Bacteriocin production by Lactobacillus plantarum ST16Pa in supplemented whey powder formulations.

Whey, the main by-product of the dairy industry, is frequently disposed of in the environment without any treatment due to the high cost of this process. Alternatively, whey can be used as a medium to culture lactic acid bacteria and produce value-added products such as bacteriocins. In this work, we attempted to improve bacteriocin production by Lactobacillus plantarum ST16Pa in a whey powder formulation supplemented with additional sources of carbon, nitrogen, and vitamin B12 at different levels and varying the agitation intensity according to a Plackett-Burman experimental design. Only the addition of tryptone positively influenced the production of this bacteriocin. The results allowed us to identify a supplemented whey formulation, comprising 150 g/L of whey total solids plus 10 g/L of tryptone and soybean extract, whose fermentation by Lb. plantarum ST16Pa in shake flasks under agitation at 150 rpm led to a cell-free supernatant with an antimicrobial activity against Listeria innocua 6a CLIST 2865 (inhibition zone of 13.23 mm) close to that previously obtained in de Man, Rogosa and Sharpe medium by other authors. These results are significant considering that the same strain cultured in cheese whey did not previously display any antimicrobial activity.

Correction for Ichiwaki et al., "Genome Sequence of Micromonospora sp. NBS 11-29, an Antibiotic and Hydrolytic Enzyme Producer, Isolated from River Sediment in Brazil".

[This corrects the article DOI: 10.1128/genomeA.00552-17.].

Influence of water quality on diversity and composition of fungal communities in a tropical river.

Freshwater fungi are key decomposers of organic material and play important roles in nutrient cycling, bio-remediation and ecosystem functioning. Although aquatic fungal communities respond to pollution, few studies have quantitatively assessed the effect of freshwater contamination on fungal diversity and composition; and knowledge is scarcer for tropical systems. Here we help fill this knowledge gap by studying a heavily-contaminated South American river spanning a biodiversity hotspot. We collected 30 water samples scattered across a quality gradient over two seasons and analyzed them using Terminal Restriction Fragment Length Polymorphisms (T-RFLP) coupled with 454 Pyrosequencing. Using T-RFLP we identified 451 and 442 Operational Taxonomy Units (OTUs) in the dry and rainy seasons respectively, whereas Pyrosequencing revealed 48,553 OTUs from which 11% were shared between seasons. Although 68% of all identified OTUs and 51% of all identified phyla remained unidentified, dominant fungal phyla included the Ascomycota, Basidiomycota, Chytridiomycota, Glomeromycota, Zygomycota and Neocallimastigomycota, while Calcarisporiella, Didymosphaeria, Mycosphaerella (Ascomycota) and Rhodotorula (Basidiomycota) were the most abundant genera. Fungal diversity was affected by pH and dissolved iron, while community composition was influenced by dissolved oxygen, pH, nitrate, biological oxygen demand, total aluminum, total organic carbon, total iron and seasonality. The presence of potentially pathogenic species was associated with high pH. Furthermore, geographic distance was positively associated with community dissimilarity, suggesting that local conditions allowed divergence among fungal communities. Overall, our findings raise potential concerns for human health and the functioning of tropical river ecosystems and they call for improved water sanitation systems.

Genome Sequence of Micromonospora sp. NBS 11-29, an Antibiotic and Hydrolytic Enzyme Producer, Isolated from River Sediment in Brazil.

The genus Micromonospora comprises actinomycetes with high biotechnological potential, due to their ability to produce secondary metabolites and enzymes. In this study, we report the draft genome sequence of Micromonospora sp. NBS 11-29, which showed antibacterial, cellulolytic, and xylanolytic activities under in vitro conditions.

Screening of polyketide genes from Brazilian Atlantic Forest soil / Evaluación de genes biosintéticos de policétidos provenientes de suelo de la selva atlántica brasileñae / Avaliação de genes biossintéticos de policetídeos provenientes do solo da Mata Atlântica Brasileira

Abstract Soil is a large source of microorganisms with potential to produce bioactive compounds. Since most of them cannot be cultured, metagenomics has become a useful tool in order to evaluate this potential. The aim of this study was to screen biosynthetic polyketide genes (PKS) present in a metagenomic library constructed from a soil sample isolated from the Brazilian Atlantic Forest. The library comprises 5000 clones with DNA inserts between 40 and 50 Kb. The characterization of the biosynthetic gene clusters of these molecules is a promising alternative to elucidate the biotechnological potential of bioactive compounds in microbial communities. The PKS genes were screened using degenerated primers. The positive clones for PKS systems were isolated, and their nucleotide sequences analysed with bioinformatics tools. The screening yielded two positive clones for PKS II genes. Furthermore, variations in the sequences of the PKS II genes from the metagenomic library were observed when compared with sequences of ketosynthases' databases. With these findings we gain insight into the possible relation between new biosynthetic genes and the production of new secondary metabolites.

Resumen El suelo es una fuente importante de microrganismos con potencial para producir compuestos bioactivos. Dado que la gran mayoría de estos microorganismos no puede cultivarse, la metagenómica se ha convertido en una herramienta útil para evaluar dicho potencial. El objetivo del presente estudio fue evaluar los genes biosintéticos de policétidos (PKS) presentes en una biblioteca metagenómica construida a partir de una muestra de suelo aislada de la selva atlántica brasileña. La biblioteca comprende 5000 clones con insertos de DNA entre 40 y 50 Kb. La caracterización de clústeres de genes biosintéticos de estas moléculas es una alternativa promisoria para elucidar el potencial biotecnológico de los compuestos bioactivos en comunidades microbianas. Los genes biosintéticos de PKS se evaluaron usando cebadores degenerados. Se aislaron los clones positivos para sistemas PKS y sus secuencias de nucleótidos se analizaron con herramientas bioinformáticas. La evaluación arrojó dos clones positivos para genes de PKS II. Además, se observaron variaciones en las secuencias de genes de PKS II de la biblioteca metagenómica cuando se compararon con las secuencias de las bases de datos de cetosintasas. Estos hallazgos proporcionan nueva información sobre la posible relación entre nuevos genes biosintéticos y la producción de nuevos metabolitos secundarios.

Resumo O solo é uma fonte de importante de microrganismos com potencial para produzir compostos bioativos. Considerando que a maioria destes microrganismos não se pode cultivar, a metagenômica tem se convertido em uma ferramenta útil para avaliar este potencial. O objetivo deste estudo foi avaliar os genes biossintéticos de policetídeos (PKS) presentes em uma biblioteca metagenômica construída a partir de uma amostra de solo isolada da Mata Atlântica brasileira. A biblioteca compreende 5000 clones com insertos de DNA entre 40 e 50 Kb. A caracterização de clusters de genes biossintéticos destas moléculas é uma alternativa promissora para elucidar o potencial biotecnológico de compostos bioativos em comunidades microbianas. Os genes PKS foram avaliados usando primers degenerados. Os clones positivos para sistemas PKS foram isolados e suas sequências de nucleotídeos foram analisadas com ferramentas de bioinformática. A avaliação forneceu dois clones positivos para genes PKS II. Além disso, variações nas sequências dos genes PKS II da biblioteca metagenômica foram observadas quando comparadas com sequências da base de dados de cetosintases. Com estas descobertas obtivemos uma visão sobre uma possível relação entre novos genes biossintéticos e a produção de novos metabólitos secundários.