Caatinga, Amazon and Atlantic Forest as natural sources for microbial lignocellulolytic enzymes.

Brazilian biomes are important sources for environmental microorganisms, including efficient metabolic machineries, like actinomycetes. These bacteria are known for their abilities to produce many bioactive compounds, including enzymes with multiple industrial applications. The present work aimed to evaluate lignocellulolytic abilities of actinomycetes isolated from soil and rhizosphere samples collected at Caatinga, Atlantic and Amazon Forest. Laccase (Lac), lignin peroxidase (LiP), manganese peroxidase (MnP) and cellulase were evaluated for their efficiency. These enzymes have an essential role in lignin decomposition, through oxidation of phenolic and non-phenolic compounds, as well as enzymatic hydrolysis of vegetal biomass. In this sense, a total of 173 actinomycetes were investigated. Eleven (11) of them were selected by their enzymatic performance. The actinomycete AC166 displayed some activity in all analysed scenarios in terms of Lac, MnP and LiP activity, while AC171 was selected as the most promising strain, showing the following activities: 29.7 U.L-1 for Lac; 2.5 U.L-1 for LiP and 23 U.L-1 for MnP. Cellulolytic activities were evaluated at two pH conditions, 4.8 and 7.4, obtaining the following results: 25 U.L-1 and 71 U.L-1, respectively. Thermostability (4, 30 and 60 o C) and salinity concentrations (0 to 4 M) and pH variation (2.0 to 9.0) stabilities of the obtained LiP and Lac enzymatic extracts were also verified. The actinomycete strain AC171 displayed an adaptable response in distinct pH and salt profiles, indicating that bacterial LiP was some halophilic type. Additionally, the strain AC149 produced an alkali and extreme halophilic lignin peroxidase, which are promising profiles for their future application under lignocellulosic biomass at bioethanol biorefineries.

Arbuscular mycorrhizal fungi associated with the rhizosphere of an endemic terrestrial bromeliad and a grass in the Brazilian neotropical dry forest.

Arbuscular mycorrhizal fungi form symbiotic associations with 80-90% of all known plants, allowing the fungi to acquire plant-synthesized carbon, and confer an increased capacity for nutrient uptake by plants, improving tolerance to abiotic and biotic stresses. We aimed at characterizing the mycorrhizal community in the rhizosphere of Neoglaziovia variegata (so-called `caroa`) and Tripogonella spicata (so-called resurrection plant), using high-throughput sequencing of the partial 18S rRNA gene. Both plants are currently undergoing a bioprospecting program to find microbes with the potential of helping plants tolerate water stress. Sampling was carried out in the Caatinga biome, a neotropical dry forest, located in northeastern Brazil. Illumina MiSeq sequencing of 37 rhizosphere samples (19 for N. variegata and 18 for T. spicata) revealed a distinct mycorrhizal community between the studied plants. According to alpha diversity analyses, T. spicata showed the highest richness and diversity based on the Observed ASVs and the Shannon index, respectively. On the other hand, N. variegata showed higher modularity of the mycorrhizal network compared to T. spicata. The four most abundant genera found (higher than 10%) were Glomus, Gigaspora, Acaulospora, and Scutellospora, with Glomus being the most abundant in both plants. Nonetheless, Gigaspora, Diversispora, and Ambispora were found only in the rhizosphere of N. variegata, whilst Scutellospora, Paraglomus, and Archaeospora were exclusive to the rhizosphere of T. spicata. Therefore, the community of arbuscular mycorrhizal fungi of the rhizosphere of each plant encompasses a unique composition, structure and modularity, which can differentially assist them in the hostile environment.

Effect of Monocerin, a Fungal Secondary Metabolite, on Endothelial Cells.

This study reports the isolation and identification of the endophytic fungus Exserohilum rostratum through molecular and morphological analysis using optical and transmission electron microscopy (TEM), as well as the procurement of its secondary metabolite monocerin, an isocoumarin derivative. Considering the previously observed biological activities of monocerin, this study was performed on human umbilical vein endothelial cells (HUVECs) that are widely used as an in vitro model for several different purposes. Important parameters, such as cell viability, senescence-associated ß-galactosidase, cellular proliferation by using 5(6)-carboxyfluorescein diacetate N-succinimidyl ester (CFSE), apoptosis analysis with annexin, cellular morphology through scanning electron microscopy (SEM), and laser confocal analysis were evaluated after exposing the cells to monocerin. After 24 h of exposure to monocerin at 1.25 mM, there was more than 80% of cell viability and a low percentage of cells in the early and late apoptosis and necrosis. Monocerin increased cell proliferation and did not induce cell senescence. Morphological analysis showed cellular integrity. The study demonstrates aspects of the mechanism of action of monocerin on endothelial cell proliferation, suggesting the possibility of its pharmaceutical application, such as in regenerative medicine.

Atlantic Forest's and Caatinga's semiarid soils and their potential as a source for halothermotolerant actinomycetes and proteolytic enzymes.

Actinomycetes are versatile about their metabolism, displaying high capacity to produce bioactive metabolites. Enzymes from actinomycetes represent new opportunities for industrial applications. However, proteases from actinomycetes are poorly described by literature. Thereby, to verify proteolytic potential of actinomycetes, the present study aimed the investigation of bacterial isolates from Caatinga and Atlantic Forest rhizosphere. Fluorescence resonance energy transfer (FRET) peptide libraries were adopted for the evaluations, since they are faster and more qualitative methods, if compared with others described by most reports. A total of 52 microorganisms were inoculated in different culture media (PMB, potato dextrose agar, brain heart infusion agar, Starch Casein Agar and Reasoner's 2A agar), temperatures (12, 20, 30, 37, 45 and 60°C), and saline conditions (0-4 M NaCl), during 7 days. The actinomycetes named as AC 01, 02 and 52 were selected and showed enzymatic abilities under the peptide probes Abz-KLRSSKQ-EDDnp and Abz-KLYSSKQ-EDDnp, achieving enhanced performance at 30 °C. Biochemical parameters were established, showing a predominance of alkaline proteases with activity under saline conditions. Secreted proteases hydrolysed preferentially polar uncharged residues (Y and N) and positively charged groups (R). Phenylmethylsulfonyl fluoride and ethylenediaminetetraacetic acid inhibited the proteins, a characteristic of serine (AC 01 e 02) and metalloproteases (AC 52). All selected strains belonged to Streptomyces genera. In summary, actinomycete strains with halophilic proteolytic abilities were selected, which improve possibilities for their use in detergent formulations, food processing, waste management and industrial bioconversion. It is important to highlight that this is the first report using FRET libraries for proteolytic screening from Caatinga and Atlantic Forest actinobacteria.

Janibacter sp. isolated from deschampsia antarctica rhizosphere as a potential source of antimicrobial compounds

In this study, 106 bacterial strains were isolated from rhizosphere of Deschampsia antarctica and used for the screening of potential antimicrobial compounds. Among all the bacterial strains, 61 (57.55%) were classified as Gram-positive, 34 (32.08%) as Gram-negative, and 11 (10.37%) did not grown under the laboratory culture conditions and were not classified. Organic crude extracts were analysed for potential antimicrobial activity and the B-22-EA ethyl acetate extract was the most effective inhibiting 84% of Escherichia coli growth, and Staphylococcus aureus, Pseudomonas aeruginosa and Micrococcus luteus by 31, 17 and 5%, respectively. The B-22-EA extract showed a MIC of 187 µg/mL on Cryptococcus neoformans, and of 438 µg/mL on Trichophyton rubrum. The strain, coded as B22, was classified as Gram-positive and the taxonomic analysis indicated that this strain belongs to the genera Janibacter, with 98.66% of similarity with Janibacter hoylei PVAS-1 and Janibacter limosus DSM 11140; 98.51% with Janibacter cremeus HR08-44, and 98.36% with Janibacter indicus 0704P10-1, Janibacter anophelis H2.16B and Janibacter terrae CS12. The cellular fatty acids (CFA) composition for B22 (Janibacter sp.) was determined by fatty acid methyl esters (FAME) using gas chromatography and compared with those species for which the B22 strain has a high level of similarity. The comparison among the different species from the genus Janibacter shows that there is a difference in their CFA composition and in their optimum temperature for growth, showing the high biodiversity, even for the same species. The data from this study are important and B-22 (Janibacter sp.) is an interesting source of antimicrobial compounds.

Effect of monocerin, a fungal secondary metabolite, on endothelial cells

This study reports the isolation and identification of the endophytic fungus Exserohilum rostratum through molecular and morphological analysis using optical and transmission electron microscopy (TEM), as well as the procurement of its secondary metabolite monocerin, an isocoumarin derivative. Considering the previously observed biological activities of monocerin, this study was performed on human umbilical vein endothelial cells (HUVECs) that are widely used as an in vitro model for several different purposes. Important parameters, such as cell viability, senescence-associated β-galactosidase, cellular proliferation by using 5(6)-carboxyfluorescein diacetate N-succinimidyl ester (CFSE), apoptosis analysis with annexin, cellular morphology through scanning electron microscopy (SEM), and laser confocal analysis were evaluated after exposing the cells to monocerin. After 24 h of exposure to monocerin at 1.25 mM, there was more than 80% of cell viability and a low percentage of cells in the early and late apoptosis and necrosis. Monocerin increased cell proliferation and did not induce cell senescence. Morphological analysis showed cellular integrity. The study demonstrates aspects of the mechanism of action of monocerin on endothelial cell proliferation, suggesting the possibility of its pharmaceutical application, such as in regenerative medicine.

Rhizobacteria from Brazilian semiarid biome as growth promoters of soybean (Glycine max L.) under low water availability.

Caatinga is the predominant biome in the Brazilian semiarid region. Its vegetation is composed by plants and microorganisms with high tolerance to drought. Microorganisms associated with plants in this biome can develop mechanisms to protect cells from water stress and desiccation. The aim of this study was to identify plant growth-promoting rhizobacteria associated with the drought-tolerant legume Mimosa artemisiana and to examine their effect on the growth of soybean (Glycine max L.) under drought condition (irrigation with 30% of field capacity). Rhizospheric soil was collected along the Caatinga (In the States of Bahia and Pernambuco) at 4 collection points, totaling sixty subsamples. Xerotolerant bacteria with plant growth-promotion characteristics were isolated in a selective culture medium for diazotrophic bacteria. Two strains of the genera Bacillus and one Paenibacillus were promising in in vitro and in vivo tests. Both were able to grow in a medium with low water availability (0.919 Aw) and could produce exopolysaccharides and indole acetic acid (up to 130 µg mL-1). In addition, they produced 1-aminocyclopropane-1-carboxylate (ACC) deaminase and formed biofilms under drought conditions. The inoculation with the isolated strains in the seedling root system mitigated the adverse effects of drought, increasing roots and shoots dry weights of soybean seedlings compared with non-inoculated.

Streptomyces spp. Isolated from Marine and Caatinga Biomes in Brazil for the Biological Control of Duponchelia fovealis.

Actinobacteria have been drawing attention due to their potential for the development of new pest control products. We hereby assess the effects of Streptomyces isolated from marine and caatinga biomes against Duponchelia fovealis Zeller (Lepidoptera: Crambidae), a pest associated with the strawberry culture at a global scale. To this end, eggs deposited by adults were immersed for 5 s in a bacterial suspension, and the larvae were fed on leaflets placed in glass tubes containing bacterial suspensions. In both treatments, the control was a saline solution. The bioassays demonstrated that the Streptomyces strains were able to cause the death of D. fovealis eggs (≈ 40%) and larvae (≈ 65%) compared to untreated eggs (1.4%) and larvae (2.0%). The crude extract of strain T49 and the chitinase extract of strain T26 affected larval growth when applied directly to the thorax of first-instar larvae (larval-adult lifespan of 65.3 ± 0.5 days and 67.5 ± 0.7 days, respectively; survival of 61.2 ± 1.2%) in relation to the control treatment (larval-adult lifespan of 41.75 ± 0.2 days and survival of 83.7 ± 2.6%). The Streptomyces spp. strains T41, T49, and T50 caused antifeeding activity. Apart from larval mortality, the adults that emerged from the larvae exposed to the extracts presented morphological abnormalities, and the moths' chitin spectra showed clear alterations to the pupa and wings. Our studies show, for the very first time, that Streptomyces isolated from the marine environment and the Caatinga biome are effective at provoking the mortality of D. fovealis and are promising agents for developing new products with biological control properties.

Application of extracellular polymers on soil communities exposed to oil and nickel contamination.

The petrochemical industry is responsible for many accidental releases of pollutants in soil such as hydrocarbons and toxic metals. This co-contamination is responsible for a delay in the degradation of the organic pollution. Many successful technologies to remove these metals apply extracellular polymeric substances (EPS). In this study, we tested the application of an EPS from a Paenibacillus sp. to aid the bioremediation of soils contaminated with crude oil and nickel. We conducted a microcosm experiment to soils containing combinations of oil, nickel, and EPS. The final concentration of oil was evaluated with an infrared spectrometer. Also, we sequenced the metagenomes of the samples in an ion torrent sequencer. The application of EPS did not aid the removal of hydrocarbons with or without the presence of nickel. However, it led to a smaller decrease in the diversity indexes. EPS decreased the abundance of Actinobacteria and increased that of Proteobacteria. The EPS also decreased the connectivity among Actinobacteria in the network analysis. The results indicated that the addition of EPS had a higher effect on the community structure than nickel. Altogether, our results indicate that this approach did not aid the bioremediation of hydrocarbons likely due to its effect in the community structure that affected hydrocarbonoclastic microorganisms.

Methanotrophic Community Detected by DNA-SIP at Bertioga's Mangrove Area, Southeast Brazil.

Methanotrophic bacteria can use methane as sole carbon and energy source. Its importance in the environment is related to the mitigation of methane emissions from soil and water to the atmosphere. Brazilian mangroves are highly productive, have potential to methane production, and it is inferred that methanotrophic community is of great importance for this ecosystem. The scope of this study was to investigate the functional and taxonomic diversity of methanotrophic bacteria present in the anthropogenic impacted sediments from Bertioga´s mangrove (SP, Brazil). Sediment sample was cultivated with methane and the microbiota actively involved in methane oxidation was identified by DNA-based stable isotope probing (DNA-SIP) using methane as a labeled substrate. After 4 days (96 h) of incubation and consumption of 0.7 mmol of methane, the most active microorganisms were related to methanotrophs Methylomonas and Methylobacter as well as to methylotrophic Methylotenera, indicating a possible association of these bacterial groups within a methane-derived food chain in the Bertioga mangrove. The abundance of genera Methylomonas, able to couple methane oxidation to nitrate reduction, may indicate that under low dissolved oxygen tensions, some aerobic methanotrophs could shift to intraerobic methane oxidation to avoid oxygen starvation.

Biopolymer production by halotolerant bacteria isolated from Caatinga biome.

Saline environments are extreme habitats with a high diversity of microorganisms source of a myriad of biomolecules. These microorganisms are assigned as extremophiles recognized to be producers of new natural compounds, which can be synthesized by helping to survive under harshness and extreme conditions. In Brazil, in the saline and semi-arid region of Areia Branca (Caatinga biome), halotolerant bacteria (able to growth at high NaCl concentrations) were isolated from rhizosphere of native plants Blutaparon portulacoides and Spergularia sp. and their biopolymer production was studied. A total of 25 bacterial isolates were identified at genus level based on 16S rRNA gene sequence analysis. Isolates were mainly Gram-positive bacteria from Bacillaceae, Staphylococcaceae, Microbacteriaceae, and Bacillales XII incertae sedis families, affiliates to Bacillus, Staphylococcus, Curtobacterium, and Exiguobacterium genera, respectively. One of the Gram-negative isolates was identified as member of the Pseudomonadaceae family, genus Pseudomonas. All the identified strains were halotolerant bacteria with optimum growth at 0.6-2.0 M salt concentrations. Assays for biopolymer production showed that the halotolerant strains are a rich source of compounds as polyhydroxyalkanoates (PHA), biodegradable biopolymer, such as poly(3-hydroxybutyrate) (PHB) produced from low-cost substrates, and exopolysaccharides (EPS), such as hyaluronic acid (HA), metabolite of great interest to the cosmetic and pharmaceutical industry. Also, eight bacterial EPS extracts showed immunostimulatory activity, promising results that can be used in biomedical applications. Overall, our findings demonstrate that these biomolecules can be produced in culture medium with 0.6-2.0 M NaCl concentrations, relevant feature to avoid costly production processes. This is the first report of biopolymer-producing bacteria from a saline region of Caatinga biome that showed important biological activities.

Impact of Inoculation with Pseudomonas aestus CMAA 1215T on the Non-target Resident Bacterial Community in a Saline Rhizosphere Soil.

Plant growth reduction caused by osmotic stress, pathogens, and nutrient scarcity can be overcome by inoculation with plant growth-promoting rhizobacteria (PGPR). Knowing the effects of PGPR on the microbial community beyond those on plant growth can bring new options of soil microbiota management. The present study aimed to investigate the effect of inoculation with the newly described Pseudomonas aestus CMAA 1215T [a 1-aminocyclopropane-1-carboxylate (ACC) deaminase and glycine-betaine producer] on the rhizosphere bacterial community of Zea mays in natural (non-salinized) and saline soil. The bacterial community structure was assessed by sequencing the V6-V7 16S ribosomal RNA using the Ion Personal Genome Machine™. The non-metric multidimensional scaling (NMDS) of the OTU profile (ANOSIM P < 0.01) distinguishes all the treatments (with and without inoculation under saline and natural soils). Inoculated samples shared 1234 OTUs with non-inoculated soil. The most abundant classes in all samples were Alphaproteobacteria, Gammaproteobacteria, Actinobacteria, Acidobacteriia, Bacteroidia, Thermoleophilia, Verrucomicrobiae, Ktenodobacteria, and Bacilli. The inoculation, on the other hand, caused an increase in the abundance of the genera Bacillus, Bryobacter, Bradyrhizobium, "Candidatus Xiphinematobacter", and "Candidatus Udaeobacter" independent of soil salinization. "Candidatus Udaeobacter" has the largest Mean Decrease in Gini Values with higher abundance on inoculated salted soil. In addition, Pseudomonas inoculation reduced the abundance of Gammaproteobacteria and Phycisphaerae. Understanding how inoculation modifies the bacterial community is essential to manage the rhizospheric microbiome to create a multi-inoculant approach and to understand its effects on ecological function.

Actinobacteria from Antarctica as a source for anticancer discovery.

Although many advances have been achieved to treat aggressive tumours, cancer remains a leading cause of death and a public health problem worldwide. Among the main approaches for the discovery of new bioactive agents, the prospect of microbial secondary metabolites represents an effective source for the development of drug leads. In this study, we investigated the actinobacterial diversity associated with an endemic Antarctic species, Deschampsia antarctica, by integrated culture-dependent and culture-independent methods and acknowledged this niche as a reservoir of bioactive strains for the production of antitumour compounds. The 16S rRNA-based analysis showed the predominance of the Actinomycetales order, a well-known group of bioactive metabolite producers belonging to the Actinobacteria phylum. Cultivation techniques were applied, and 72 psychrotolerant Actinobacteria strains belonging to the genera Actinoplanes, Arthrobacter, Kribbella, Mycobacterium, Nocardia, Pilimelia, Pseudarthrobacter, Rhodococcus, Streptacidiphilus, Streptomyces and Tsukamurella were identified. The secondary metabolites were screened, and 17 isolates were identified as promising antitumour compound producers. However, the bio-guided assay showed a pronounced antiproliferative activity for the crude extracts of Streptomyces sp. CMAA 1527 and Streptomyces sp. CMAA 1653. The TGI and LC50 values revealed the potential of these natural products to control the proliferation of breast (MCF-7), glioblastoma (U251), lung/non-small (NCI-H460) and kidney (786-0) human cancer cell lines. Cinerubin B and actinomycin V were the predominant compounds identified in Streptomyces sp. CMAA 1527 and Streptomyces sp. CMAA 1653, respectively. Our results suggest that the rhizosphere of D. antarctica represents a prominent reservoir of bioactive actinobacteria strains and reveals it as an important environment for potential antitumour agents.

Phosphorus-solubilizing Trichoderma spp. from Amazon soils improve soybean plant growth.

Acidic soils rapidly retain applied phosphorus fertilizers and consequently present low availability of this nutrient to plants. The use of phosphate-solubilizing microorganisms to help plant phosphorus (P) absorption is a promising sustainable strategy for managing P deficiencies in agricultural soils. Trichoderma strains have been one of the most studied filamentous fungi for improving the production and development of several crop species mainly due to their capability for symbiotic associations and their ability to control soil-borne plant diseases. Thus, this work sought to bioprospect Trichoderma strains from the Amazon rainforest capable of solubilizing/mineralizing soil phosphate and promoting soybean growth. Soybean plants inoculated with selected Trichoderma strains were cultivated in soil under greenhouse conditions and under a gradient of rock phosphate and triple superphosphate. As a result, 19.5% of the isolated Trichoderma strains were able to solubilize phosphate. In addition, those strains produced different organic acids during the solubilization process. Trichoderma spp. strains showed positive responses in the promotion of soybean growth-from 2.1% to 41.1%-as well as in the efficiency of P uptake-up to 141%. These results reveal the potential of Trichoderma spp. from the Amazon biome as promising biofertilizer agents.

Wheat dwarfing influences selection of the rhizosphere microbiome.

The development of dwarf wheat cultivars combined with high levels of agrochemical inputs during the green revolution resulted in high yielding cropping systems. However, changes in wheat cultivars were made without considering impacts on plant and soil microbe interactions. We studied the effect of these changes on root traits and on the assembly of rhizosphere bacterial communities by comparing eight wheat cultivars ranging from tall to semi-dwarf plants grown under field conditions. Wheat breeding influenced root diameter and specific root length (SRL). Rhizosphere bacterial communities from tall cultivars were distinct from those associated with semi-dwarf cultivars, with higher differential abundance of Actinobacteria, Bacteroidetes and Proteobacteria in tall cultivars, compared with a higher differential abundance of Verrucomicrobia, Planctomycetes and Acidobacteria in semi-dwarf cultivars. Predicted microbial functions were also impacted and network analysis revealed a greater level of connectedness between microbial communities in the tall cultivars relative to semi-dwarf cultivars. Taken together, results suggest that the development of semi-dwarf plants might have affected the ability of plants to recruit and sustain a complex bacterial community network in the rhizosphere.

Beneficial Plant-Associated Microorganisms From Semiarid Regions and Seasonally Dry Environments: A Review.

Semiarid regions are apparently low biodiversity environments; however, these environments may host a phylogenetically diverse microbial community associated with plants. Their microbial inhabitants are often recruited to withstand stressful settings and improve plant growth under harsh conditions. Thus, plant-associated microorganisms isolated from semiarid and seasonally dry environments will be detailed in the present review, focusing on plant growth promotion potential and the microbial ability to alleviate plant abiotic stress. Initially, we explored the role of microbes from dry environments around the world, and then, we focused on seasonally dry Brazilian biomes, the Caatinga and the Cerrado. Cultivable bacteria from semiarid and seasonally dry environments have demonstrated great plant growth promotion traits such as plant hormone production, mobilization of insoluble nutrients, and mechanisms related to plant abiotic stress alleviation. Several of these isolates were able to improve plant growth under stressful conditions commonly present in typical semiarid regions, such as high salinity and drought. Additionally, we highlight the potential of plants highly adapted to seasonal climates from the Caatinga and Cerrado biomes as a suitable pool of microbial inoculants to maintain plant growth under abiotic stress conditions. In general, we point out the potential for the exploitation of new microbial inoculants from plants growing in dry environments to ensure a sustainable increase in agricultural productivity in a future climate change scenario.

Tandem mass spectrometry methods to accelerate the identification of phytotoxic metabolites produced by Streptomyces sp. 39 PL.

Natural products isolated by microorganisms are interesting in the search for new compounds with several biological activities. However, low concentration and structural diversity make the isolation a time-consuming step. Tandem mass spectrometry is a well-established technology for the identification and characterization of target microbial natural products due to high sensitivity and selectivity of these experiments. We developed a method employing neutral loss experiments (LC-ESI-MS/MS) to identify luminacins in microbial crude extracts. The luminacins class exhibited conserved fragmentation pattern with loss at 172 Da relative to glycosides fragment and this loss was used in searching for compounds belonging to this class. Therefore, the crude extract produced by Streptomyces sp. 39 PL was analysed and five luminacins were isolated - one is a novel luminacin I at 466 Da.

Streptomyces rhizosphaericola sp. nov., an actinobacterium isolated from the wheat rhizosphere.

A novel actinobacterium, designated strain 1AS2cT, was isolated from the wheat rhizosphere collected from the Brazilian Cerrado biome. A polyphasic approach, including phenotypic characterization and phylogenetic multilocus sequence analysis (MLSA), was used to determine the taxonomic position of this strain. Analysis of the 16S rRNA gene sequence indicated that the novel strain is closely related to Streptomyces cavourensis NBRC 13026T, Streptomyces albolongus NBRC 13465T and Streptomyces araujoniae ASBV-1T, sharing a similarity value of 98.2, 98.1 and 97.9 %, respectively. Additionally, MLSA of five housekeeping genes (atpD, gyrB, recA, rpoB and trpB) showed evolutionary distances beyond the 0.007 threshold, as well as low DNA-DNA relatedness between strain 1AS2cT and its closest phylogenetic neighbours (S. cavourensis NBRC 13026T, S. albolongus NBRC 13465T and S. araujoniae ASBV-1T: 56, 62.5 and 63.0 %, respectively), indicating a new phylogenetic lineage. The phylogenetic, chemotaxonomic and phenotypic characteristics support the assignment of strain 1AS2cT to the genus Streptomyces, representing a novel species. It is concluded that strain 1AS2cT (=CMAA 1679T=NRRL B-65479T=DSM 105299T) can be classified as the type strain of a novel species of the genus Streptomyces, for which the name Streptomyces rhizosphaericola sp. nov. is proposed.

Functional textiles impregnated with biogenic silver nanoparticles from Bionectria ochroleuca and its antimicrobial activity.

Biogenic silver nanoparticles (AgNPs) were obtained throughout the fungal biosynthesis using extracellular filtrate of the epiphytic fungus B. ochroleuca and were incorporated in cotton and polyester fabrics by common impregnation procedure that was repeated once, twice or four times. Both fabrics were analyzed by scanning electron microscopy (SEM), and the effectiveness of impregnation was determined using inductively coupled plasma optical emission spectrometry (ICP OES). The AgNPs loaded fabrics showed potent antimicrobial activity on Staphylococcus aureus and Escherichia coli as well as on clinically relevant Candida albicans, Candida glabrata, and Candida parapsilosis, indicating that the AgNPs impregnation of cotton and polyester fabrics was efficient. AgNPs effectively inhibited the biofilm formation by Pseudomonas aeruginosa and was not toxic to Galleria mellonella larvae indicating a promising probability of biotechnological application.