processing especially at the spice addition stage.

Seasonal bacterial community dynamics in a crude oil refinery wastewater treatment plant.

The biological treatment of oil refinery effluents in wastewater treatment plants (WWTPs) relies on specialized bacteria contributing to remove organic load, nitrogen, sulfur, and phosphorus compounds. Knowledge about bacterial dynamics in WWTPs and how they affect the performance of the wastewater treatment is limited, particularly in tropical countries. The bacterial communities from three compartments of an oil refinery WWTP in Uran, India, were assessed using 16S-metabarcoding, in winter and monsoon seasons, upstream (from the surge pond) and downstream the biotower (clarifier and guard pond), to understand the effects of seasonal variations in WWTP's efficiency. The organic load and ammonia levels of the treated wastewater increased by 3- and 9-fold in the monsoon time-point. A decreased abundance and diversity of 47 genera (325 OTUs) comprising ammonia and nitrite oxidizing bacteria (AOB, NOB, denitrifiers) was observed in the monsoon season downstream the biotower, whereas 23 OTUs of Sulfurospirillum, Desulfovibrio, and Bacillus, putatively performing dissimilatory nitrate reduction to ammonia (DNRA), were 3-fold more abundant in the same compartments (DNRA/denitrifiers winter ratio < 0.5 vs. monsoon ratio around 3). The total abundance of reported sulfate- and sulfite-reducing bacteria also increased 250- and 500-fold downstream the biotower, in the monsoon time-point. Bacteria performing DNRA may thus outcompete denitrification in this WWTP, limiting the biodegradation process. The alterations detected in bacterial populations involved in the removal of nitrogen and sulfur species evidenced a reduced quality of the released wastewater and may be good candidates for the following monitoring strategies and optimization of the wastewater treatment.

A gene cluster for taurine sulfur assimilation in an anaerobic human gut bacterium.

Aminoethylsulfonate (taurine) is widespread in the environment and highly abundant in the human body. Taurine and other aliphatic sulfonates serve as sulfur sources for diverse aerobic bacteria, which carry out cleavage of the inert sulfonate C-S bond through various O2-dependent mechanisms. Taurine also serves as a sulfur source for certain strict anaerobic fermenting bacteria. However, the mechanism of C-S cleavage by these bacteria has long been a mystery. Here we report the biochemical characterization of an anaerobic pathway for taurine sulfur assimilation in a strain of Clostridium butyricum from the human gut. In this pathway, taurine is first converted to hydroxyethylsulfonate (isethionate), followed by C-S cleavage by the O2-sensitive isethionate sulfo-lyase IseG, recently identified in sulfate- and sulfite-reducing bacteria. Homologs of the enzymes described in this study have a sporadic distribution in diverse strict and facultative anaerobic bacteria, from both the environment and the taurine-rich human gut, and may enable sulfonate sulfur acquisition in certain nutrient limiting conditions.