Insights of energy potential in thermophilic sugarcane vinasse and molasses treatment: does two-stage codigestion enhance operational performance?

The study evaluated the performance of thermophilic co-digestion in both single-stage methanogenic reactors (TMR) and two-stage systems, consisting of a thermophilic acidogenic reactor and a thermophilic sequential methanogenic reactor (TSMR). A 1:1 mixture of sugarcane vinasse and molasses was codigested in anaerobic fluidized bed reactors, with varying organic matter concentrations based on chemical oxygen demand (COD) ranging from 5 to 22.5 g COD L-1. Both systems achieved high organic matter removal efficiency (51 to 86.5%) and similar methane (CH4) yields (> 148 mL CH4 g-1CODremoved). However, at the highest substrate concentration (22.5 g COD L-1), the TSMR outperformed the TMR in terms of energy generation potential (205.6 kJ d-1 vs. 125 kJ d-1). Phase separation in the two-stage system increased bioenergy generation by up to 43.5% at lower substrate concentrations (7.5 g COD L-1), with hydrogen (H2) generation playing a critical role in this enhancement. Additionally, the two-stage system produced value-added products, including ethanol (2.3 g L-1), volatile organic acids (3.2 g lactate L-1), and H2 (0.6-2.7 L H2 L-1 d-1). Microbial analysis revealed that Thermoanaerobacterium, Caldanaerobius, and Clostridium were dominant at 5 g COD L-1, while Lactobacillus prevailed at concentrations of ≥ 15 g COD L-1. The primary methane producers in the single-stage system were Methanosarcina, Methanoculleus, and Methanobacterium, whereas Methanothermobacter, Bathyarchaeia, and Methanosarcina dominated in the two-stage system.

Harnessing the Energy Potential and Value-Added Products from the Treatment of Sugarcane Vinasse: Maximizing Methane Production Through Co-Digestion with Sugarcane Molasses and Enhanced Organic Loading.

This study assessed the impact of organic loading rate (OLR) on methane (CH4) production in the anaerobic co-digestion (AcoD) of sugarcane vinasse and molasses (SVM) (1:1 ratio) within a thermophilic fluidized bed reactor (AFBR). The OLR ranged from 5 to 27.5 kg COD.m-3.d-1, with a fixed hydraulic retention time (HRT) of 24 h. Organic matter removal varied from 56 to 84%, peaking at an OLR of 5 kg COD.m-3.d-1. Maximum CH4 yield (MY) (272.6 mL CH4.g-1CODrem) occurred at an OLR of 7.5 kg COD.m-3.d-1, while the highest CH4 production rate (MPR) (4.0 L CH4.L-1.d-1) and energy potential (E.P.) (250.5 kJ.d-1) were observed at an OLR of 20 kg COD.m-3.d-1. The AFBR exhibited stability across all OLR. At 22.5 kg COD.m-3.d-1, a decrease in MY indicated methanogenesis imbalance and inhibitory organic compound accumulation. OLR influenced microbial populations, with Firmicutes and Thermotogota constituting 43.9% at 7.5 kg COD.m-3.d-1, and Firmicutes dominating (52.7%) at 27.5 kg COD.m-3.d-1. Methanosarcina (38.9%) and hydrogenotrophic Methanothermobacter (37.6%) were the prevalent archaea at 7.5 kg COD.m-3.d-1 and 27.5 kg COD.m-3.d-1, respectively. Therefore, this study demonstrates that the organic loading rate significantly influences the efficiency of methane production and the stability of microbial communities during the anaerobic co-digestion of sugarcane vinasse and molasses, indicating that optimized conditions can maximize energy yield and maintain methanogenic balance.

Towards a circular bioeconomy to produce methane by co-digestion of coffee and brewery waste using a mixture of anaerobic granular sludge and cattle manure as inoculum.

Coffee processing wastes, such as solid (pulp and husk) and wastewater, co-digested with industrial brewery wastewater, serve as excellent substrates for generating methane in the anaerobic digestion process. This study compared methane production using different compositions of cattle manure (CM) and granular sludge from an Upflow Anaerobic Sludge Blanket (UASB) reactor used in poultry wastewater treatment (GS). Four anaerobic batch reactors (500 mL) were assembled, A (50% CM and 50% GS), B (60% CM and 40% GS), C (70% CM and 30% of GS) and D (60% CM and 40% GS). Equal concentrations of substrates were added to all reactors: pulp and husk pretreated by hydrothermolysis (1 g L-1), coffee (10 g COD L-1) and brewery (1.5 g COD L-1) wastewaters. Assays A, B and C were supplemented with 2 g L-1 of yeast extract, except for assay D. The reactors were operated at 37 °C and pH 7.0. In assay B, the highest CH4 production of 759.15 ± 19.20 mL CH4 g-1 TS was observed, possibly favored by the synergistic interactions between cellulolytic bacteria Christensenellaceae_R-7_group and Methanosaeta archaea, as inferred by genes encoding enzymes related to acetoclastic methanogenesis (acetyl-CoA synthetase). Consequently, the electricity production potential of assay B (45614.08 kWh-1 year-1) could meet the energy demand of a farm producing coffee and beer, contributing to a positive energy balance concerning methane generation.

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 diversity and metabolic inference of diclofenac removal in optimised batch heterotrophic-denitrifying conditions by means of factorial design.

Using the Response Surface Methodology (RSM) and Rotational Central Composite Design (RCCD), this study evaluated the removal of DCF under denitrifying conditions, with ethanol as cosubstrate, in batch reactors, being 1 L Erlenmeyer flasks (330 mL of reactional volume) containing Dofing medium and kept under agitation at 130 rpm and incubated at mesophilic temperature (30 °C). It considered the individual and multiple effects of the variables: nitrate (130 - 230 mg NO3- L-1), DCF (60-100 µg DCF L-1) and ethanol (130 - 230 mg EtOH L-1). The highest drug removal efficiency (17.5%) and total nitrate removal were obtained at 176.6 ± 4.3 mg NO3 -L-1, 76.8 ± 3.7 µg DCF L-1, and 180.0 ± 2.5 mg EtOH L-1. Under such conditions, the addition of ethanol and nitrate was significant for the additional removal of diclofenac (p > 0.05). The prevalence of Rhodanobacter, Haliangium and Terrimonas in the inoculum biomass (activated sludge systems) was identified through the 16S rRNA gene sequencing. The potential of these genera to remove nitrate and degrade diclofenac was inferred, and the main enzymes potentially involved in this process were α-methylacyl-CoA racemase, long-chain fatty acid-CoA ligase, catalases and pseudoperoxidases.

Potential methanogenic and degradation of nonylphenol ethoxylate from domestic sewage: unravelling the essential roles of nutritional conditions and microbial community.

Nonylphenol ethoxylathe (NPEO) is a non-ionic surfactant of increasing concern, used in the formulation of laundry detergents and is frequently found in aquatic environments. The purpose of this study was to evaluate the effects of yeast extract (YE) and sodium fumarate (SF) in NPEO removal from domestic sewage under anaerobic conditions via central composite rotatable design (CCRD) and response surface methodology (RSM). Experiments were designed by varying concentrations of NPEO (1.6-5.8 mg L-1), YE (131.8-468.2 mg L-1) and SF (97.7-602.3 mg L-1) in batch reactors. SF and YE addition significantly influenced NPEO removal and CH4 production. Optimal values of YE (400 mg L-1) and SF (200 mg L-1) result in removal efficiency of 97% for 5 mg L-1 of NPEO, being mostly removed by biodegradation (86%). Meanwhile COD removal was 95% and methane yield was 134 ± 4 NmLCH4 g-¹CODremoved. The most abundant Bacteria genus identified were Macellibacteroides, Longilinea, Petrimonas and Proteiniphilum, while for Archaea, Methanosaeta and Methanoregula were the genera identified in higher relative abundances in optimized conditions.

Biomethane recovery through co-digestion of cheese whey and glycerol in a two-stage anaerobic fluidized bed reactor: Effect of temperature and organic loading rate on methanogenesis.

Anaerobic digestion for CH4 recovery in wastewater treatment has been carried out with different strategies to increase process efficiency, among which co-digestion and the two-stage process can be highlighted. In this context, this study aimed at evaluating the co-digestion of cheese whey and glycerol in a two-stage process using fluidized bed reactors, verifying the effect of increasing the organic loading rate (OLR) (2-20 g-COD.L-1.d-1) and temperature (thermophilic and mesophilic) in the second stage methanogenic reactor. The mesophilic methanogenic reactor (R-Meso) (mean temperature of 22 °C) was more tolerant to high OLR and its best performance was at 20 g-COD.L-1.d-1, resulting in methane yield (MY) and methane production (MPR) of 273 mL-CH4.g-COD-1 and 5.8 L-CH4.L-1.d-1 (with 67% of CH4), respectively. Through 16S rRNA gene massive sequencing analysis, a greater diversity of microorganisms was identified in R-Meso than in R-Thermo (second stage methanogenic reactor, 55 °C). Firmicutes was the phyla with higher relative abundance in R-Thermo, while in R-Meso the most abundant ones were Proteobacteria and Bacteroidetes. Regarding the Archaea domain, a predominance of hydrogenotrophic microorganisms could be observed, being the genera Methanothermobacter and Methanobacterium the most abundant in R-Thermo and R-Meso, respectively. The two-stage system composed with a thermophilic acidogenic reactor + R-Meso was more adequate for the co-digestion of cheese whey and glycerol than the single-stage process, promoting increases of up to 47% in the energetic yield (10.3 kJ.kg-COD-1) and 14% in organic matter removal (90.5%).

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.

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.

Removal of nonylphenol ethoxylate surfactant in batch reactors: emphasis on methanogenic potential and microbial community characterization under optimized conditions.

ABSTRACTNonylphenol ethoxylate (NPE) is an endocrine-disrupting chemical that has bioaccumulative, persistent and toxic characteristics in different environmental matrices and is difficult to remove in sewage treatment plants. In this study, the effects of the initial concentration of NPE (0.2 ± 0.03 - 3.0 ± 0.02 mg. L-1) and ethanol (73.9 ± 5.0-218.6 ± 10.6 mg. L-1) were investigated using factorial design. Assays were carried out in anaerobic batch reactors, using the Zinder basal medium, yeast extract (200 mg. L-1), vitamin solution and sodium bicarbonate (10% v/v). The optimal conditions were 218.56 mg.L-1 of ethanol and 1596.51 µg.L-1 of NPE, with 92% and 88% of NPE and organic matter removal, respectively, and methane yield (1689.8 ± 59.6 mmol) after 450 h of operation. In this condition, bacteria potentially involved in the degradation of this surfactant were identified in greater relative abundance, such as Acetoanaerobium (1.68%), Smithella (1.52%), Aminivibrio (0.91%), Petrimonas (0.57%) and Enterobacter (0.47%), as well as archaea Methanobacterium and Methanoregula, mainly involved in hydrogenotrophic pathway.

[Analysis of the coverage of supply and of the water quality distributed in different regions of Brazil in 2019]. / Análise da cobertura de abastecimento e da qualidade da água distribuída em diferentes regiões do Brasil no ano de 2019.

Bearing in mind that universal access to sanitation services is one of the objectives of the Brazilian Plan for Basic Sanitation and one of the sustainable development goals (SDG), this research sought to evaluate the coverage of supply and of the quality of water distributed in Brazil in 2019. Data from the National Sanitation Information System (SNIS) and Water Quality for Human Consumption Surveillance Information System (Sisagua) databases were evaluated. It was found that 82% of the population has access to Water Supply Systems (WSS), this percentage only being lower in the North (58%) and Northeast (74%) regions. Most of the population is served by WSS; however, in the North region, 6.6% of the population is served by WSS and 7.2% by Collective Alternative Solution (CAS) without treatment. For the Total Coliforms parameter, 21.9% of CAS samples from the North region were outside the potability standard, while for the residual disinfectant agent, 40.6% of WSS from the Northeast region was outside this standard (with 19% of the samples having a concentration of the disinfectant agent above 5.0 mg/L, and 81% of the samples presenting concentration lower than 0.2 mg/L. The conclusion drawn is that part of the population may be vulnerable to water quality-related risks.

Tendo em vista que a universalização dos serviços de saneamento é uma das metas do Plano Nacional de Saneamento Básico (PLANSAB) e um dos objetivos de desenvolvimento sustentável (ODS), esta pesquisa objetivou-se avaliar a cobertura do abastecimento e a qualidade da água distribuída no Brasil em 2019. Foram utilizados os dados do Sistema Nacional de Informações sobre Saneamento (SNIS) e do Sistema de Informação de Vigilância da Qualidade da Água para Consumo Humano (Sisagua). Verificou-se que 82% da população foi atendida por serviços de água, sendo este percentual ainda menor considerando apenas a região Norte (58%) e Nordeste (74%). A maioria da população é atendida por Sistemas de Abastecimento de Água (SAA); entretanto, na região Norte, 6,6% da população é atendida por SAA e 7,2% por Solução Alternativa Coletiva (SAC) sem tratamentos. Para o parâmetro Coliformes totais, 21,9% das amostras de SAC da região Norte estavam fora do padrão de potabilidade, enquanto para o residual de agente desinfetante, 40,6% de SAA da região Nordeste encontravam-se fora do padrão, sendo que deste total 19% das amostras apresentavam concentração do agente desinfetante acima de 5,0 mg/L e 81% das amostras apresentavam concentrações menores que 0,2 mg/L. Conclui-se que parte da população pode estar vulnerável aos riscos relacionados à qualidade da água.

Análise da cobertura de abastecimento e da qualidade da água distribuída em diferentes regiões do Brasil no ano de 2019 / Analysis of the coverage of supply and of the water quality distributed in different regions of Brazil in 2019

Resumo Tendo em vista que a universalização dos serviços de saneamento é uma das metas do Plano Nacional de Saneamento Básico (PLANSAB) e um dos objetivos de desenvolvimento sustentável (ODS), esta pesquisa objetivou-se avaliar a cobertura do abastecimento e a qualidade da água distribuída no Brasil em 2019. Foram utilizados os dados do Sistema Nacional de Informações sobre Saneamento (SNIS) e do Sistema de Informação de Vigilância da Qualidade da Água para Consumo Humano (Sisagua). Verificou-se que 82% da população foi atendida por serviços de água, sendo este percentual ainda menor considerando apenas a região Norte (58%) e Nordeste (74%). A maioria da população é atendida por Sistemas de Abastecimento de Água (SAA); entretanto, na região Norte, 6,6% da população é atendida por SAA e 7,2% por Solução Alternativa Coletiva (SAC) sem tratamentos. Para o parâmetro Coliformes totais, 21,9% das amostras de SAC da região Norte estavam fora do padrão de potabilidade, enquanto para o residual de agente desinfetante, 40,6% de SAA da região Nordeste encontravam-se fora do padrão, sendo que deste total 19% das amostras apresentavam concentração do agente desinfetante acima de 5,0 mg/L e 81% das amostras apresentavam concentrações menores que 0,2 mg/L. Conclui-se que parte da população pode estar vulnerável aos riscos relacionados à qualidade da água.

Abstract Bearing in mind that universal access to sanitation services is one of the objectives of the Brazilian Plan for Basic Sanitation and one of the sustainable development goals (SDG), this research sought to evaluate the coverage of supply and of the quality of water distributed in Brazil in 2019. Data from the National Sanitation Information System (SNIS) and Water Quality for Human Consumption Surveillance Information System (Sisagua) databases were evaluated. It was found that 82% of the population has access to Water Supply Systems (WSS), this percentage only being lower in the North (58%) and Northeast (74%) regions. Most of the population is served by WSS; however, in the North region, 6.6% of the population is served by WSS and 7.2% by Collective Alternative Solution (CAS) without treatment. For the Total Coliforms parameter, 21.9% of CAS samples from the North region were outside the potability standard, while for the residual disinfectant agent, 40.6% of WSS from the Northeast region was outside this standard (with 19% of the samples having a concentration of the disinfectant agent above 5.0 mg/L, and 81% of the samples presenting concentration lower than 0.2 mg/L. The conclusion drawn is that part of the population may be vulnerable to water quality-related risks.

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.

Characterization of biosurfactant from yeast using residual soybean oil under acidic conditions and their use in metal removal processes.

This study aimed at the production of biosurfactants from yeasts under acidic conditions using residual soybean oil as a carbon source, as well as the biosurfactant produced in the solubilization of metals in sewage sludge. The yeast Meyerozyma guilliermondii was considered the best producer in both pH 4.0 and 2.0; therefore, the product obtained by this yeast was characterized by Fourier transform infrared (FT-IR) and 1H nuclear magnetic resonance (NMR) spectroscopy. Moreover, it was applied in metal removal assays in anaerobic sewage sludge. The spectra obtained in FT-IR suggested that M. guilliermondii's biosurfactant had a similar structure to glycolipids from the sophorolipid class, and it was confirmed by 1H NMR spectroscopy. In the bioleaching assays, the application of biosurfactant (2%) produced by M. guilliermondii with pH adjusted to 2.0 was able to solubilize 15.9% of cadmium from the sewage sludge.

Bioleaching of toxic metals from sewage sludge by co-inoculation of Acidithiobacillus and the biosurfactant-producing yeast Meyerozyma guilliermondii.

The aim of this research is to evaluate the influence of co-inoculation of Acidithiobacillus bacteria and the biosurfactant-producing yeast Meyerozyma guilliermondii in bioleaching processes. The tests were carried out using sewage sludge from UASB reactors co-inoculated with cultures of Acidithiobacillus and M. guilliermondii to promote the solubilization of Cd, Cr, Cu, Ni, Pb and Zn which were determined by Inductively Coupled Plasma - Optical Emission Spectrometry (ICP- OES). After 10 days of incubation, 76.5% of Zn, 59.8% of Ni, 22.0% of Cu, 9.8% of Cd, 9.8% Cr and 7.1% of Pb were solubilized. It was observed that the presence of yeast accelerated the time required for Cd solubilization from 240 to 96 h and there was a 20.1% reduction in nitrogen concentration and 7.6% for phosphorus in this assay. After the bioleaching and co-inoculation assays, the product obtained reached the maximum permissible concentrations for soil disposal for all the analyzed metals in the State of São Paulo, United States and also European Community standards.

A comparison between cactophilic yeast communities isolated from Cereus hildmannianus and Praecereus euchlorus necrotic cladodes.

In the cactus-yeast-Drosophila model system, the necrotic cladode is used as substrate by a diverse and specific microbiota, which is utilized as food source by Drosophila. Although this association has been the focus of many studies in arid regions of North America, little is known of its composition in South America. This study analysed yeast communities isolated from two South American cacti species: Cereus hildmannianus and Praecereus euchlorus. Fourteen yeast species were isolated and identified by their morpho-physiological character and partial rRNA gene sequencing. Arthropods hatched from the analysed cladodes were identified. There was little similarity between the isolated yeast communities either in terms of cacti species (S = 0.286) or collection sites (S = 0.214-0.335). To the best of the authors' knowledge, this is the first time that Metschnikowia koreensis and Hannaella sinensis have been described in association with cacti. Also, Drosophila buzzatti has not been described in association with Praecereus. The similarity between cactophilic arthropod communities found in the different cacti was low (S = 0.266) and zero when only Drosophila was considered. These results suggest that exploration by Drosophila species is the main factor that drives low yeast community similarity between cacti species.