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1.
Front Cell Infect Microbiol ; 11: 644372, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33842391

RESUMO

Culturing the entomopathogenic fungus, Beauveria bassiana, under high glucose concentrations coupled with high aeration results in a fungal developmental shift from hyphal growth to mostly blastospores (yeast-like cells). The underlying molecular mechanisms involved in this shift remain elusive. A systematic transcriptome analysis of the differential gene expression was preformed to uncover the fungal transcriptomic response to osmotic and oxidative stresses associated with the resulting high blastospore yield. Differential gene expression was compared under moderate (10% w/v) and high (20% w/v) glucose concentrations daily for three days. The RNAseq-based transcriptomic results depicted a higher proportion of downregulated genes when the fungus was grown under 20% glucose than 10%. Additional experiments explored a broader glucose range (4, 8, 12, 16, 20% w/v) with phenotype assessment and qRT-PCR transcript abundance measurements of selected genes. Antioxidant, calcium transport, conidiation, and osmosensor-related genes were highly upregulated in higher glucose titers (16-20%) compared to growth in lower glucose (4-6%) concentrations. The class 1 hydrophobin gene (Hyd1) was highly expressed throughout the culturing. Hyd1 is known to be involved in spore coat rodlet layer assembly, and indicates that blastospores or another cell type containing hydrophobin 1 is expressed in the haemocoel during the infection process. Furthermore, we found implications of the HOG signaling pathway with upregulation of homologous genes Ssk2 and Hog1 for all fermentation time points under hyperosmotic medium (20% glucose). These findings expand our knowledge of the molecular mechanisms behind blastospore development and may help facilitate large-scale industrial production of B. bassiana blastospores for pest control applications.

2.
Antonie Van Leeuwenhoek ; 114(1): 37-44, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33392934

RESUMO

A Gram-stain positive, aerobic, motile, rod-shaped bacterium designated as strain CBP-2801T was isolated as a contaminant from a culture containing maize callus in Peoria, Illinois, United States. The strain is unique relative to other Cohnella species due to its slow growth and reduced number of sole carbon sources. Phylogenetic analysis using 16S rRNA indicated that strain CBP-2801T is a Cohnella bacterium and showed the highest similarity to Cohnella xylanilytica (96.8%). Genome-based phylogeny and genomic comparisons based on average nucleotide identity confirmed the strain to be a novel species of Cohnella. Growth occurs at 15-45 °C (optimum 40 °C), pH 5-7 (optimum pH 6) and with 0-1% NaCl. The predominant fatty acids are anteiso-15:0 and 18:1 ω6c. Genome mining for secondary metabolites identified a putative biosynthetic cluster that encodes for a novel lasso peptide. In addition, this study contributes five new genome assemblies of type strains of Cohnella species, a genus with less than 30% of the type strains sequenced. The DNA G + C content is 58.7 mol %. Based on the phenotypic, phylogenetic and biochemical data strain CBP-2801T represents a novel species, for which the name Cohnella zeiphila sp. nov. is proposed. The type strain is CBP-2801T (= DSM 111598 = ATCC TSD-230).

3.
Artigo em Inglês | MEDLINE | ID: mdl-33215328

RESUMO

We isolated a filamentous, thermophilic, and first anaerobic representative of the genus Thermoactinomyces, designated strain AMNI-1T, from a biogas plant in Tyrol, Austria and report the results of a phenotypic, genetic, and phylogenetic investigation. Strain AMNI-1T was observed to form a white branching mycelium that aggregates into pellets when grown in liquid medium. Cells could primarily utilize lactose, glucose, and mannose as carbon and energy sources, with acetate accelerating and yeast extract being mandatory for growth. The optimum growth temperature and pH turned out to be 55 °C and pH 7.0, respectively, with an optimum NaCl concentration of 0-2% (w/v). 16S rRNA gene sequence comparison indicated that the genetic relatedness between strain AMNI-1T and Thermoactinomyces intermedius, Thermoactinomyces khenchelensis, and Thermoactinomyces vulgaris was less than 97%. The G + C content of the genomic DNA was 44.7 mol%. The data obtained suggest that the isolate represents a novel and first anaerobic species of the genus Thermoactinomyces, for which the name Thermoactinomyces mirandus is proposed. The type strain is AMNI-1T (= DSM 110094T = LMG 31503T). The description of the genus Thermoactinomyces is emended accordingly.

4.
Antonie Van Leeuwenhoek ; 113(12): 2213-2221, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33200278

RESUMO

A putative novel clade within the genus Streptomyces was discovered following antifungal screening against Pseudogymnoascus destructans, the causative agent of white-nose syndrome, and described using multi-locus sequencing analysis. Swabs from both the cave myotis bat (Myotis velifer) and the Brazilian free-tailed bat (Tadarida brasiliensis) in southern New Mexico bore isolates AC536, AC541T and AC563, which were characterised using phylogenetic, morphological, and phenotypic analyses. Multi-locus sequence analysis positions AC541T with neighbors Streptomyces rubidus (NRRL B-24619T), Streptomyces guanduensis (NRRL B-24617T), and Streptomyces yeochonensis (NRRL B-24245T). A complete genome of the type strain was assembled to determine its taxonomy and secondary metabolite potential. ANI comparisons between all closely related types strains are shown to be well below the 95-96% species delineation. DNA-DNA relatedness between AC541T and its nearest neighbors ranged between 23.7 and 24.1% confirming novelty. Approximately 1.49 Mb or 17.76% of the whole genome is devoted to natural product biosynthesis. The DNA G + C content of the genomic DNA of the type strain is 73.13 mol %. Micromorphology depicts ovoid spores with smooth surfaces in flexuous chains. Strains presented an ivory to yellow hue on most ISP media except inorganic salts-starch agar (ISP4) and can grow on D-glucose, mannitol, and D-fructose, but exhibited little to no growth on L-arabinose, sucrose, D-xylose, inositol, L-rhamnose, D-raffinose, and cellulose. This clade possesses the capability to grow from 10 to 45 °C and 12.5% (w/v) NaCl. There was strain growth variation in pH, but all isolates thrive at alkaline levels. Based on our polyphasic study of AC541T, the strain warrants the assignment to a novel species, for which the name Streptomyces buecherae sp. nov. is proposed. The type strain is AC541T (= JCM 34263T, = ATCC TSD201T).

5.
Antonie Van Leeuwenhoek ; 113(12): 2223-2242, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33179199

RESUMO

Bacillus cereus sensu lato strains (B. cereus group) are widely distributed in nature and have received interest for decades due to their importance in insect pest management, food production and their positive and negative repercussions in human health. Consideration of practical uses such as virulence, physiology, morphology, or ill-defined features have been applied to describe and classify species of the group. However, current comparative studies have exposed inconsistencies between evolutionary relatedness and biological significance among genomospecies of the B. cereus group. Here, the combined analyses of core-based phylogeny and all versus all Average Nucleotide Identity values based on 2116 strains were conducted to update the genomospecies circumscriptions within B. cereus group. These analyses suggested the existence of 57 genomospecies, 37 of which are novel, thus indicating that the taxonomic identities of more than 39% of the analyzed strains should be revised or updated. In addition, we found that whole-genome in silico analyses were suitable to differentiate genomospecies such as B. anthracis, B. cereus and B. thuringiensis. The prevalence of toxin and virulence factors coding genes in each of the genomospecies of the B. cereus group was also examined, using phylogeny-aware methods at wide-genome scale. Remarkably, Cry and emetic toxins, commonly assumed to be associated with B. thuringiensis and emetic B. paranthracis, respectively, did not show a positive correlation with those genomospecies. On the other hand, anthrax-like toxin and capsule-biosynthesis coding genes were positively correlated with B. anthracis genomospecies, despite not being present in all strains, and with presumably non-pathogenic genomospecies. Hence, despite these features have been so far considered relevant for industrial or medical classification of related species of the B. cereus group, they were inappropriate for their circumscription. In this study, genomospecies of the group were accurately affiliated and representative strains defined, generating a rational framework that will allow comparative analysis in epidemiological or ecological studies. Based on this classification the role of specific markers such as Type VII secretion system, cytolysin, bacillolysin, and siderophores such as petrobactin were pointed out for further analysis.

7.
Antonie Van Leeuwenhoek ; 113(12): 2041-2052, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33094436

RESUMO

The aim of this investigation was to isolate and identify Bacillus species isolated from the internal microbiota of Red sea stingrays as potential probiotics. An initial assay on the ability of the isolates to control stingray pathogens of Vibrio species led to the selection of one highly antagonistic isolate. The most potent isolate was identified based on whole genome phylogeny as Bacillus velezensis AMB-y1. Genome mining for secondary metabolites identified five antibacterial biosynthetic clusters that produce, bacilysin, bacillaene, difficidin, macrolactin and mersacidin. Genome mining also identified two antifungal biosynthetic clusters which encode genes to produce bacillomycin D and fengycin. The genome mining also identified an unknown NRPS-transAT-PKS cluster that likely produced another compound with antibiotic activity. The strain was further characterized by the assessment of abiotic stress tolerances that are required in potential probiotic agents. The selected isolate had promising results in abiotic stress tolerance; pH tolerance within the range from 4.0 to 8.0, able to survive concentrations of bile salt up to 0.4% and sodium chloride from 0 to 6.5%. In addition, the strain showed a value of hydrophobicity (31%) along with a higher value of auto-aggregation (49.9%), which demonstrates its potential ability to adhere to the intestinal wall on the basis of its cell surface traits. The strain was evaluated for susceptibility to antimicrobials and the novel B. velezensis AMB-y1 has potential to be used as a probiotic in aquaculture to control marine fish and stingray pathogens.

8.
Antonie Van Leeuwenhoek ; 113(9): 1247-1261, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32564276

RESUMO

The objective of this work was to evaluate the effectiveness of the putative biocontrol agents (PBA) Bacillus paralicheniformis and Trichoderma asperelloides in vitro and in vivo to control two of the most important tomato plant diseases: vascular wilt (Fusarium oxysporum) and early blight (Alternaria alternata). The assessment of the in vitro interactions between the PBA and the phytopathogenic fungi was performed by dual confrontation assays. The biocontrol effectiveness of the individual and combined PBA treatments towards individual phytopathogen inoculations was evaluated in tomato plants. T. asperelloides was able to exert an outstanding mycoparasitic effect on both phytopathogenic fungi in the in vitro tests by hyphal strangulation and penetration. In addition, the individual PBA treatments were effective in the biocontrol of A. alternata and F. oxysporum in tomato plants reducing the plant disease severity in more than 53.8 and 66.7% for each of the pathogens, respectively. On the other hand, the combined use of the tested strains showed similar effectiveness in the biocontrol of A. alternata, but no synergism was observed. In addition, it was concluded that B. paralicheniformis protected the plants from the attack of A. alternata through the induction of the systemic resistance of the plant. This study demonstrated the effectiveness of the individual and combined use of the strains tested for the biocontrol of A. alternata and F. oxysporum in tomato plants.

9.
Nat Microbiol ; 5(8): 987-994, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32514073

RESUMO

The assembly of single-amplified genomes (SAGs) and metagenome-assembled genomes (MAGs) has led to a surge in genome-based discoveries of members affiliated with Archaea and Bacteria, bringing with it a need to develop guidelines for nomenclature of uncultivated microorganisms. The International Code of Nomenclature of Prokaryotes (ICNP) only recognizes cultures as 'type material', thereby preventing the naming of uncultivated organisms. In this Consensus Statement, we propose two potential paths to solve this nomenclatural conundrum. One option is the adoption of previously proposed modifications to the ICNP to recognize DNA sequences as acceptable type material; the other option creates a nomenclatural code for uncultivated Archaea and Bacteria that could eventually be merged with the ICNP in the future. Regardless of the path taken, we believe that action is needed now within the scientific community to develop consistent rules for nomenclature of uncultivated taxa in order to provide clarity and stability, and to effectively communicate microbial diversity.


Assuntos
Archaea/classificação , Bactérias/classificação , Archaea/genética , Bactérias/genética , DNA Bacteriano , Metagenoma , Filogenia , Células Procarióticas/classificação , Análise de Sequência de DNA , Terminologia como Assunto
10.
Antonie Van Leeuwenhoek ; 113(7): 973-987, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32279200

RESUMO

Onions can be damaged by Fusarium basal rot caused by the soilborne fungus Fusarium oxysporum f. sp. cepae (FOC). Control of this pathogen is challenging since there is limited genetic resistance in onion. The identification of molecules that inhibit this pathogen is needed. Antagonism screening showed Brevibacillus fortis NRS-1210 secreted antifungal compounds into growth medium. The spent growth medium, diluted 1:1, inhibited growth of FOC conidia after seven hours and killed 67-91% of conidia after 11 h. The spent medium also inhibited growth of propagules from F. graminearum, F. proliferatum, F. verticillioides and Galactomyces citri-aurantii. Full strength spent growth medium did not effectively kill FOC conidia and chlamydospores inoculated into a sand cornmeal mixture. In silico analysis of the B. fortis NRS-1210 genome indicated the biosynthetic clusters of several antibiotics. Fractionation of spent medium followed by reverse-phase liquid chromatography with tandem mass spectrometry analysis found that fractions with the most antifungal activity contained a combination of edeines A, B and F and no other recognized antibiotics. 1H NMR signals of the active fraction corresponded to edeine, a pentapeptide with broad spectrum antimicrobial activity which blocks translation in both prokaryotes and eukaryotes. Comparative genomics of Brevibacillus genomes shows edeine producers form a clade which consists of: Brevibacillus brevis, Brevibacillus formosus, 'Brevibacillus antibioticus', Brevibacillus schisleri, Brevibacillus fortis, and Brevibacillus porteri. This observation suggests edeine played an important role in the evolution and speciation of the Brevibacillus genus.

11.
Antonie Van Leeuwenhoek ; 113(1): 1-12, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31721032

RESUMO

Bacillus subtilis currently encompasses four subspecies, Bacillus subtilis subsp. subtilis, Bacillus subtilis subsp. inaquosorum, Bacillus subtilis subsp. spizizenii and Bacillus subtilis subsp. stercoris. Several studies based on genomic comparisons have suggested these subspecies should be promoted to species status. Previously, one of the main reasons for leaving them as subspecies was the lack of distinguishing phenotypes. In this study, we used comparative genomics to determine the genes unique to each subspecies and used these to lead us to the unique phenotypes. The results show that one difference among the subspecies is they produce different bioactive secondary metabolites. B. subtilis subsp. spizizenii is shown conserve the genes to produce mycosubtilin, bacillaene and 3,3'-neotrehalosadiamine. B. subtilis subsp. inaquosorum is shown conserve the genes to produce bacillomycin F, fengycin and an unknown PKS/NRPS cluster. B. subtilis subsp. stercoris is shown conserve the genes to produce fengycin and an unknown PKS/NRPS cluster. While B. subtilis subsp. subtilis is shown to conserve the genes to produce 3,3'-neotrehalosadiamine. In addition, we update the chemotaxonomy and phenotyping to support their promotion to species status.


Assuntos
Bacillus subtilis/classificação , Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Genoma Bacteriano/genética , Lipopeptídeos/metabolismo , Lipoproteínas/metabolismo , Peptídeos Cíclicos/metabolismo , Polienos/metabolismo
12.
Microbiol Res ; 229: 126331, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31521945

RESUMO

The uses of halotolerant bacteria isolated from naturally saline habitats have the potential to be useful crop protection agents for plants in stressful conditions. These beneficial microbes generate several plant growth regulators and bioactive molecules, which enhance plant protection from adversities, such as plant pathogens, salts and metals stresses. In this study, 15 halotolerant bacterial strains endowed with important antimicrobial activities were isolated from Sfax solar saltern (Tunisia). All of these strains were characterized by biochemical and molecular tools aiming to investigate their in-vitro and in-vivo antifungal potentialities, plant growth promotion capabilities and metal tolerance abilities under saline stress condition. The 16S rRNA gene sequencing showed that the isolated strains were affiliated to different phylum and three species were described for the first time as plant growth promoting strains (Idiomarina zobelli FMH6v, Nesterenkonia halotolerans FMH10 and Halomonas janggokensis FMH54). The tested strains exhibited several potentialities: to tolerate high salt and heavy metal concentrations, to produce biosurfactants, exopolysaccharides and extracellular hydrolytic enzymes, to form biofilms and to liberate plant promoting substances. Eight strains were able to protect tomatoes fruits from the proliferation of the fungal disease caused by Botrytis cinerea and six strains improved plant vigor indexes. Principal component analysis showed an important correlation between in-vitro and in-vivo potentialities and two strains Bacillus velezensis FMH2 and Bacillus subtilis subsp. spizizenii FMH45 were statistically considered as the most effective strains in protecting plants from fungal pathogens attack and promoting the growth of tomatoes seedlings under saline and multi heavy-metals stress conditions.


Assuntos
Bactérias/isolamento & purificação , Fenômenos Fisiológicos Bacterianos , Lycopersicon esculentum/microbiologia , Água do Mar/microbiologia , Cloreto de Sódio/metabolismo , Bactérias/classificação , Bactérias/genética , Botrytis/fisiologia , Lycopersicon esculentum/crescimento & desenvolvimento , Doenças das Plantas/microbiologia , Salinidade , Água do Mar/química , Plântula/crescimento & desenvolvimento , Plântula/microbiologia , Cloreto de Sódio/análise , Estresse Fisiológico , Tunísia
13.
Front Microbiol ; 10: 1794, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31440222

RESUMO

Iturins and closely related lipopeptides constitute a family of antifungal compounds known as iturinic lipopeptides that are produced by species in the Bacillus subtilis group. The compounds that comprise the family are: iturin, bacillomycin D, bacillomycin F, bacillomycin L, mycosubtilin, and mojavensin. These lipopeptides are prominent in many Bacillus strains that have been commercialized as biological control agents against fungal plant pathogens and as plant growth promoters. The compounds are cyclic heptapeptides with a variable length alkyl sidechain, which confers surface activity properties resulting in an affinity for fungal membranes. Above a certain concentration, enough molecules enter the fungal cell membrane to create a pore in the cell wall, which leads to loss of cell contents and cell death. This study identified 330 iturinic lipopeptide clusters in publicly available genomes from the B. subtilis species group. The clusters were subsequently assigned into distinguishable types on the basis of their unique amino acid sequences and then verified by HPLC MS/MS analysis. The results show some lipopeptides are only produced by one species, whereas certain others can produce up to three. In addition, four species previously not known to produce iturinic lipopeptides were identified. The distribution of these compounds among the B. subtilis group species suggests that they play an important role in their speciation and evolution.

14.
J Econ Entomol ; 112(6): 2584-2596, 2019 12 09.
Artigo em Inglês | MEDLINE | ID: mdl-31329233

RESUMO

Six fungal isolates of Beauveria bassiana (Balsamo) Vuillemin and one isolate of Metarhizium anisopliae (Metschnikoff) Sorokin were isolated and evaluated for their pathogenicity to Icerya seychellarum (Westwood) and Aulacaspis tubercularis Newstead. There is a positive correlation between the concentration of the fungal blastospore concentrations and the percentage of mortality. Bio-efficacy increased significantly after inoculation with increasing concentration of blastospores and elapsed time up to 12 d after inoculation. The mortality of nymphs exposed to fungal isolates at various concentrations varied between 2.5 and 88.8%. Probit analysis of data at 95% confidence limits of LC50 and LT50s showed significant differences in the susceptibility of nymphs of I. seychellarum and A. tubercularis to the tested fungal isolates. The fungal isolates of Egy-6 and Egy-9 were the most effective against I. seychellarum and A. tubercularis, respectively. They had the lowest LC50 (4.20 × 105 and 5.71 × 103 blastospore ml-1) and LT50 (ranged from 4.61 to 9.79 and 4.84 to 8.71 d), respectively. The current study showed that all the fungal isolates yielded moderate mortality rates of nymphs and adult female populations of both the tested insect pests. To our knowledge, this is the first report of bio-efficacy of Beauveria and Metarhizium isolates against members of the Diaspidadae and Monophlebidae family insects. These results establish that the use of these native entomopathogenic fungi isolates of B. bassiana (Egy-3, Egy-4, Egy-6, Egy-7, Egy-9, and Egy-10) and M. anisopliae (Egy-5) could be considered for further development as microbial control agents of the mealybug and scale insects as a potential biological agent for use in an IPM program.


Assuntos
Beauveria , Hemípteros , Hypocreales , Mangifera , Metarhizium , Animais , Feminino , Controle Biológico de Vetores , Virulência
15.
Int J Syst Evol Microbiol ; 69(9): 2958-2962, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31310193

RESUMO

The current study evaluates the taxonomic positions of Lysinibacillusmangiferihumi, Lysinibacillus sphaericus, Lysinibacillustabacifolii and Lysinibacillus varians. Phylogenomic and genomic comparisons show the four strains are conspecific based on standard species thresholds for this genus (monophyletic and pairwise average nucleotide identities >96 %). Analysis of the 16S rRNA gene sequences provided in original descriptions with genome-derived 16S rRNA gene sequences from the current study showed significant differences in three of the four strains. Variant analysis of the 16S rRNA gene sequences using the genomic data showed that the 16S rRNA gene copies are polyallelic for these species. Previously reported distinguishing phenotypes were re-examined and the strains show phenotype congruence, with the exception of a few variable traits. Based on the rules of priority, L. mangiferihumi, L. tabacifolii and L. varians are later heterotypic synonyms of L. sphaericus.


Assuntos
Bacillaceae/classificação , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Genômica , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
16.
Antonie Van Leeuwenhoek ; 112(9): 1297-1305, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30993571

RESUMO

Four bacterial strains, with the capability of inhibiting Pseudogymnoascus destructans, the causative agent of white-nose syndrome, were isolated from male Townsend's big-eared bats (Corynorhinus townsendii, Family: Vespertilionidae) in New Mexico. Isolates AC161, AC162, AC208, and AC230T were characterised as a novel clade using morphological, phenotypic and phylogenetic analysis. A draft genome of the type strain was completed to determine its taxonomy and secondary metabolite biosynthetic potential. Multi-locus sequence analysis nests AC230T with neighbours Streptomyces scopuliridis (NRRL B-24574T), Streptomyces lushanensis (NRRL B-24994T), Streptomyces odonnellii (NRRL B-24891T) and Streptomyces niveus (NRRL 2466T). Further phylogenetic analysis showed the MLSA distances between AC230T and its near neighbours are much greater than the generally accepted threshold (> 0.007) for bacterial species delineation. DNA-DNA relatedness between AC230T and its near neighbours ranged between 25.7 ± 2.1 and 29.9 ± 2.4%. The DNA G+C content of the genomic DNA of the type strain is 71.7 mol%. Isolate AC230T presents a white to ivory hue on most ISP media and its micromorphology exhibits ovoid spores with smooth surfaces in flexuous chains. Based on our study of AC230T, the strain warrants the assignment to a novel species, for which the name Streptomyces corynorhini sp. nov. is proposed. The type strain is AC230T (= JCM 33171T, = ATCC TSD155T).


Assuntos
Quirópteros/microbiologia , Streptomyces/classificação , Streptomyces/isolamento & purificação , Animais , Técnicas de Tipagem Bacteriana , Composição de Bases , Redes e Vias Metabólicas/genética , Microscopia Eletrônica de Varredura , Tipagem de Sequências Multilocus , New Mexico , Hibridização de Ácido Nucleico , Filogenia , Esporos Bacterianos/ultraestrutura , Streptomyces/genética , Streptomyces/fisiologia , Sequenciamento Completo do Genoma
17.
Antonie Van Leeuwenhoek ; 112(8): 1161-1167, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30820713

RESUMO

A strain of a Gram-positive, strictly aerobic, motile, rod-shaped, endospore forming bacterium was originally isolated from rhizospheric soil of a pepper plant when screening and bioprospecting for plant beneficial microorganisms. Phylogenetic analysis of the 16S rRNA gene sequences indicated that this strain, PB300T, is closely related to Lysinibacillus macroides DMS 54T (99.6%) and Lysinibacillus xylanilyticus DSM 23493T (99.4%). In phenotypic characterisation, the novel strain was found to grow between 15 and 40 °C and tolerate up to 10% (w/v) NaCl. Furthermore, the strain was found to grow in media with pH 5 to 10 (optimal growth at pH 7.0). The predominant cellular fatty acids were observed to be iso-C15 : 0 (56.6 %), anteiso-C15 : 0 (14.6%), C16 :1ω7C alcohol (9.3%) and C16 : 0 (7.1%). The cell wall peptidoglycan contains lysine-aspartic acid, as in its close relatives. A draft genome was completed and the DNA G + C content was determined to be 37.5% (mol content). A phylogenomic analysis of the core genome of the new strain and 5 closely related type strains of the genus Lysinibacillus revealed that this strain formed a distinct monophyletic clade with the nearest neighbour being Lysinibacillus boronitolerans. DNA-DNA relatedness studies using in silico DNA-DNA hybridizations (DDH) showed relationships for the new strain were below the species threshold of 70%. Based upon the consensus of phylogenetic and phenotypic analyses, we conclude that this strain represents a novel species within the genus Lysinibacillus, for which the name Lysinibacillus capsici sp. nov. is proposed, with type strain PB300T (= NRRL B-65515T, = CCUG 72241T).


Assuntos
Bacillaceae/classificação , Bacillaceae/isolamento & purificação , Microbiologia do Solo , Bacillaceae/química , Bacillaceae/genética , Técnicas de Tipagem Bacteriana , Composição de Bases , Capsicum/crescimento & desenvolvimento , Parede Celular/química , Análise por Conglomerados , Citosol/química , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Ácidos Graxos/análise , Hibridização de Ácido Nucleico , Peptidoglicano/análise , Filogenia , RNA Ribossômico 16S/genética , Rizosfera , Análise de Sequência de DNA
18.
Antonie Van Leeuwenhoek ; 112(7): 991-999, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30693434

RESUMO

During a screen for antifungal activity of Brevibacillus strains in the Northern Regional Research Laboratory collection we identified two strains with strong activity. Subsequent genomic sequencing and phylogenomic analysis revealed that these strains (NRRL NRS-1210T and NRRL B-41110T) are likely novel species. To confirm their taxonomic placement, we conducted a 16S rRNA phylogenetic analysis and subsequently sequenced the genomes of 10 Brevibacillus type strains with a 16S homology > 97%. Phylogenomic analysis of these type strains and of representative Brevibacillus strains deposited in GenBank also identified several novel clades that should be recognised as novel species. For one of these novel clades, we were able to obtain a publicly available isolate (ATCC 35690T) that could serve as a type strain. The three new species were subjected to a polyphasic characterisation to confirm their taxonomic status. Cells of strains NRRL NRS-1210T, NRRL B-41110T and ATCC 35690T are Gram-staining positive, motile and form tan colonies. All three strains are obligate aerobic mesophiles with a broad pH range for growth. The two most prominent fatty acids of the three strains were identified as iso-C15:0 and anteiso-C15:0. The DNA G+C contents of strains NRRL NRS-1210T, NRRL B-41110T and ATCC 35690T are 47.2 mol%, 47.1 mol% and 47.3 mol%, respectively. Based on these characteristics, three novel species are proposed: Brevibacillus fortis sp. nov. (NRRL NRS-1210T = DSM 9886T = ATCC 51666T), Brevibacillus porteri sp. nov. (NRRL B-41110T = KACC 19693T) and Brevibacillus schisleri sp. nov. (ATCC 35690T = LMG 17055T).


Assuntos
Brevibacillus/classificação , Filogenia , Composição de Bases , Brevibacillus/genética , Brevibacillus/isolamento & purificação , Brevibacillus/metabolismo , DNA Bacteriano/genética , DNA Ribossômico/genética , Ácidos Graxos/química , Ácidos Graxos/metabolismo , Genoma Bacteriano , RNA Ribossômico 16S/genética
19.
Microbiol Res ; 216: 12-22, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30269851

RESUMO

Selecting entomopathogenic fungal isolates with resilience to environmental stresses, optimal mass production characteristics, and with high virulence to target pests favors the development of mycopesticides. A case in point, Cordyceps (= Isaria) javanica has been extensively investigated for non-chemical control of whiteflies worldwide. We phylogenetically characterized 11 native C. javanica isolates from Northeastern and Central Brazil. These isolates were screened for tolerance to heat-shock, UV-B radiation, osmotic and oxidative stresses, as well as conidial production on cereal grain and insecticidal activity against the whitefly Bemisia tabaci (MEAM 1) in the laboratory. All isolates were pathogenic to whiteflies and significant (3-fold) differences in median lethal concentration were observed among isolates. Furthermore, pronounced differences among isolates were found for stress factors and conidial production. Using principal component analysis, our results highlighted three major clusters formed by isolates (i) resistant to osmotic and oxidative stress, (ii) resilient to UV-B, and (iii) with high virulence, conidial production and heat tolerance. Overall, isolate CG1228 performed best based on multi-stress resistance, mass production and virulence attributes in the laboratory. This study highlights the importance of exploring natural variation in entomopathogenic fungi for selection of appropriate isolates for effective biocontrol of insect pests coupled with mass production characteristics and abiotic stress tolerances.


Assuntos
Cordyceps/isolamento & purificação , Cordyceps/fisiologia , Fenótipo , Reprodução Assexuada/fisiologia , Estresse Fisiológico/fisiologia , Aclimatação/fisiologia , Brasil , Cordyceps/patogenicidade , Cordyceps/efeitos da radiação , Resposta ao Choque Térmico , Temperatura Alta , Inseticidas , Análise Multivariada , Pressão Osmótica , Estresse Oxidativo , Controle Biológico de Vetores/métodos , Filogenia , Esporos Fúngicos/crescimento & desenvolvimento , Raios Ultravioleta , Virulência
20.
Microbiol Res ; 216: 40-46, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30269855

RESUMO

A strain of bacteria in the Bacillus subtilis species complex was isolated from a building's air vent in the Washington DC area, USA, and produced strong antifungal activity with in vitro assays. This strain, designated (HU Biol-II), showed pronounced inhibitory effects on mycelial growth of a wide spectrum of fungi. The objectives of this study were to use genome sequencing to confirm the taxonomy of HU Biol-II, evaluate its antifungal activity and implement genome mining and HPLC-MS/MS to characterize the bioactive secondary metabolites. The strain, as determined by multilocus sequence alignment analysis, was identified as a member of Bacillus subtilis subsp. inaquosorum clade. Core genome phylogeny showed that the isolate is most closely related to B. subtilis subsp. inaquosorum strain DE111, a commercially produced human probiotic. The investigation identified eight bioactive metabolite clusters in the genome. HPLC MS/MS was able to confirm the production of seven of the metabolites. This study is the first to report the production of two antifungal cyclic lipopeptides (bacillomycin F and fengycin) from a member of B. subtilis subsp. inaquosorum. The strain also produced the antibacterial aurantinin B, which confirms the biosynthetic cluster responsible for its production. Comparative genomics and metabolomics demonstrated the commercial probiotic strain DE111 produced the same metabolites, with the exception of aurantinin B. These findings are the first description of the secondary metabolites produced by a strain of B. subtilis subsp. inaquosorum.


Assuntos
Antifúngicos/farmacologia , Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Lipopeptídeos/metabolismo , Lipopeptídeos/farmacologia , Antibacterianos/metabolismo , Antibacterianos/farmacologia , Antibiose , Antifúngicos/isolamento & purificação , Bacillus subtilis/classificação , Bacillus subtilis/isolamento & purificação , Sequência de Bases , DNA Bacteriano , Fungos/efeitos dos fármacos , Tipagem de Sequências Multilocus , Micélio/efeitos dos fármacos , Micélio/crescimento & desenvolvimento , Peptídeos Cíclicos/metabolismo , Peptídeos Cíclicos/farmacologia , Filogenia , Polienos/metabolismo , Polienos/farmacologia , Metabolismo Secundário/genética , Alinhamento de Sequência
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