Improving the medium composition for the production of the natural blue-violet pigment violacein by a new Janthinobacterium sp. isolate.

The interest in natural compounds has increased primarily due to their beneficial health and environmental aspects. However, natural sources of some compounds, such as bluish pigments, are limited, requiring the development of efficient processes to meet commercial demands. This study isolated a blue-violet bacterium from spoiled cooked rice and identified it as a potential new species of Janthinobacterium through 16S rDNA analysis. Ultra-high performance liquid chromatography-tandem mass spectrometry analyses confirmed that the blue-violet pigment violacein was responsible for the bluish color. In laboratory conditions, different carbon and nitrogen sources were evaluated in submerged culture media to enhance pigment production. Glycerol did not result in significant pigment production by this strain, as expected from previous reports. Instead, a culture medium composed of yeast extract and fructose yielded higher pigment production, reaching about 113.68 ± 16.68 mg l-1 after 120 h. This result provides crucial insights for future studies aiming for sustainable and commercially viable violacein production. Based on a bioeconomy concept, this approach has the potential to supply natural and economic bluish pigments for various industrial sectors, including pharmaceutical, cosmetic, and food.

Genomics, Proteomics, and Antifungal Activity of Chitinase from the Antarctic Marine Bacterium Curtobacterium sp. CBMAI 2942.

This study aimed to evaluate the genomic profile of the Antarctic marine Curtobacterium sp. CBMAI 2942, as well as to optimize the conditions for chitinase production and antifungal potential for biological control. Assembly and annotation of the genome confirmed the genomic potential for chitinase synthesis, revealing two ChBDs of chitin binding (Chi C). The optimization enzyme production using an experimental design resulted in a 3.7-fold increase in chitinase production. The chitinase enzyme was identified by SDS-PAGE and confirmed through mass spectrometry analysis. The enzymatic extract obtained using acetone showed antifungal activity against the phytopathogenic fungus Aspergillus sp. series Nigri CBMAI 1846. The genetic capability of Curtobacterium sp. CBMAI 2942 for chitin degradation was confirmed through genomic analysis. The basal culture medium was adjusted, and the chitinase produced by this isolate from Antarctica showed significant inhibition against Aspergillus sp. Nigri series CBMAI 1846, which is a tomato phytopathogenic fungus. This suggests that this marine bacterium could potentially be used as a biological control of agricultural pests.

Cultured and uncultured microbial community associated with biogas production in anaerobic digestion processes.

The search for sustainable development has increased interest in the improvement of technologies that use renewable energy sources. One of the alternatives in the production of renewable energy comes from the use of waste including urban solids, animal excrement from livestock, and biomass residues from agro-industrial plants. These materials may be used in the production of biogas, making its production highly sustainable and environmentally friendly. The present study aimed to evaluate the cultivated and uncultivated microbial community from a substrate (starter) used as an adapter for biogas production in anaerobic digestion processes. 16S rDNA metabarcoding revealed the domain of bacteria belonging to the phyla Firmicutes, Bacteroidota, Chloroflexi and Synergistota. The methanogenic group was represented by the phyla Halobacterota and Euryarchaeota. Through 16S rRNA sequencing of isolates recovered from the starter culture, the genera Rhodococcus (Actinobacteria phylum), Vagococcus, Lysinibacillus, Niallia, Priestia, Robertmurraya, Proteiniclasticum (Firmicutes phylum), and Luteimonas (Proteobacteria phylum) were identified, genera that were not observed in the metabarcoding data. The volatile solids, volatile organic acids, and total inorganic carbon reached 659.10 g kg-1, 717.70 g kg-1, 70,005.0 g kg-1, respectively. The cultured groups are involved in the metabolism of sugars and other compounds derived from lignocellulosic material, as well as in anaerobic methane production processes. The results demonstrate that culture-dependent approaches, such as isolation and sequencing, and culture-independent studies, such as the Metabarcoding approach, are complementary methodologies that, when integrated provide robust and comprehensive information about the microbial communities involved in processes of the production of biogas in anaerobic digestion processes.

Phosphate solubilization by Antarctic yeasts isolated from lichens.

Antarctica has a great diversity of microorganisms with biotechnological potential but is not very well Known about yeasts with phosphate solubilization activity. Thus, the aim of this study was to evaluate the ability of yeasts from Antarctica lichens to solubilize phosphate in vitro. In the screening, 147 yeasts were tested and 43 (29%) showed P solubilization in solid NBRIP medium at 15.0 °C, with a higher prevalence of positive genera Vishniacozyma, followed by Cystobasidium. Most of the positive yeasts were isolated from Usnea auratiacoatra, followed by Polycauliona regalis and Lecania brialmontii. Two strains with better activity after screening were selected for the solubilization in the liquid medium, Vishniacozyma victoriae 2.L15 and A.L6 (unidentified). Vishniacozyma victoriae 2.L15 exhibiting activities at 25.0 °C (29.91 mg/L of phosphate and pH 6.85) and at 30.0 °C (619.04 mg/L of phosphate and pH 3.73) and A.L6 strain at 25.0 °C (25.05 mg/L of phosphate and pH 6.69) and at 30.0 °C (31.25 mg/L of phosphate and pH 6.47). Of eight organic acids tested by HPLC, tartaric and acetic acids were detected during phosphate solubilization, with greater release in the period of 144 (2.13 mg/L) and 72 (13.72 mg/L) hours, respectively. Future studies to elucidate the presence of functional genes for P metabolism in lichens, as well as studies in the field of proteomics for the discovery of yeast proteins related to P solubilization are needed. Thus, the high prevalence of lichen-associated yeast communities probably contributed to the high frequency of phosphate-solubilizing isolates in this study.

Hydrogen and organic acid production from dark fermentation of cheese whey without buffers under mesophilic condition.

BioH2 production from cheese whey (CW) was evaluated in two acidogenic reactors, UASB and structured fixed-bed (FB), without pH adjustment, under mesophilic conditions, and OLR of 25-90 g COD/L.d. Stage 1 was conducted as a control experiment using sucrose. BioH2 production occurred under pH < 3.0 with maximum yields of 5.8 and 3.0 mol H2/mol sucroseconsumed for UASB and FB reactors, respectively. In Stage 2, CW was the only substrate and a negligible bioH2 production was observed. Nevertheless, a maximum lactic acid concentration of 9.6 g/L was obtained, indicating that pH adjustment can be non-essential for lactic acid production from CW. In Stage 3, a strategy to enrich hydrogenogenic biomass was conducted by initially feeding the reactors with sucrose and gradually replacing it by CW. This strategy brought better bioH2 results compared to Stage 2, but it could not bear over the long-term, as non-hydrogen producing bacteria became predominant.

Pigments from Antarctic bacteria and their biotechnological applications.

Pigments from microorganisms have triggered great interest in the market, mostly by their "natural" appeal, their favorable production conditions, in addition to the potential new chemical structures or naturally overproducing strains. They have been used in: food, feed, dairy, textile, pharmaceutical, and cosmetic industries. The high rate of pigment production in microorganisms recovered from Antarctica in response to selective pressures such as: high UV radiation, low temperatures, and freezing and thawing cycles makes this a unique biome which means that much of its biological heritage cannot be found elsewhere on the planet. This vast arsenal of pigmented molecules has different functions in bacteria and may exhibit different biotechnological activities, such as: extracellular sunscreens, photoprotective function, antimicrobial activity, biodegradability, etc. However, many challenges for the commercial use of these compounds have yet to be overcome, such as: the low stability of natural pigments in cosmetic formulations, the change in color when subjected to pH variations, the low yield and the high costs in their production. This review surveys the different types of natural pigments found in Antarctic bacteria, classifying them according to their chemical structure. Finally, we give an overview of the main pigments that are used commercially today.

Pharmaceutical biotechnological potential of filamentous fungi isolated from textile industry.

The need for more effective drugs for the treatment of infectious diseases as well as for general applications including wound healing and burn surgery, has guided efforts for the discovery of new compounds of medical interest. Microorganisms found in textile industrial waste have the ability to produce a variety of enzymes and/or secondary metabolites including molecules of pharmaceutical interest. The present work investigated the biotechnological potential of filamentous fungi isolated from textile industry wastewater for the production of collagenase and antimicrobial metabolites. From 28 isolates assayed, Sarocladium sp. ITF33 showed specific collagenolytic activity with values of 7.62 and 9.04 U mg-1 for the intracellular and extracellular fractions, respectively. The isolate Penicillium sp. ITF28 showed the best antimicrobial activity, reaching MIC ranging from 1.0 to 0.0625 mg mL-1 against five pathogenic bacteria. Molecular analyzes suggest that the isolate Sarocladium sp. ITF 33 can be considered a species not yet described. The results of the present work encourage studies of characterization and purification of the enzymes and secondary metabolites produced by the isolates found aiming future applications in the medical and pharmaceutical fields.

Antarctic lichens as a source of phosphate-solubilizing bacteria.

In association with lichens, bacteria can play key roles in solubilizing sources of inorganic phosphates that are available in the environment. In this study, the potential of bacteria isolated from 15 Antarctic lichen samples for phosphate solubilization was investigated. From 124 bacteria tested, 66 (53%) were positive for phosphate solubilization in solid NBRIP medium, with a higher prevalence of Pseudomonas, followed by Caballeronia and Chryseobacterium. Most of the phosphate-solubilizing bacteria were isolated from Usnea auratiacoatra, followed by Caloplaca regalis and Xanthoria candelaria. Two isolates showed outstanding performance, Pseudomonas sp. 11.LB15 and Pseudomonas sp. 1.LB34, since they presented solubilization in the temperature range from 15.0 to 30.0 °C, and maximum quantification of soluble phosphate at 25.0 °C was 511.21 and 532.07 mg/L for Pseudomonas sp. 11.LB15 and Pseudomonas sp. 1.LB34, respectively. At 30.0 °C soluble phosphate yield was 639.43 and 518.95 mg/L with pH of 3.74 and 3.87 for Pseudomonas sp. 11.LB15 and Pseudomonas sp. 1.LB34, respectively. Fumaric and tartaric acids were released during the solubilization process. Finally, bacteria isolated from Antarctic lichens were shown to have the potential for phosphate solubilization, opening perspectives for future application in the agricultural sector and contributing to reduce the use of chemical fertilizers.

Undecane production by cold-adapted bacteria from Antarctica.

In the last decades, efforts to reduce the use of fossil fuels have increased the search for alternative sustainable sources of renewable energy. In this scenario, hydrocarbons derived from fatty acids are among the compounds that have been drawing attention. The intracellular production of hydrocarbons by bacteria derived from cold environments such as the Antarctic continent is currently poorly investigated, as extremophilic microorganisms provide a great range of metabolic capabilities and may represent a key tool in the production of biofuels. The aim of this study was to explore the ability of bacterial cells derived from extreme environments to produce hydrocarbons with potential for further use as biofuels. Seven bacteria isolated from Antarctic samples were evaluated for hydrocarbon production using GC-MS approaches. Two isolates, identified as Arthrobacter livingstonensis 593 and Pseudoalteromonas arctica 628, were able to produce the hydrocarbon undecane (CH3-(CH2)9-CH3) in concentrations of 1.39 mg L-1 and 1.81 mg L-1, respectively. Results from the present work encourage further research focusing on the optimization of hydrocarbon production by the isolates identified as producers, which may be used in further aircraft biofuel production. This is the first report on the production of the undecane compound by bacteria isolated from waterlogged soil and sponge from Antarctica.

The influence of upflow velocity and hydraulic retention time changes on taxonomic and functional characterization in Fluidized Bed Reactor treating commercial laundry wastewater in co-digestion with domestic sewage.

A large-scale (19.8L) Fluidized Bed Reactor (FBR) operated for 592 days was used to assess the removal performance of linear alkylbenzene sulfonate (LAS). Adjustments in hydraulic retention time (HRT) (18 and 30 h), ethanol (50, 100, 200 mg L-1) and linear alkylbenzene sulfonate (LAS) concentration (6.3-24.7 mg L-1) with taxonomic and functional characterization of biomass using Whole Genome Shotgun Metagenomic (WGSM) represented a major step forward for optimizing biological treatments of LAS. In addition, the variation of the upflow velocity (0.5, 0.7 and 0.9 cm s-1) was investigated, which is a parameter that had not yet been correlated with the possibilities of LAS removal in FBR. Lower Vup (0.5 cm s-1) allied to higher ethanol concentration (200 mg L-1) resulted in lower LAS removal (29%) with predominance of methanogenic archaea and genes related to methanogenesis, while higher Vup (0.9 cm s-1) led to aerobic organisms and oxidative phosphorylation genes. An intermediate Vup (0.7 cm s-1) and higher HRT (30 h) favored sulfate reducing bacteria and genes related to sulfur metabolism, which resulted in the highest LAS (83%) and COD (77%) removal efficiency.

Exploring the genetic potential of a fosmid metagenomic library from an oil-impacted mangrove sediment for metabolism of aromatic compounds.

Aromatic hydrocarbons (AH) are widely distributed in nature, and many of them have been reported as relevant environmental pollutants and valuable carbon sources for different microorganisms. In this work, high-throughput sequencing of a metagenomic fosmid library was carried out to evaluate the functional and taxonomic diversity of genes involved in aromatic compounds degradation in oil-impacted mangrove sediments. In addition, activity-based approach and gas chromatography were used to assess the degradation potential of fosmid clones. Results indicated that AH degradation genes, such as monooxygenases and dioxygenases, were grouped into the following categories: anaerobic degradation of aromatic compounds (20.34%), metabolism of central aromatic intermediates (35.40%) and peripheral pathways for catabolism of aromatic compounds (22.56%). Taxonomic affiliation of genes related to aromatic compounds metabolism revealed the prevalence of the classes Alphaproteobacteria, Actinobacteria, Betaproteobacteria, Gammaproteobacteria and Deltaproteobacteria. Aromatic hydrocarbons (phenol, naphthalene, phenanthrene, pyrene and benzopyrene) were used as the only carbon source to screen clones with degradation potential. Of the 2500 clones tested, 48 showed some respiratory activity in at least one of the five carbon sources used. The hydrocarbon degradation ability of the top ten fosmid clones was confirmed by GC-MS. Further, annotation of assembled metagenomic fragments revealed ORFs corresponding to proteins and functional domains directly or indirectly involved in the aromatic compound metabolism, such as catechol 2,3-dioxygenase and ferredoxin oxidoreductase. Finally, these data suggest that the indigenous mangrove sediment microbiota developed essential mechanisms towards ecosystem remediation of petroleum hydrocarbon impact.

The metagenomic landscape of xenobiotics biodegradation in mangrove sediments.

Metagenomics is a powerful approach to study microorganisms present in any given environment and their potential to maintain and improve ecosystem health without the need of cultivating these microorganisms in the laboratory. In this study, we combined a cultivation-independent metagenomics approach with functional assays to identify the detoxification potential of microbial genes evaluating their potential to contribute to xenobiotics resistance in oil-impacted mangrove sediments. A metagenomic fosmid library containing 12,960 clones from highly contaminated mangrove sediment was used in this study. For assessment of metal resistance, clones were grown in culture medium with increasing concentrations of mercury. The analyses metagenomic library sequences revealed the presence of genes related to heavy metals and antibiotics resistance in the oil-impacted mangrove microbiome. The taxonomic profiling of these sequences suggests that at the genus level, Geobacter was the most abundant genus in our dataset. A functional screening assessment of the metagenomic library successfully detected 24 potential heavy metal tolerant clones, six of which were capable of growing with increased concentrations of mercury. The genetic characterization of selected clones allowed the detection of genes related to detoxification processes, such as chromate transport protein ChrA, haloacid dehalogenase-like hydrolase, lipopolysaccharide transport system, and 3-oxoacyl-[acyl-carrier-protein] reductase. Clones were capable of growing in medium containing increased concentrations of metals and antibiotics, but none manifested strong mercury removal from culture medium characteristic of mercuric reductase activity. These results suggest that resistance to xenobiotic stress varies greatly and that additional studies to elucidate the potential of metal biotransformation need to be carried out with the goal of improving bioremediation application.

Environmental change and predator diversity drive alpha and beta diversity in freshwater macro and microorganisms.

Global biodiversity is eroding due to anthropogenic causes, such as climate change, habitat loss, and trophic simplification of biological communities. Most studies address only isolated causes within a single group of organisms; however, biological groups of different trophic levels may respond in particular ways to different environmental impacts. Our study used natural microcosms to investigate the predicted individual and interactive effects of warming, changes in top predator diversity, and habitat size on the alpha and beta diversity of macrofauna, microfauna, and bacteria. Alpha diversity (i.e., richness within each bromeliad) generally explained a larger proportion of the gamma diversity (partitioned in alpha and beta diversity). Overall, dissimilarity between communities occurred due to species turnover and not species loss (nestedness). Nevertheless, the three biological groups responded differently to each environmental stressor. Microfauna were the most sensitive group, with alpha and beta diversity being affected by environmental changes (warming and habitat size) and trophic structure (diversity of top predators). Macrofauna alpha and beta diversity was sensitive to changes in predator diversity and habitat size, but not warming. In contrast, the bacterial community was not influenced by the treatments. The community of each biological group was not mutually concordant with the environmental and trophic changes. Our results demonstrate that distinct anthropogenic impacts differentially affect the components of macro and microorganism diversity through direct and indirect effects (i.e., bottom-up and top-down effects). Therefore, a multitrophic and multispecies approach is necessary to assess the effects of different anthropogenic impacts on biodiversity.

Microbial functional responses to long-term anthropogenic impact in mangrove soils.

Mangroves are coastal ecosystems of transition between terrestrial and marine environments, that have been particularly contaminated in the last decades. Organic compounds are part of these contaminants, which have increased in the environment due to industrial activities and accidental oil spills. These contaminants are toxic to higher organisms, but microorganisms can metabolize most of these compounds and thus offer a tool for bioremediation purposes. The aim of the present study was to characterize the microbial potential and activity for degradation of aromatic compounds in sediment samples from mangroves using metagenomic and metatranscriptomic approaches. Sediment samples were collected for DNA and RNA extraction from each of the mangrove sites: highly oil-impacted (Oil Mgv), anthropogenically impacted (Ant Mgv) and pristine (Prs Mgv) mangrove. Hydrocarbon concentrations in Oil Mgv sediments were higher than those observed in Ant Mgv and Prs Mgv. Genes and transcripts associated with aromatic compound degradation, particularly the meta and ortho-pathways, were more abundant in Oil Mgv and Ant Mgv suggesting that many of the aromatic compounds are being aerobically degraded by the microbiome in these sites. Functions involved in the degradation of aromatic compounds were also found in pristine site, although in lower abundance. Members of the genera Aromatoleum, Desulfococcus, Desulfatibacillum, Desulfitobacterium and Vibrio were actively involved in the detoxification of sediments affected by the oil spill. Results obtained from this study provided strong evidence that microbial degradation of aromatic compounds plays an active role in the biological response to mangrove sediment pollution and subsequent ecosystem recovery.

Ammonium removal from high-salinity oilfield-produced water: assessing the microbial community dynamics at increasing salt concentrations.

Water generated during oil exploration is chemically complex and contains high concentrations of ammonium and, in some cases, high salinity. The most common way to remove ammonium from effluent is a biological process, which can be performed by different routes and different groups of microorganisms. However, the presence of salts in the effluents could be an inhibiting factor for biological processes, interfering directly with treatment. This study aimed to evaluate changes in the profile of a microbial community involved in the process of ammonium removal when subjected to a gradual increase of salt (NaCl), in which the complete inhibition of the ammonium removal process occurred at 125 g L-1 NaCl. During the sludge acclimatization process, samples were collected and submitted to denaturing gradient gel electrophoresis (DGGE) and massive sequencing of the 16S ribosomal RNA (rRNA) genes. As the salt concentration increased in the reactor, a change in the microbial community was observed by the DGGE band profiles. As a result, there was a reduction in the presence of bacterial populations, and an increase in archaeal populations was found. The sequencing data suggested that ammonium removal in the reactor was carried out by different metabolic routes by autotrophic nitrifying bacteria, such as Nitrosococcus, Nitrosomonas, Nitrosovibrio, Nitrospira, and Nitrococcus; ammonium-oxidizing archaea Candidatus nitrosoarchaeum; ANAMMOX microorganisms, such as Candidatus brocadia, Candidatus kuenenia, and Candidatus scalindua; and microorganisms with the potential to be heterotrophic nitrifying, such as Paracoccus spp., Pseudomonas spp., Bacillus spp., Marinobacter sp., and Alcaligenes spp.

Functional metagenomics of oil-impacted mangrove sediments reveals high abundance of hydrolases of biotechnological interest.

Mangroves are located in coastal wetlands and are susceptible to the consequences of oil spills, what may threaten the diversity of microorganisms responsible for the nutrient cycling and the consequent ecosystem functioning. Previous reports show that high concentration of oil favors the incidence of epoxide hydrolases and haloalkane dehalogenases in mangroves. This finding has guided the goals of this study in an attempt to broaden the analysis to other hydrolases and thereby verify whether oil contamination interferes with the prevalence of particular hydrolases and their assigned microorganisms. For this, an in-depth survey of the taxonomic and functional microbial diversity recovered in a fosmid library (Library_Oil Mgv) constructed from oil-impacted Brazilian mangrove sediment was carried out. Fosmid DNA of the whole library was extracted and submitted to Illumina HiSeq sequencing. The resulting Library Oil_Mgv dataset was further compared with those obtained by direct sequencing of environmental DNA from Brazilian mangroves (from distinct regions and affected by distinct sources of contamination), focusing on hydrolases with potential use in biotechnological processes. The most abundant hydrolases found were proteases, esterases and amylases, with similar occurrence profile in all datasets. The main microbial groups harboring such hydrolase-encoding genes were distinct in each mangrove, and in the fosmid library these enzymes were mainly assigned to Chloroflexaceae (for amylases), Planctomycetaceae (for esterases) and Bradyrhizobiaceae (for proteases). Assembly and analysis of Library_Oil Mgv reads revealed three potentially novel enzymes, one epoxide hydrolase, one xylanase and one amylase, to be further investigated via heterologous expression assays.

Genomic and chemical insights into biosurfactant production by the mangrove-derived strain Bacillus safensis CCMA-560.

Many Bacillus species can produce biosurfactant, although most of the studies on lipopeptide production by this genus have been focused on Bacillus subtilis. Surfactants are broadly used in pharmaceutical, food and petroleum industry, and biological surfactant shows some advantages over the chemical surfactants, such as less toxicity, production from renewable, cheaper feedstocks and development of novel recombinant hyperproducer strains. This study is aimed to unveil the biosurfactant metabolic pathway and chemical composition in Bacillus safensis strain CCMA-560. The whole genome of the CCMA-560 strain was previously sequenced, and with the aid of bioinformatics tools, its biosurfactant metabolic pathway was compared to other pathways of closely related species. Fourier transform infrared (FTIR) and high-resolution TOF mass spectrometry (MS) were used to characterize the biosurfactant molecule. B. safensis CCMA-560 metabolic pathway is similar to other Bacillus species; however, some differences in amino acid incorporation were observed, and chemical analyses corroborated the genetic results. The strain CCMA-560 harbours two genes flanked by srfAC and srfAD not present in other Bacillus spp., which can be involved in the production of the analogue gramicidin. FTIR and MS showed that B. safensis CCMA-560 produces a mixture of at least four lipopeptides with seven amino acids incorporated and a fatty acid chain with 14 carbons, which makes this molecule similar to the biosurfactant of Bacillus pumilus, namely, pumilacidin. This is the first report on the biosurfactant production by B. safensis, encompassing the investigation of the metabolic pathway and chemical characterization of the biosurfactant molecule.

Shifts in structure and dynamics of the soil microbiome in biofuel/fuel blend-affected areas triggered by different bioremediation treatments.

The use of biofuels has grown in the last decades as a consequence of the direct environmental impacts of fossil fuel use. Elucidating structure, diversity, species interactions, and assembly mechanisms of microbiomes is crucial for understanding the influence of environmental disturbances. However, little is known about how contamination with biofuel/petrofuel blends alters the soil microbiome. Here, we studied the dynamics in the soil microbiome structure and composition of four field areas under long-term contamination with biofuel/fossil fuel blends (ethanol 10% and gasoline 90%-E10; ethanol 25% and gasoline 75%-E25; soybean biodiesel 20% and diesel 80%-B20) submitted to different bioremediation treatments along a temporal gradient. Soil microbiomes from biodiesel-polluted areas exhibited higher richness and diversity index values and more complex microbial communities than ethanol-polluted areas. Additionally, monitored natural attenuation B20-polluted areas were less affected by perturbations caused by bioremediation treatments. As a consequence, once biostimulation was applied, the degradation was slower compared with areas previously actively treated. In soils with low diversity and richness, the impact of bioremediation treatments on the microbiomes was greater, and as a result, the hydrocarbon degradation extent was higher. The network analysis showed that all abundant keystone taxa corresponded to well-known degraders, suggesting that the abundant species are core targets for biostimulation in soil remediation processes. Altogether, these findings showed that the knowledge gained through the study of microbiomes in contaminated areas may help design and conduct optimized bioremediation approaches, paving the way for future rationalized and efficient pollutant mitigation strategies.

One versus two-stage codigestion of sugarcane vinasse and glycerol: Assessing combinations at mesophilic and (hyper) thermophilic conditions.

Sugarcane vinasse exits the distillation process at high temperatures, which may differ from the optimal temperatures for dark fermentation and anaerobic digestion. A 15 °C temperature increase, for example, stops sugarcane vinasse methane generation, making distillery vinasse digestion complicated. Conversely, in other aspects, co-digesting vinasse and glycerol has been proven to stabilize methane production from vinasse because of sulfate dilution. However, glycerol has not been tested to stabilize vinasse digestion under temperature changes. Thus, this study compared the effects of different temperature settings on the co-digestion of 10 g COD L-1 of vinasse and glycerol (50 %:50 % on a COD basis) in anaerobic fluidized bed reactors (AFBR), i.e., an acidogenic and a methanogenic one-stage AFBRs operated at 55, 60, and 65 °C, and two methanogenic AFBRs fed both with acidogenic effluent (one operated at room temperature (25 °C) and the other at 55, 60, and 65 °C). The co-digestion provided steady methane generation at all AFBRs, with methane production rates ranging from 2.27 to 2.93 L CH4 d-1 L-1, whether in one or two stages. A feature of this research was to unravel the black box of the role of sulfate in the digestion of sugarcane vinasse, which was rarely studied. Desulfovibrio was the primary genus degrading 1,3-propanediol into 3-hydroxypropanoate after genome sequencing. Phosphate acetyltransferase (EC: 2.3.1.8, K00625) and acetate kinase (EC: 2.7.2.1, K00925) genes were also found, suggesting propionate was metabolized. In practical aspects, regarding the two-stage systems, the thermophilic-mesophilic (acidogenic-methanogenic) configuration is best for extracting additional value-added products because 1,3-propanediol may be recovered at high yields with steady methane production at reduced energy expenditure in a reactor operated at room temperature. However, the one-stage design is best for methane generation per system volume since it remained stable with rising temperatures, and all systems presented similar methane production rates.

Two problems in one shot: Vinasse and glycerol co-digestion in a thermophilic high-rate reactor to improve process stability even at high sulfate concentrations.

Anaerobic co-digestion (AcoD) of sugarcane vinasse and glycerol can be profitable because of the destination of two biofuel wastes produced in large quantities in Brazil (ethanol and biodiesel, respectively) and the complementary properties of these substrates. Thus, the objective of this study was to assess the effect of increasing the organic loading rate (OLR) from 2 to 20 kg COD m-3 d-1 on the AcoD of vinasse and glycerol (50 %:50 % on a COD basis) in a thermophilic (55 °C) anaerobic fluidized bed reactor (AFBR). The highest methane production rate was observed at 20 kg COD m-3 d-1 (8.83 L CH4 d-1 L-1), while the methane yield remained stable at around 265 NmL CH4 g-1 CODrem in all conditions, even when influent vinasse reached 1811 mg SO42- L-1 (10 kg COD m-3 d-1). Sulfate was not detected in the effluent. Bacterial genera related to sulfate removal, such as Desulfovibrio and Desulfomicrobium, were observed by means of shotgun metagenomic sequencing at 10 kg COD m-3 d-1, as well as the acetoclastic archaea Methanosaeta and prevalence of genes encoding enzymes related to acetoclastic methanogenesis. It was concluded that process efficiency and methane production occurred even in higher sulfate concentrations due to glycerol addition.