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 ST-16Pa in a whey powder formulation supplemented with additional sources of carbon, nitrogen, and vitamin B 12 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.

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.

Sugarcane has great importance in the Brazilian economy because it is raw material for products such as sugar and alcohol. Most cultivars use conventional fertilization and therefore there is a concern in developing alternatives less aggressive to the environment. Alternatives are the organic fertilization and employment diazotrophic endophytic bacteria. The genus Enterobacter has diazotrophic and plant growth promoters representatives. The objective of this study was to analyze the interaction of Enterobacter sp. ICB481 with seedlings of micropropagated sugarcane submitted to organic and conventional fertilization. The seedlings used were divided into three inoculated and three non-inoculated groups: organic, conventional, no fertilization. The parameters evaluated were: leaf length, root volume, fresh and dried leaf and root matters and concentrations of nitrate, ammonium, amino acids, proteins and soluble sugars. The plants were kept in a greenhouse with a photoperiod controlled by two months. After 60 days, it was found that the organic and conventional fertilizers influenced similarly almost all growth parameters and the chlorophyll concentration in both, the inoculated and uninoculated groups. The exception was fresh mass, where the organic treatments promoted greater increase of biomass. There were no differences between organic and conventional groups (with and without bacteria) in the following parameters: leaf length, fresh leaf matter, root and leaf dry matter. The inoculation of Enterobacter promoted increase root volume and fresh mass in organic and conventional groups. Inoculation of the group without fertilization promoted increases in all growth parameters and chlorophyll content as compared to non-inoculated groups. The measurements of nitrate, free amino acids and total proteins content, show the influence of Enterobacter sp. ICB481 the profile of nitrogen content. The concentrations of free ammonium measured were below the detection limit. The protein content of the three inoculated groups did not differ. The conventional groups, inoculated and uninoculated, were not significantly different. The inoculated groups treated with organic fertilization and not fertilized showed higher protein content compared to the same noninoculated. The test showed that colonization Enterobacter sp. ICB481 at 60 days were still present in root tissue and the population was 10 5 CFU g -¹ in the three inoculated groups. The results show beneficial effects promoting plant growth by increasing several growth parameters when as seedlings were inoculated with sugarcane Enterobacter sp. ICB481, particularly under conditions of deficiency of combined nitrogen.

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.

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.

No abstract

No abstract