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Microbial community structure and dynamics in thermophilic composting viewed through metagenomics and metatranscriptomics
Composting is a promising source of new organisms and thermostable enzymes that may be helpful in environmental management and industrial processes. Here we present results of metagenomicand metatranscriptomic-based analyses of a large composting operation in the Sao Paulo Zoo Park. This composting exhibits a sustained thermophilic profile (50°C to 75°C), which seems to preclude fungal activity. The main novelty of our study is the combination of time-series sampling with shotgun DNA, 16S rRNA gene amplicon, and metatranscriptome high-throughput sequencing, enabling an unprecedented detailed view of microbial community structure, dynamics, and function in this ecosystem. The time-series data showed that the turning procedure has a strong impact on the compost microbiota, restoring to a certain extent the population profile seen at the beginning of the process; and that lignocellulosic biomass deconstruction occurs synergistically and sequentially, with hemicellulose being degraded preferentially to cellulose and lignin. Moreover, our sequencing data allowed near-complete genome reconstruction of five bacterial species previously found in biomassdegrading environments and of a novel biodegrading bacterial species, likely a new genus in the order Bacillales. The data and analyses provided are a rich source for additional investigations of thermophilic composting microbiology.
Cellulolytic and proteolytic ability of bacteria isolated from gastrointestinal tract and composting of a hippopotamus
The bioprospection for cellulase and protease producers is a promise strategy for the discovery of potential biocatalysts for use in hydrolysis of lignocellulosic materials as well as proteic residues. These enzymes can increment and turn viable the production of second generation ethanol from different and alternative sources. In this context, the goal of this study was the investigation of cellulolytic and proteolytic abilities of bacteria isolated from the gastrointestinal tract of a hippopotamus as well as from its composting process. It is important to highlight that hippopotamus gastrointestinal samples were a non-typical sources of efficient hydrolytic bacteria with potential for application in biotechnological industries, like biofuel production. Looking for this, a total of 159 bacteria were isolated, which were submitted to qualitative and quantitative enzymatic assays. Proteolytic analyzes were conducted through the evaluation of fluorescent probes. Qualitative assays for cellulolytic abilities revealed 70 positive hits. After quantitative analyzes, 44 % of these positive hits were selected, but five (5) strains showed cellulolytic activity up to 11,8 FPU/ mL. Regarding to proteolytic activities, six (6) strains showed activity above 10 %, which overpassed results described in the literature. Molecular analyzes based on the identification of 16S rDNA, revealed that all the selected bacterial isolates were affiliated to Bacillus genus. In summary, these results strongly indicate that the isolated bacteria from a hippopotamus can be a potential source of interesting biocatalysts with cellulolytic and proteolytic activities, with relevance for industrial applications.
Application of Conventional Heating and Microwave Irradiation for the Biocatalytic Reduction of Fluoroacetophenones by Thermophilic Bacteria
This paper describes the bioreduction of four fluoroacetophenones with thermophilic bacteria (Bacillus sp. FPZSP005, B. subtilis FPZSP088, B. licheniformis FPZSP055 and BC-FPZSP051). The reduction reactions were performed under microwave irradiation and the thermophilic bacteria of the Bacillus genus provided moderate conversions to fluoroalcohols with yields in the 26-42% ranges and 5-62% e.e. When the reactions were carried out under conventional heating, they showed high conversions and selectivities (up to > 99% e.e.). This is the first study in the literature on the use of microwave irradiation with thermophilic bacteria applied on biocatalysis.