Understanding microbiome dynamics and functional responses during acidogenic fermentation of sucrose and sugarcane vinasse through metatranscriptomic analysis.

Improving anaerobic digestion of sugarcane vinasse - a high-strength wastewater from ethanol distillation - is a subject of great interest, in view of the reduction of the pollutants and recovery of methane and valuable metabolites as byproducts. Through metatranscriptomic analysis, this study evaluated the active microbiome and metabolic pathways in a continuous acidogenic reactor: Stage 1S (control): 100% sucrose-based substrate (SBS); Stage 2SV (acclimation): 50% SBS and 50% vinasse; Stage 3V: 100% vinasse. Metatranscriptome obtained from each Stage was subjected to taxonomic and functional annotations. Under SBS feeding, pH dropped to pH 2.7 and biohydrogen production was observed. As vinasse was added, pH increased to 4.1-4.5, resulting in community structure and metabolite changes. In Stage 3V, biohydrogen production ceased, and propionate and acetate prevailed among the volatile fatty acids. Release of homoacetogenesis enzymes by Clostridium ljungdahlii and of uptake hydrogenase (EC 1.12.99.6) by Pectinatus frisingensis were linked to hydrogen consumption in Stages 2SV and 3V. Metabolic pathways of vinasse compounds, such as carbohydrates, malate, oxalate, glycerol, sulfate and phenol, were investigated in detail. In pyruvate metabolism, gene transcripts of oadA (oxaloacetate decarboxylase) and mdh (malate dehydrogenase), were upregulated in Stage 3V, being mostly attributed to P. frisingensis. Acetate formation from vinasse degradation was mainly attributed to Megasphaera and Clostridium, and propionate formation to P. frisingensis. Glycerol removal from vinasse exceeded 99%, and gene transcripts encoding for glpF (glycerol uptake facilitator protein), glpK (glycerol kinase) and glpABC (glycerol-3-phosphate dehydrogenase) were expressed mostly by Pectinatus and Prevotella. mRNA profiling showed that active bacteria and gene expression greatly changed when vinasse replaced sucrose, and Pectinatus was the main active bacterium degrading the searched compounds from vinasse. The identification of the main metabolic routes and the associated microorganisms achieved in this work contributes with valuable information to support further optimization of fermentation towards the desired metabolites.

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.

Microbial and functional characterization of granulated sludge from full-scale UASB thermophilic reactor applied to sugarcane vinasse treatment.

Considering the scarcity of data in the literature regarding phylogenetic and metabolic composition of different inocula, especially those from thermophilic conditions, this research aimed at characterizing the microbial community and preferable metabolic pathways of an UASB reactor sludge applied to the thermophilic treatment (55°C) of sugarcane vinasse, by means of shotgun metagenomics. After its metabolic potential was depicted, it was possible to observe several genes encoding enzymes that are of great importance to anaerobic digestion processes with different wastes as substrate, especially regarding the biodegradation of carbohydrates and ligninolytic compounds, glycerolypids, volatile fatty acids and alcohols metabolism and biogas (H2 and CH4) production. The genera identified in higher relative abundances for Bacteria domain were Sulfirimonas (37.52 ± 1.8%), possibly related to the sludge endogenic activity due to its strong relation with a peptidoglycan lyase enzymes family, followed by Fluviicola (5.01 ± 1.0%), Defluviitoga (4.36 ± 0.2%), Coprothermobacter (4.32 ± 0.5%), Fervidobacterium (2.93 ± 0.3%), Marinospirillum (2.75 ± 0.2%), Pseudomonas (2.14 ± 0.2%) and Flavobacterium (1.78 ± 0.1%), mostly related with carbohydrates fermentations and/or H2 production. For Archaea domain, Methanosarcina (0.61 ± 0.1%), Methanothermobacter (0.38 ± 0.0%), Methanoculleus (0.30 ± 0.1%), Thermococcus (0.03 ± 0.0%), Methanolobus (0.02 ± 1.8%), Methanobacterium (0.013 ± 0.0%), Aciduliprofundum and Pyrococcus (0.01 ± 0.0%) were the most dominant ones, being Methanosarcina the most related with methanogenesis. It was concluded that the robust inoculum description performed in this study may subside future biotechnological researches by using similar inocula (UASB sludges), focusing on the obtainment of value-added by-products by means of anaerobic digestion, such as volatile fatty acids, alcohols and biogas (H2 and CH4), by using several types of waste as substrate.

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.

Interactive analysis of biosurfactants in fruit-waste fermentation samples using BioSurfDB and MEGAN.

Agroindustrial waste, such as fruit residues, are a renewable, abundant, low-cost, commonly-used carbon source. Biosurfactants are molecules of increasing interest due to their multifunctional properties, biodegradable nature and low toxicity, in comparison to synthetic surfactants. A better understanding of the associated microbial communities will aid prospecting for biosurfactant-producing microorganisms. In this study, six samples of fruit waste, from oranges, mangoes and mixed fruits, were subjected to autochthonous fermentation, so as to promote the growth of their associated microbiota, followed by short-read metagenomic sequencing. Using the DIAMOND+MEGAN analysis pipeline, taxonomic analysis shows that all six samples are dominated by Proteobacteria, in particular, a common core consisting of the genera Klebsiella, Enterobacter, Stenotrophomonas, Acinetobacter and Escherichia. Functional analysis indicates high similarity among samples and a significant number of reads map to genes that are involved in the biosynthesis of lipopeptide-class biosurfactants. Gene-centric analysis reveals Klebsiella as the main assignment for genes related to putisolvins biosynthesis. To simplify the interactive visualization and exploration of the surfactant-related genes in such samples, we have integrated the BiosurfDB classification into MEGAN and make this available. These results indicate that microbiota obtained from autochthonous fermentation have the genetic potential for biosynthesis of biosurfactants, suggesting that fruit wastes may provide a source of biosurfactant-producing microorganisms, with applications in the agricultural, chemical, food and pharmaceutical industries.

DNA Metabarcoding from Microbial Communities Recovered from Stream and Its Potential for Bioremediation Processes.

Urban waste (UW) has caused a series of problems regarding its management. UW comprises domestic, hospital and industrial residues, which makes the destination of this waste a matter of concern, as it may contain a variety of highly toxic environmental polluters. Deactivated dumps can represent sources of contamination of the environment that surround these deposits, harming rivers and inhabiting organisms. Knowledge of the microbial profile of water bodies that can be affected by these toxic residues is essential for the development of alternatives and improvements in treatments applied in rivers and streams. In this sense, this work aimed to analyze the microbial community present in sediments of the Arroio Dourado stream in the municipality of Foz do Iguaçu, a stream located near a deactivated open-air dump. 16S rDNA metabarcoding suggested the dominance of acidogenic bacteria belonging to Acidobacteriota phylum, followed by less abundant phyla Actinobacteriota, Myxococcota, Chloroflexi and a small community of sulfate reducers (Desulfobacteriota). However, more than 50% of amplicon sequence variants (ASVs) were not taxonomically classified. In addition, an expressive abundance was attributed to the genus Anaeromyxobacter, a metabolically versatile group, which can thrive in the presence of polluting compounds present in the deactivated landfill. Thus, a possible stream treatment process can be developed. In addition, culture media can be developed for the recovery of taxonomic groups identified involved in the biodegradation of organic compounds. The results presented expand the knowledge of bacterial diversity in sediment samples recovered from the Arroio Dourado stream.

New Insights into Controlling Homoacetogenesis in the Co-digestion of Coffee Waste: Effect of Operational Conditions and Characterization of Microbial Communities.

In this research batch reactors were operated with coffee processing waste and autochthonous microbial consortium, and a taxonomic and functional analysis was performed for phase I of stabilization of maximum H2 production and for phase II of maximum H2 consumption. During phase I, the reactor's operating conditions were pH 4.84 to 8.18, headspace 33.18% to 66.82%, and pulp and husk from 6.95 to 17.05 g/L. These assays continued for phase II, with initial pH conditions of 5.8-8.1, headspace of 33.18-66.82%, and pulp and husk remaining from phase I. The highest homoacetogenesis was observed in assay 5 with pH 7.7, 40% headspace, and 15 g/L of pulp and husk (initial concentrations of phase I). A relative abundance of Clostridium 41%, Lactobacillus 20% and Acetobacter 14% was observed in phase I. In phase II, there was a change in relative abundance of 21%, 63%, and 1%, respectively, and functional genes involved with autotrophic (formyltetrahydrofolate synthase) and heterotrophic (enolase) homoacetogenesis, butanol (3-hydroxybutyryl-CoA dehydrogenase), and propionic acid (propionate CoA-transferase) were identified. This study provides a new and amplified insight into the physicochemical and microbiological factors, which can be used to propose adequate operational conditions to maximize the bioenergy production and reduce homoacetogenesis in biological reactors.

Extremophilic taxa predominate in a microbial community of photovoltaic panels in a tropical region.

Photovoltaic panels can be colonized by a highly diverse microbial diversity, despite life-threatening conditions. Although they are distributed worldwide, the microorganisms living on their surfaces have never been profiled in tropical regions using 16S rRNA high-throughput sequencing and PICRUst metagenome prediction of functional content. In this work, we investigated photovoltaic panels from two cities in southeast Brazil, Sorocaba and Itatiba, using these bioinformatics approach. Results showed that, despite significant differences in microbial diversity (p < 0.001), the taxonomic profile was very similar for both photovoltaic panels, dominated mainly by Proteobacteria, Bacteroidota and lower amounts of Cyanobacteria phyla. A predominance of Hymenobacter and Methylobacterium-Methylorubrum was observed at the genus level. We identified a microbial common core composed of Hymenobacter, Deinococcus, Sphingomonas, Methylobacterium-Methylorubrum, Craurococcus-Caldovatus, Massilia, Noviherbaspirillum and 1174-901-12 sharing genera. Predicted metabolisms focused on specific genes associated to radiation and desiccation resistance and pigments, were detected in members of the common core and among the most abundant genera. Our results suggested that taxonomic and functional profiles investigated were consistent with the harsh environment that photovoltaic panels represent. Moreover, the presence of stress genes in the predicted functional content was a preliminary evidence that microbes living there are a possibly source of metabolites with biotechnological interest.

Simultaneous nitrification-denitrification (SND) using a thermoplastic gel as support: pollutants removal and microbial community in a pilot-scale biofilm membrane bioreactor.

In this study, experiments were carried out to treat sanitary wastewater in a biofilm membrane bioreactor using a thermoplastic gel as a support to assist the nitrification-denitrification process. For this purpose, the system was operated in two different dissolved oxygen concentrations (2.3 ± 0.2 and 0.9 ± 0.3 mg O2/L for Phases I and II, respectively) and the removal of organic compounds and nitrogen, as well as the microbial community in suspended biomass and biofilm were evaluated. The MB-MBR system was able to withstand raw wastewater variations and maintaining a low permeate COD concentration (18 mg/L) even at low DO concentrations. On the other hand, it was found that oxygen concentration significantly influenced the process of nitrogen conversion. In Phase I the average removal of total nitrogen was 18 ± 8%, while in Phase II it increased to 66 ± 11%. The denitrification rate was two times higher (7.8 mg NO3--N/h) at low dissolved oxygen, with a significant contribution of the biofilm (41%). Additionally, the high-throughput 16S rDNA sequencing showed that the oxygen concentration was determinant for arrangement patterns of the samples and not the sampling site (suspended biomass and support material). Thiothrix, Comamonas, Rhodobacter, Mycobacterium, Thermomonas, Sphingobium, Sphigopyxis, Pseudoxanthomonas, Nitrospira and, Novosphingobium were the main genera regarding the nitrogen cycle.

Reactors and active biomass potential as inoculum for nitrogen removal.

The potential of three different kind of reactors and active biomass to be used as inoculum for nitrogen removal was verified. Sludge samples were collected from a Membrane Bioreactor (MBR), a previous tank of a Moving Bed Biofilm Reactor (MBBR) and a Trickling Filter (TF). Samples were compared according to bacterial activity in batch tests and their microbiology (16 s rRNA sequences). The microorganisms examined were: AOB, NOB, anammox bacteria and OHO. Results showed that the richest sample was from MBR (Chao value equals 581). However, the bacterial activity was greater in MBBR sample (qAOO,NH4 equals 0.002 mgN·mgVSS-1·h-1; qNOO,NO2_NO3 equals 0.001 mgN·mgVSS-1·h-1 and qNOX_N2,SB equals 10.0 mgN·mgVSS-1·h-1). Therefore, MBBR WWTP was shown to have the best inoculum and operating conditions for nitrogen conversion and removal. Besides, if aeration is provided as low as necessary for AOB to start the activity in denitrification tank, simultaneous partial nitrification, and denitrification (SPND) can occur.

Microbial and functional characterization of an allochthonous consortium applied to hydrogen production from Citrus Peel Waste in batch reactor in optimized conditions.

Energy recovery from lignocellulosic waste has been studied as an alternative to the problem of inappropriate waste disposal. The present study aimed at characterizing the microbial community and the functional activity of reactors applied to H2 production through lignocellulosic waste fermentation in optimized conditions. The latter were identified by means of Rotational Central Composite Design (RCCD), applied to optimize allochthonous inoculum concentration (2.32-5.68 gTVS/L of granular anaerobic sludge), pH (4.32-7.68) and Citrus Peel Waste (CPW) concentration (1.55-28.45 g/L). After validation, the conditions identified for optimal H2 production were 4 gSTV/L of allochthonous inoculum, 29.8 g/L of CPW (substrate) and initial pH of 8.98. In these conditions, 48.47 mmol/L of H2 was obtained, which is 3.64 times higher than the concentration in unoptimized conditions (13.31 mmol H2/L using 15 g/L of CPW, 2 gTVS/L of allochthonous inoculum, pH 7.0). Acetogenesis was the predominant pathway, and maximal concentrations of 3,731 mg/L of butyric acid and 3,516 mg/L of acetic acid were observed. Regarding the metataxonomic profile, Clostridium genus was dramatically favored in the optimized condition (79.78%) when compared to the allochthonous inoculum (0.43%). It was possible to identify several genes related to H2 (i.e dehydrogenases) and volatile fatty acids (VFA) production and with cellulose degradation, especially some CAZymes from the classes Auxiliary Activities, Glycoside Hydrolases and Glycosyl Transferase. By means of differential gene expression it was observed that cellulose degradation and acetic acid production pathways were overabundant in samples from the optimized reactors, highlighting endo-ß-1,4-glucanase/cellulose, endo-ß-1,4-xylanase, ß-glucosidase, ß-mannosidase, cellulose ß-1,4-cellobiosidase, cellobiohydrolase, and others, as main the functions.

Sulfate removal rate and metal recovery as settling precipitates in bioreactors: Influence of electron donors.

Four down-flow structured bed bioreactors were operated targeting biological sulfate-reduction and metal recovery. Three different electron donors were tested: glycerol (R1), lactate (R2), sucrose (R3), and a blend of the previous three (R4) with an increasing copper influent load (5, 15, and 30 mg Cu2+.L-1). Copper inhibited sulfate-reduction in R1 (15 mg Cu2+.L-1) and R3 (5 mg Cu2+.L-1), but the fermentative activity was not affected. R2 and R4 were not inhibited by the copper influent concentration. R2 provided the highest sulfate reduction rate (1767.3 ± 240.1 mg SO42-.L.day-1). Nonetheless, the accumulation of settling precipitates was 22 % higher in R4 than in R2, indicating the former yielded the highest metal recovery as settling precipitates (24.8 g FSS.L-1, 25 % Fe2+, 5% Cu2+). 16S rRNA sequencing showed highest diversity of sulfate-reducing bacteria in R2. A predominance of sulfate-reducing and fermentative bacteria with more similarity was observed between microbial populations in R1 and R4, despite the difference in toxicity thresholds. Hence, the electron donor influenced not only the biological sulfate reduction, but also metal toxicity thresholds and metal recovery as settling precipitates.

Microbiome taxonomic and functional profiles of two domestic sewage treatment systems.

Anaerobic systems for domestic sewage treatment, like septic tanks and anaerobic filters, are used in developing countries due to favorable economic and functional features. The anaerobic filter is used for the treatment of the septic tank effluent, to improve the COD removal efficiency of the system. The microbial composition and diversity of the microbiome from two wastewater treatment systems (factory and rural school) were compared through 16S rRNA gene sequencing using MiSeq 2 × 250 bp Illumina sequencing platform. Additionally, 16S rRNA data were used to predict the functional profile of the microbial communities using PICRUSt2. Results indicated that hydrogenotrophic methanogens, like Methanobacterium, were found in higher abundance in both systems compared to acetotrophic methanogens belonging to Methanosaeta genus. Also, important syntrophic microorganisms (Smithella, Syntrophus, Syntrophobacter) were found in the factory and rural school wastewater treatment systems. Microbial communities were also compared between stages (septic tank and anaerobic filter) of each wastewater treatment stage, revealing that, in the case of the rural school, both microbial communities were quite similar most likely due to hydraulic short-circuit issues. Meanwhile, in the factory, microbial communities from the septic tank and anaerobic filter were different. The school system showed lower COD removal rates (2-30%), which were probably related to a higher abundance of Firmicutes members in addition to the hydraulic short-circuit and low abundance of Chloroflexi members. On the other hand, the fiberglass factory presented higher COD removal rates (60-83%), harboring phyla reported as the core microbiome of anaerobic digesters (Bacteroidetes, Chloroflexi, and Proteobacteria phyla). The knowledge of the structure and composition of wastewater treatment systems may provide support for the improvement of the pollutant removal in anaerobic process.

Orange Bagasse Pellets as a Carbon Source for Biobutanol Production.

Due to the environmental concerns, the conversion of lignocellulosic waste can be the key to produce bioproducts and biofuels such as butanol. This study aimed to present and evaluate orange bagasse pellets (OBP) as a carbon source to produce butan-1-ol production via ABE fermentation using Clostridium beijerinckii. These bagasse pellets were characterized, holocellulose (18.99%), alfacellulose (5.37%), hemicellulose (13.62%), lignin (6.16%), pectin (7.21%), protein (3.14%), and was tested under three different pretreatments, which were the following: (a) ultrasound, (b) autohydrolysis, and (c) acid-diluted hydrolysis followed by enzymatic hydrolysis to verify an amount of fermentable total reducing sugars. ANOVA was used and pretreatments followed by enzymatic hydrolysis do not enhance a significant amount of available sugars compared to raw bagasse. The ABE fermentation was carried out in batch reactors at 37 °C under agitation of 160 rpm and anaerobic conditions, using OBP without treatment followed by enzymatic hydrolysis. Using a non-mutant microorganism, the fermentation achieved butyric acid yields of 3762.68 mg L-1 for control and 2488.82 mg L-1 for OBP and the butanol production was 63.86 mg L-1 and 196.80 mg L-1 for OBP and the control (glucose) assay, respectively. The results of this solvent's production have shown that OBP has the potential for ABE fermentation and a promising feedstock.

Endophytic fungi isolated from Brazilian medicinal plants as potential producers of antioxidants and their relations with anti-inflammatory activity.

In this study, 19 endophytic fungi were isolated from Lafoensia pacari, Guazuma ulmifolia, Campomanesia xanthocarpa and Siparuna guianensis. Seventeen strains were molecularly identified as belonging to the genera Colletotrichum, Diaporthe, Bjerkandera, Talaromyces, Cochliobolus, Phaeophlebiopsis, Curvularia, and Xylaraceae. Assays for detecting antioxidant activity were performed by free radical scavenging activity using the DDPH and ABTS + methods. Based on the results with DPPH, two strains were selected to evaluate the presence of flavonoids and anti-inflammatory activity. A strong positive correlation was found between these activities and the presence of flavonoids. The anti-inflammatory activity of endophytic fungi is under explored; however, the Talaromyces obtained the best result of 87.33% protection of erythrocytes and Colletotrichium of 60.71%. This study demonstrated that endophytic fungi associated with selected plants are potential sources of novel antioxidant products.

Dynamics and response of microbial diversity to nutritional conditions in denitrifying bioreactor for linear alkylbenzene sulfonate removal.

The aim of this study was to evaluate the microbial structure and phylogenetic diversity under the influence of nutritional conditions and hydraulic retention time (HRT) in fluidized bed reactors (FBR), operated in short HRT (8 h - FBR8; 12 h - FBR12) for linear alkylbenzene sulfonate (LAS) removal from laundry wastewater. After each phase, biofilm samples from FBR8 and FBR12 were submitted to microbial sequencing by Mi-Seq Illumina®. Higher LAS removal rates were observed after 313 days, achieving 99 ± 3% in FBR12 (22.5 ± 5.9 mg LAS/L affluent) and 93 ± 12% in FBR8 (20.6 ± 4.4 mg LAS/L affluent). Different modifications involving genera of bacteria were observed throughout the reactors operation. The identified microorganisms were, mostly, related to LAS degradation and nitrogen conversion such as Dechloromonas, Flavobacterium, Pseudomonas, and Zoogloea.

Influence of pulp on the microbial diversity during cupuassu fermentation.

Cupuassu (Theobroma grandiflorum Schum) is a fruit belonging to the same genus as cocoa and, through seed fermentation, a chocolate-like product called "the cupulate" is obtained. The pulp is removed from the seeds before fermentation because its abundance hinders the process. Unlike cocoa, little is known about the microbial diversity involved in cupuassu fermentation. The goal of this study was to explore the use of next-generation sequencing to identify the yeasts and bacteria communities involved in cupuassu seed fermentation on three different pulp concentrations (0, 7.5, and 15%) as well as two turning schemes on the microbial growth. In order to do that, a massive sequencing of the 16S and ITS4 rRNA region (S) using the Illumina MiSeq Platform identified some genera of bacteria and yeasts, respectively, in the fermentation environment. Taxonomic analyses of both communities, especially at the genus level, revealed a predominance of yeasts such as Pichia and Hanseniaspora, and bacteria such as Acetobacter and Lactobacillus. A predominance of bacteria over yeasts diversity was observed in the experiments with higher pulp concentrations (15%). The physicochemical analysis showed that fermentation of samples with 15% pulp exhibited longer fermentation times, the highest temperatures, and elevated production of organic acids such as acetic acid, a precursor of flavor. In addition, the turning applied every 24 h to the mass slightly favored the formation of flavor precursors. It seems that the abundance and composition of cupuassu pulp, rich in organic compounds, can influence the diversity of some populations of yeasts. Some of those compounds identified in previous studies are terpenes with antimicrobial activity. More studies will be necessary to confirm if the presence of terpenes compounds in the cupuassu pulp exert some inhibitory action on microorganism diversity.

Land Use and Seasonal Effects on the Soil Microbiome of a Brazilian Dry Forest.

Drylands occupy approximately 41% of the Earth's terrestrial surface. Climate change and land use practices are expected to affect biogeochemical cycling by the soil microbiome in these ecosystems. Understanding how soil microbial community might respond to these drivers is extremely important to mitigate the processes of land degradation and desertification. The Caatinga, an exclusively Brazilian biome composed of an extensive seasonal tropical dry forest, is exposed to variable spatiotemporal rainfall patterns as well as strong human-driven pressures. Herein, an integrated analysis of shotgun metagenomics approach coupled to meteorological data was employed to unravel the impact of seasonality and land use change on soil microbiome from preserved and agriculture-affected experimental fields in Caatinga drylands. Multivariate analysis suggested that microbial communities of preserved soils under seasonal changes were shaped primarily by water deficit, with a strong increase of Actinobacteria and Proteobacteria members in the dry and rainy seasons, respectively. In contrast, nutrient availability notably played a critical role in driving the microbial community in agriculture-affected soils. The strong enrichment of bacterial genera belonging to the poorly-known phylum Acidobacteria ('Candidatus Solibacter' and 'Candidatus Koribacter') in soils from dry season affected by ferti-irrigation practices presupposes a contrasting copiotrophic lifestyle and ecological role in mitigating the impact of chemical fertilization. Functional analyses identify overrepresented genes related to osmotic stress response (synthesis of osmoprotectant compounds, accumulation of potassium ions) and preferential carbon and nitrogen utilization when comparing the microbiome of preserved soils under seasonal changes, reflecting differences in the genetic potential for nutrient cycling and C acquisition in the environment. However, the prevalence of nitrosative stress and denitrification functions in irrigation/fertilization-affected soils of the dry season clearly suggest that nutrient input and disruption of natural water regime may impact biogeochemical cycles linked to the microbial processes, with potential impacts on the ecosystem functionality. These findings help to better understand how natural seasonality and agricultural management differentially affect soil microbial ecology from dry forests, providing support for the development of more sustainable land management in dryland ecosystems.

Characterizing phenol-removing consortia under methanogenic and sulfate-reducing conditions: potential metabolic pathways.

Phenol removal was investigated in anaerobic fixed-structured bed reactors, namely R1 and R2, treating synthetic wastewater simulating the soluble fraction of vinasse under strictly methanogenic (R1) and simultaneous methanogenic/sulfidogenic conditions (R2). Next-generation sequencing (Illumina MiSeq System) was used to further characterize the microbial communities in both systems. Phenol was completely and stably removed in R1 after a short operating period (≈55 days). Conversely, phenol removal in R2 required a longer period for biomass acclimation (≈125 days) to reach levels equivalent to R1. Volatile fatty acids (VFA) accumulation in R2, mainly due to the inhibition of the acetoclastic methanogenesis by sulfide, may have limited phenol removal in the initial operating phases, as intermediate steps from phenol degradation are thermodynamically dependent on the removal of acetate, hydrogen and bicarbonate. Overall, the potential for anaerobically removing phenol from complex wastewaters was confirmed, even at low phenol/COD ratios. 16S rRNA gene sequencing analysis showed a high correlation of taxonomic profile between R1 and the inoculum, whereas a lower correlation was observed between R2 and the inoculum samples. Functional inference further indicated that Syntrophus and Bacillus genera in R1 and Clostridium genus in both reactors possibly played a key-role in phenol degradation.

A membrane aerated biofilm reactor for sulfide control from anaerobically treated wastewater.

A upflow anaerobic sludge blanket reactor was operated combined to a membrane aerated biofilm reactor for sulfate removal and for elemental sulfur reclamation. A commercial silicon tube was used as an oxygen delivery diffuser. The process achieved high rates of sulfide removal from the liquid phase (90%). The hydrogen sulfide removal was influenced by the pH value and at pH value of 7.5, 98% of the H2S was removed. The elemental sulfur was observed inside the membrane, with content in the biomass of 21%. Through the massive sequencing of the samples, the microbial community diversity and the stratification of biomass inside the silicon tube was demonstrated, confirming the presence of sulfide-oxidizing bacteria on the membrane wall. The most important genera found related to the sulfur cycle were Sulfuricurvum, Geovibrio, Flexispira and Sulforospirillum.