Despite all the benefits assigned to the genetically modified plants, there are still no sufficient data available in literature concerning the possible effects on the microbial communities associated with these plants. Therefore, this study was aimed at examining the effects of the genetic modifications of two transgenic maize genotypes (MON810 – expressing the insecticidal Bt-toxin and TC1507 – expressing the insecticidal Bt-toxin and the herbicide resistance PAT [phosphinothricin-N-acetyltransferase]) on their endophytic microbial communities, in comparison to the microbial community found in the near-isogenic non-transgenic maize (control). The structure of the endophytic communities (Bacteria, Archaea and fungi) and their composition (Bacteria) were evaluated by denaturing gradient gel electrophoresis (DGGE) and the construction of clone libraries, respectively. DGGE analysis and the clone libraries of the bacterial community showed that genotype TC1507 slightly differed from the other two genotypes. Genotype TC1507 showed a higher diversity within its endophytic bacterial community when compared to the other genotypes. Although some bacterial genera were found in all genotypes, such as the genera Burkholderia, Achromobacer and Stenotrophomonas, some were unique to genotype TC1507. Moreover, OTUs associated with Enterobacter predominated only in TC1507 clone libraries. The endophytic bacterial community of the maize genotype TC1507 differed from the communities of the maize genotype MON810 and of their near-isogenic parental genotypes (non-Bt or control). The differences observed among the maize genotypes studied may be associated with insertion of the gene coding for the protein PAT present only in the transgenic genotype TC1507.

The phylum Bacillota comprises metabolically diverse bacteria with potential relevance in several fields. Although some genera, such as Bacillus and others, have been extensively studied, the distribution of Bacillota in the environment is still poorly understood. This study aimed to analyze the distribution of Bacillota present in water and sediment samples from different environments. For this purpose, water (W) and sediment (S) samples were collected from different marine environments (Dois Rios Beach - DR, Abraão Beach - AB, Massambaba Beach – MB, and Guanabara Bay - GB), freshwater lagoons (Jacarepiá Lagoon- JL) and hypersaline lagoons (Vermelha Lagoon - VL), all of which are located in Rio de Janeiro, Brazil. The microbial communities present in each sample were determined by sequencing 16S rRNA-encoding genes. The distribution and diversity of Bacillota were analyzed via QIIME2. The results revealed that Bacillota represented an average of 1% of the microbial community of aquatic microbiomes and were unevenly distributed in aquatic water and sediment. The highest abundances of Bacillota were detected in JL_S and VL_S, and the lowest abundances were observed in MB_W and AB_W. Only sequences related to the Bacilli and Clostridia classes were identified. The main Bacillota genera identified were Bacillus and an unidentified Clostridiales order genus. The VL_S and JL_S samples had the highest numbers of exclusive Bacillota genera. On the other hand, 15 Bacillota genera, which are generally observed in the human and animal guts, were found only in anthropogenically impacted GB_W and AB_W. The obtained results revealed how Bacillota are distributed in different aquatic environments.

Biosurfactants are surface-active biomolecules with great applicability in the food, pharmaceutical and oil industries. Endospore-forming bacteria, which survive for long periods in harsh environments, are described as biosurfactant producers. Although the ubiquity of endospore-forming bacteria in saline and hypersaline environments is well known, studies on the diversity of the endospore-forming and biosurfactant-producing bacterial genera/species in these habitats are underrepresented. In this study, the structure of endospore-forming bacterial communities in sediment/mud samples from Vermelha Lagoon, Massambaba, Dois Rios and Abraão Beaches (saline environments), as well as the Praia Seca salterns (hypersaline environments) was determined via denaturing gradient gel electrophoresis. Bacterial strains were isolated from these environmental samples and further identified using 16S rRNA gene sequencing. Strains presenting emulsification values higher than 30 % were grouped via BOX-PCR, and the culture supernatants of representative strains were subjected to high temperatures and to the presence of up to 20 % NaCl to test their emulsifying activities in these extreme conditions. Mass spectrometry analysis was used to demonstrate the presence of surfactin. A diverse endospore-forming bacterial community was observed in all environments. The 110 bacterial strains isolated from these environmental samples were molecularly identified as belonging to the genera Bacillus, Thalassobacillus, Halobacillus, Paenibacillus, Fictibacillus and Paenisporosarcina. Fifty-two strains showed emulsification values of at least 30%, and they were grouped into18 BOX groups. The stability of the emulsification values varied when the culture supernatants of representative strains were subjected to high temperatures and to the presence of up to 20% NaCl. The presence of surfactin was demonstrated in one of the most promising strains. The environments studied can harbor endospore-forming bacteria capable of producing biosurfactants with biotechnological applications. Various endospore-forming bacterial genera/species are presented for the first time as biosurfactant producers.