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. Moreover, 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 the most abundant genera. Our results suggested that taxonomic and functional profiles investigated were consistent with the harsh environment that photovoltaic panel 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.

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.

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ABSTRACT

Resíduos agroindustriais são ricos em açúcares que podem ser fermentáveis, sendo promissores na geração de produtos de alto valor agregado em processos biotecnológicos. Dentre estes produtos estão os ácidos orgânicos voláteis e álcoois. A fermentação acetona-butanol-etanol (ABE) vem sendo cada vez mais estudada de modo a aumentar a produção dos ácidos e solventes produzidos a partir destas fontes renováveis. Este trabalho teve como objetivo avaliar a produção de solventes e ácidos orgânicos a partir de dois substratos, glicose e água residual do processamento de farinha de mandioca (manipueira). As fermentações ABE em batelada foram realizadas com Clostridium beijerinckii (ATCC 10132)-CB, e três consórcios microbianos previamente submetidos a tratamento térmico, sendo estes o efluente de suinocultura-SM; lodo UASB da estação de tratamento de esgoto-UB; esterco bovino-CM. Enquanto que o inóculo CB obteve maior produção de butanol (1,03 g L-1) e etanol (2,31 g L-1) utilizando a manipueira como fonte de carbono, os demais inóculos exceto UB, produziram maiores quantidades de ácido butírico nas concentrações de 0,31 g L-1 (CM) e 0,13 g L-1 (SM) também com manipueira como fonte de carbono. Outros ácidos orgânicos também foram produzidos nestas fermentações. Os resultados deste estudo mostram a viabilidade do uso da manipueira como fonte de carbono na fermentação ABE para a produção de ácidos e solventes, além de promover uma forma de agregar valor a esses resíduos.