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.

Interferences that impact measuring optimal L-asparaginase activity and consequent errors interpreting these data.

L-asparaginase is an enzyme produced by microorganisms, plants, and animals, which is used clinically for the treatment for acute lymphoblastic leukemia (ALL) and, in the food industry, to control acrylamide formation in baked foods. The purpose of this review was to evaluate the available literature regarding microbial sources of L-asparaginase, culture media used to achieve maximum enzyme expression in microbial fermentations, and assay methods employed to assess L-asparaginase activity. Studies were gathered by searching PubMed, and Web of Science databases before January 22, 2018, with no time restrictions. The articles were evaluated according to the source of L-asparaginase being studied, the nitrogen source in the culture medium, the type of sample, and the method employed to evaluate L-asparaginase activity. Bacterial L-asparaginase appeared to be the most commonly studied source of the enzyme and, most often, the enzyme activity was assayed from crude protein extracts using the Nessler method, which is an indirect measurement of asparaginase activity that determines the concentration of ammonia generated after the action of the enzyme on the substrate, L-asparagine. However, ammonia is also generated throughout microbial fermentations and this endogenous ammonia will also reduce the Nessler reagent if crude microbial extracts are used to determine total L-asparaginase activity. We suggest that current estimates of L-asparaginase activity reported in the literature may be overestimated when Nessler reagent is used, since we were unable to find a single study that made reference to the possible inference of fermentation derived ammonia.

Rhodococcus psychrotolerans sp. nov., isolated from rhizosphere of Deschampsia antarctica.

A novel actinobacterium, designated strain CMAA 1533T, was isolated from the rhizosphere of Deschampsia antarctica collected at King George Island, Antarctic Peninsula. Strain CMAA 1533T was found to grow over a wide range of temperatures (4-28 °C) and pH (4-10). Macroscopically, the colonies were observed to be circular shaped, smooth, brittle and opaque-cream on most of the culture media tested. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CMAA 1533T belongs to the family Nocardiaceae and forms a distinct phyletic line within the genus Rhodococcus. Sequence similarity calculations indicated that the novel strain is closely related to Rhodococcus degradans CCM 4446T, Rhodococcus erythropolis NBRC 15567T and Rhodococcus triatomae DSM 44892T (≤ 96.9%). The organism was found to contain meso-diaminopimelic acid, galactose and arabinose in whole cell hydrolysates. Its predominant isoprenologue was identified as MK-8(H2) and the polar lipids as diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannosides. The major fatty acids were identified as Summed feature (C16:1 ω6c and/or C16:1 ω7c), C16:0, C18:1 ω9c and 10-methyl C18:0. The G+C content of genomic DNA was determined to be 65.5 mol%. Unlike the closely related type strains, CMAA 1533T can grow at 4 °C but not at 37 °C and was able to utilise adonitol and galactose as sole carbon sources. Based on phylogenetic, chemotaxonomic and physiological data, it is concluded that strain CMAA 1533T (= NRRL B-65465T = DSM 104532T) represents a new species of the genus Rhodococcus, for which the name Rhodococcus psychrotolerans sp. nov. is proposed.

Pseudomonas aestus sp. nov., a plant growth-promoting bacterium isolated from mangrove sediments.

Strain CMAA 1215T, a Gram-reaction-negative, aerobic, catalase positive, polarly flagellated, motile, rod-shaped (0.5-0.8 × 1.3-1.9 µm) bacterium, was isolated from mangrove sediments, Cananéia Island, Brazil. Analysis of the 16S rRNA gene sequences showed that strain CMAA 1215T forms a distinct phyletic line within the Pseudomonas putida subclade, being closely related to P. plecoglossicida ATCC 700383T, P. monteilii NBRC 103158T, and P. taiwanensis BCRC 17751T of sequence similarity of 98.86, 98.73, and 98.71%, respectively. Genomic comparisons of the strain CMAA 1215T with its closest phylogenetic type strains using average nucleotide index (ANI) and DNA:DNA relatedness approaches revealed 84.3-85.3% and 56.0-63.0%, respectively. A multilocus sequence analysis (MLSA) performed concatenating 16S rRNA, gyrB and rpoB gene sequences from the novel species was related with Pseudomonas putida subcluster and formed a new phylogenetic lineage. The phenotypic, physiological, biochemical, and genetic characteristics support the assignment of CMAA 1215T to the genus Pseudomonas, representing a novel species. The name Pseudomonas aestus sp.nov. is proposed, with CMAA 1215T (=NRRL B-653100T = CBMAI 1962T) as the type strain.

Elicitation of Streptomyces lunalinharesii secondary metabolism through co-cultivation with Rhizoctonia solani.

The concern regarding the emergence of phytopathogens strains which are resistant to conventional agrochemicals has given support to the search for alternatives on the use of chemical pesticides in agriculture. In this context, microorganisms are considered as promising sources of useful natural compounds and actinobacteria are particularly relevant since they are known to produce several bioactive metabolites. The objective of this work was to investigate the production of secondary metabolites with antifungal activity by a strain of the actinobacteria Streptomyces lunalinharesii (A54A) under axenic conditions and in co-cultivation with the phytopathogen Rhizoctonia solani. Tests to evaluate antifungal activity of the extracts indicated the presence of diffusable molecules capable of inhibiting the growth of R. solani produced by S. lunalinharesii, especially when in the presence of the fungus during fermentation. Metabolomic analyzes allowed the putative annotation of the bioactive compounds desferrioxamine E and anisomycin, in addition to the evaluation of the metabolic profile of the isolate when grown in axenic mode and in co-cultivation, while statistical analyzes enabled the comparison of such profiles and the identification of metabolites produced in greater relative quantities in the elicitation condition. Such methodologies provided the selection of unknown features with high bioactive potential for dereplication, and several metabolites of S. lunalinharesii possibly represent novel compounds.

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.

Genome Sequence of Streptomyces cavourensis 1AS2a, a Rhizobacterium Isolated from the Brazilian Cerrado Biome.

Streptomyces cavourensis strain 1AS2a, isolated from wheat rhizosphere in the Brazilian Neotropical savanna, exhibits strong antimicrobial activities. Its genome comprises 7,600,475 bp with 6,590 open reading frames (ORFs) that reveal 30 biosynthetic gene clusters (BGCs). It provides a genetic basis for further research of the potential of this strain for the production of antimicrobial compounds.

Draft Genome Sequence of Plant Growth-Promoting Drought-Tolerant Bacillus sp. Strain CMAA 1363 Isolated from the Brazilian Caatinga Biome.

The strain of Bacillus sp. CMAA 1363 was isolated from the Brazilian Caatinga biome and showed plant growth-promoting traits and ability to promote maize growth under drought stress. Sequencing revealed genes involved in stress response and plant growth promotion. These genomic features might aid in the protection of plants against the negative effects imposed by drought.

Genome Sequence of Streptomyces caatingaensis CMAA 1322, a New Abiotic Stress-Tolerant Actinomycete Isolated from Dried Lake Bed Sediment in the Brazilian Caatinga Biome.

The genome sequence of the first Streptomyces species isolated from the Brazilian Caatinga is reported here. Genes related to environmental stress tolerance were prevalent and included many secondary metabolic gene clusters.

Draft Genome Sequence of Bacillus sp. Strain CMAA 1185, a Cellullolytic Bacterium Isolated from Stain House Lake, Antarctic Peninsula.

The aim of this study was to report the genome sequence of the cellulolytic Bacillus sp. strain CMAA 1185, isolated from Stain House Lake, Antarctica.

Screening of Brazilian cacti rhizobacteria for plant growth promotion under drought.

Drought is one of the major problems worldwide. The search for new and efficient microorganisms, from unexplored environments, to be used in association with plants to alleviate the negative effects imposed by water stress, is an interesting alternative. Thus, cacti-associated bacteria from the Brazilian semi-arid region were isolated based on their ability to grow in medium with reduced water availability. Strains were tested for the production of exopolysaccharides (EPS), as well as in vitro plant growth promotion traits. A great proportion of the isolates belong to the genus Bacillus. From a total of forty-eight bacteria, 65% were able to grow in medium with reduced water availability (0.919Aw), exopolysaccharide production was observed for 65% of the strains. The production of indole acetic acid (IAA) exceeding 51µgmL(-1) was observed for 4% and the high solubilization of Ca-P was verified for 6% of the isolates. No strain was able to produce hydrogen cyanide (HCN), 71% produced ammonia and 79% showed a halo of carboxymethyl cellulose (CMC) degradation. Zea mays L. growth promotion under water stress (30% of field capacity) was achieved by two strains of Bacillus spp. This is the first report to describe cacti-associated bacteria from Brazilian semi-arid with plant growth-promoting abilities.

Composição química e atividade antibacteriana do óleo essencial de Hyptis leucocephala / Chemical composition and antibacterial activity of the essential oil of Hyptis leucocephala

The paper reports chemical composition and antimicrobial activity of the essential oil of Hyptis leucocephala Mart ex Benth, Lamiaceae, isolated by hydrodistillation from leaves of plants collected in Casa Nova, semi-arid region of Northeastern Brazil. A total of ten compounds were identified, of which carvacrol as the main component (average 52.82%). This essential oil was also characterized by high level of biogenetic precursor of the phenols: p-cimene (18.13%) and y-terpinene (10.72%), and by E-cariophyllene, were the most abundant sesquiterpene hydrocarbons. Bioassay revealed a significant antibacterial activity of the essential oil against Pseudomonas aeruginosa, Staphylococcus schleiferi, S. aureus, Salmonella typhi, E. coli, Bacillus pumillus, Burkholderia cepacia, Klebsiella pneumoniae with varying magnitudes. The minimal inhibition concentrations values extended from 50 to 250 µg mL-1. The essential oil showed high antioxidant activity. The free radical scavenging capacity of the oil was determined with an EC50 value of 3.41 mg mL-1. The data herein obtained show the relevant potential of H. leucocephala as a source of potent bioactivity compounds.(AU)

O artigo relata composição química e atividade antimicrobiana do óleo essencial de Hyptis leucocephala Mart ex Benth, Lamiaceae, extraído pelo método de hidrodestilação das folhas, coletadas em Casa Nova, região de Caatinga do semi-árida do Nordeste do Brasil. Foram identificados dez compostos majoritários, dos quais carvacrol como o componente principal (média 52,82%). O óleo essencial também foi caracterizado por apresentar níveis elevados de precursores biogenéticos dos fenóis: p-cimeno (18,13%) e y-terpineno (10,72%), e por E-cariophyllene, como os mais abundantes hidrocarbonetos sesquiterpeno. Os ensaios biológicos revelaram que os compostos presentes neste óleo essencial apresentaram elevada atividade antibacteriana com valores da concentração inibitória mínima entre 50 a 250 g mL-1 , principalmente contras as linhagens Pseudomonas aeruginosa, Staphylococcus schleiferi, S. aureus, Salmonella typhi, E. coli, Bacillus pumillus, Burkholderia cepacia, Klebsiella pneumoniae. Os constituintes do óleo essencial apresentaram alta eficiência na captura dos radicais livres, com elevada atividade antioxidante, com um valor de EC50 de 3,41 mg mL-1 . Os dados expostos reforçam o potencial biotecnológico do óleo essencial de H. Leucocephala, uma fonte alternativa para novos bioativos.(AU)

Composição química e atividade antibacteriana do óleo essencial de Hyptis leucocephala / Chemical composition and antibacterial activity of the essential oil of Hyptis leucocephala

The paper reports chemical composition and antimicrobial activity of the essential oil of Hyptis leucocephala Mart ex Benth, Lamiaceae, isolated by hydrodistillation from leaves of plants collected in Casa Nova, semi-arid region of Northeastern Brazil. A total of ten compounds were identified, of which carvacrol as the main component (average 52.82%). This essential oil was also characterized by high level of biogenetic precursor of the phenols: p-cimene (18.13%) and y-terpinene (10.72%), and by E-cariophyllene, were the most abundant sesquiterpene hydrocarbons. Bioassay revealed a significant antibacterial activity of the essential oil against Pseudomonas aeruginosa, Staphylococcus schleiferi, S. aureus, Salmonella typhi, E. coli, Bacillus pumillus, Burkholderia cepacia, Klebsiella pneumoniae with varying magnitudes. The minimal inhibition concentrations values extended from 50 to 250 µg mL-1. The essential oil showed high antioxidant activity. The free radical scavenging capacity of the oil was determined with an EC50 value of 3.41 mg mL-1. The data herein obtained show the relevant potential of H. leucocephala as a source of potent bioactivity compounds.

O artigo relata composição química e atividade antimicrobiana do óleo essencial de Hyptis leucocephala Mart ex Benth, Lamiaceae, extraído pelo método de hidrodestilação das folhas, coletadas em Casa Nova, região de Caatinga do semi-árida do Nordeste do Brasil. Foram identificados dez compostos majoritários, dos quais carvacrol como o componente principal (média 52,82%). O óleo essencial também foi caracterizado por apresentar níveis elevados de precursores biogenéticos dos fenóis: p-cimeno (18,13%) e y-terpineno (10,72%), e por E-cariophyllene, como os mais abundantes hidrocarbonetos sesquiterpeno. Os ensaios biológicos revelaram que os compostos presentes neste óleo essencial apresentaram elevada atividade antibacteriana com valores da concentração inibitória mínima entre 50 a 250 g mL-1 , principalmente contras as linhagens Pseudomonas aeruginosa, Staphylococcus schleiferi, S. aureus, Salmonella typhi, E. coli, Bacillus pumillus, Burkholderia cepacia, Klebsiella pneumoniae. Os constituintes do óleo essencial apresentaram alta eficiência na captura dos radicais livres, com elevada atividade antioxidante, com um valor de EC50 de 3,41 mg mL-1 . Os dados expostos reforçam o potencial biotecnológico do óleo essencial de H. Leucocephala, uma fonte alternativa para novos bioativos.