Endophytic actinomycetes from medicinal plants produce a wide diversity of secondary metabolites (SM). However, to date, the knowledge about endophytes from Brazil remains scarce. Thus, we analyzed the antimicrobial potential of 10 actinomycetes isolated from the medicinal plant Vochysia divergens located in the Pantanal sul-mato-grossense, an unexplored wetland in Brazil. Strains were classified as belonging to the Aeromicrobium, Actinomadura, Microbacterium, Microbispora, Micrococcus, Sphaerisporangium, Streptomyces, and Williamsia genera, through morphological and 16S rRNA phylogenetic analyzes. A susceptibility analysis demonstrated that the strains were largely resistant to the antibiotics oxacillin and nalidixic acid. Additionally, different culture media (SG and R5A), and temperatures (28 and 36°C) were evaluated to select the best culture conditions to produce the active SM. All conditions were analyzed for active metabolites, and the best antibacterial activity was observed from metabolites produced with SG medium at 36°C. The LGMB491 (close related to Aeromicrobium ponti) extract showed the highest activity against methicillin-resistant Staphylococcus aureus (MRSA), with a MIC of 0.04 mg/mL, and it was selected for SM identification. Strain LGMB491 produced 1-acetyl-β-carboline (1), indole-3-carbaldehyde (2), 3-(hydroxyacetyl)-indole (4), brevianamide F (5), and cyclo-(L-Pro-L-Phe) (6) as major compounds with antibacterial activity. In this study, we add to the knowledge about the endophytic community from the medicinal plant V. divergens and report the isolation of rare actinomycetes that produce highly active metabolites.

Medicinal plants have been recognized as hosts of high diverse endophytic microorganisms, including fungi that produce secondary metabolites with biological activity. Two biomes in Brazil, Pantanal (wetland), and Cerrado (savannah), are known as biodiversity hotspots, and despite their importance as a reservoir for several species, knowledge about the fungal biodiversity in these biomes is very limited. Fungal endophytic communities associated with leaves and petioles of the medicinal plants Vochysia divergens (from Pantanal) and Stryphnodendron adstringens (from Cerrado) were analyzed and studied for their antimicrobial activity against human and plant pathogens. A total of 1,146 isolates of endophytic fungi were obtained from plants collected in January and June of 2016 and grouped into 124 morphotypes. One isolate of each morphotype was identified by sequencing of internal transcribed spacer (ITS) region of the rDNA gene, which revealed the presence of 24 genera, including 3 possible new genera, and 48 taxa. Differences in the endophytic community according to the biomes were observed concerning the analyzed morphotypes. However, when we analyzed the diversity of genera and richness, they were similar for both plants, with Diaporthe, Phyllosticta, and Neofusicoccum as dominant genera. In addition, the community composition of V. divergens differs according to the analyzed plant tissues (petiole and leaf). These data suggested that both, the plant species and plant tissues play a role in the composition of endophytic community. As regards the biotechnological potential, 5 isolates showed activity against the phytopathogens Phyllosticta citricarpa, Colletotrichum abscissum, and Fusarium verticilioides, and 8 isolates showed high activity against clinical pathogens and were selected for the production of crude extract in different culture media. Extract from cultivation of Diaporthe sp. LGMF1548 and LGMF1583 and Neofusicoccum brasiliense LGMF1535 showed activity against methicillin-resistant Staphylococcus aureus, Klebssiella pneumonia, and Candida albicans. In addition, extracts of Diaporthe cf. heveae LGMF1631 inhibited 90% of the mycelial growth of the P. citricarpa and 70% of C. abscissum and may represent an alternative to be used in the biological control of these phytopathogens. Future research will focus on the chemical characterization and structural elucidation of these bioactive compounds.

Brazil has an extraordinary biodiversity, and for many years, has been classified as the first of 17 countries with a mega diversity, with 22% of the total plants in the world (more than 55 000 species). Considering that some endophytes are host-specific, the incomparable plant diversity found in Brazil encompasses an immeasurable variety of habitats and may represent a repository of unexplored species. As a result of the endophyte-host interaction, plant-associated microorganisms have an enormous biosynthetic potential to produce compounds with novelties in structure and bioactivity. Numerous studies have been published over the years describing the endophytic species isolated in Brazil. Identification of these species is generally performed via DNA sequencing. However, many of the genera to which the described taxa belong were reviewed phylogenetically and many species were reclassified. Thus, there is a gap in the real biodiversity of endophytes isolated in Brazil in the last decade. In this scenario, the present study reviewed the biodiversity of endophytes isolated from plants found in different Brazilian biomes from 2012 to 2017, including the following topics: (i) species diversity, (ii) species identification challenges, (iii) biotechnological aspects, and (iv) identified metabolites. Endophytes of 54 species of plants were studied from 2012 to 2017, resulting in the identification of 300 genera, with Diaporthe and Bacillus being the most frequent fungal and bacterial genera, respectively.

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Fungi of the Monilinia genus occur worldwide and affect a wide range of economically important stone fruits. Several Monilinia species are responsible for brown rot. Although this disease is common in Brazil, Monilinia sp. genetic variability in Brazilian orchards has generally been poorly characterized. The present study represents the first report on the genetic diversity of Monilinia sp. from Brazilian orchards. The genetic structure of the Brazilian population was also compared to isolates from other countries, together with some morphological characteristics and aggressiveness. Sixty‐one isolates belonging to the Monilinia genus were obtained from different orchards in Brazilian states. Ten Monilinia fructicola isolates from the United States and one isolate from a fruit imported into Brazil were also evaluated. Phylogenetic analysis of the ITS1‐5.8S‐ITS2 region (internal transcribed spacer) clustered most Brazilian and American isolates with M. fructicola authentic strains from Q‐Bank. Two isolates (one from an imported fruit) clustered as Monilinia laxa. The results revealed M. fructicola as the prevalent species associated with brown rot in Brazilian orchards. To evaluate the intraspecific diversity of M. fructicola and M. laxa, multigene sequence analysis was performed using ITS1‐5.8S‐ITS2 and TEF1 (elongation factor 1). Whilst TEF1 is the most phylogenetically informative gene for intraspecific studies of M. fructicola, RPB2 (RNA polymerase II gene) displayed low variation in intraspecific analysis, but was an informative locus for assigning isolates to M. fructicola or M. laxa species. The amova suggests that Brazilian isolates from the States of the main producing regions belong to a single genetic population, which is genetically distinct from the US (Californian) population of M. fructicola.