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Environmental Microbiome Mar 2023Verticillium wilt of olive (VWO), caused by Verticillium dahliae Kleb, is one of the most threatening diseases affecting olive cultivation. An integrated disease...
BACKGROUND
Verticillium wilt of olive (VWO), caused by Verticillium dahliae Kleb, is one of the most threatening diseases affecting olive cultivation. An integrated disease management strategy is recommended for the effective control of VWO. Within this framework, the use of biological control agents (BCAs) is a sustainable and environmentally friendly approach. No studies are available on the impact that the introduction of BCAs has on the resident microbiota of olive roots. Pseudomonas simiae PICF7 and Paenibacillus polymyxa PIC73 are two BCAs effective against VWO. We examined the effects of the introduction of these BCAs on the structure, composition and co-occurrence networks of the olive (cv. Picual) root-associated microbial communities. The consequences of the subsequent inoculation with V. dahliae on BCA-treated plants were also assessed.
RESULTS
Inoculation with any of the BCAs did not produce significant changes in the structure or the taxonomic composition of the 'Picual' root-associated microbiota. However, significant and distinctive alterations were observed in the topologies of the co-occurrence networks. The introduction of PIC73 provoked a diminution of positive interactions within the 'Picual' microbial community; instead, PICF7 inoculation increased the microbiota's compartmentalization. Upon pathogen inoculation, the network of PIC73-treated plants decreased the number of interactions and showed a switch of keystone species, including taxa belonging to minor abundant phyla (Chloroflexi and Planctomycetes). Conversely, the inoculation of V. dahliae in PICF7-treated plants significantly increased the complexity of the network and the number of links among their modules, suggestive of a more stable network. No changes in their keystone taxa were detected.
CONCLUSION
The absence of significant modifications on the structure and composition of the 'Picual' belowground microbiota due to the introduction of the tested BCAs underlines the low/null environmental impact of these rhizobacteria. These findings may have important practical consequences regarding future field applications of these BCAs. Furthermore, each BCA altered the interactions among the components of the olive belowground microbiota in idiosyncratic ways (i.e. PIC73 strongly modified the number of positive relations in the 'Picual' microbiota whereas PICF7 mostly affected the network stability). These modifications may provide clues on the biocontrol strategies used by these BCAs.
PubMed: 36949520
DOI: 10.1186/s40793-023-00480-2 -
Heliyon Mar 2023Barley scald is very important in temperate and wet regions worldwide and has become one of the most important foliar diseases. Before the development of recent... (Review)
Review
Barley scald is very important in temperate and wet regions worldwide and has become one of the most important foliar diseases. Before the development of recent technologies, several scientists had argued that is the causal agent of scald disease. However, the causal agent of this disease was revised and recognized as . Again recently, was suggested to be replaced as the causal agent of . The disease outbreak is depending on cool and frequent rainfall. Because of scald disease significance, numerous management practices have been advocated. Then, resistance materials, and mixing of resistant and susceptible cultivars have been used as the best management methods. Several studies have demonstrated that some cultivars and landraces of barley are resistant to scald disease during the seedling and adult growth stages. The first cultivar is "Atlas 46″ which was created from the cultivar "Turk". From biological method: , KaI245, and are very effective in treating this disease. Finally, as a last option, different fungicides have been suggested. Pathogenicity testing, seed treatments, tillage, cultivar mixtures, and biological control are all commonly overlooked in developing countries. Cultural practices such as times of fungicide application, appropriate time of sowing to scape disease, and tillage practices which are adopted for other diseases are greatly missed for scald disease. Then, we are intended to assess the various findings available on barley scald biology, taxonomy, and management.
PubMed: 36938428
DOI: 10.1016/j.heliyon.2023.e14315 -
Frontiers in Microbiology 2023Nitrogenase in some bacteria and archaea catalyzes conversion of N to ammonia. To reconstitute a nitrogenase biosynthetic pathway in a eukaryotic host is still a...
Nitrogenase in some bacteria and archaea catalyzes conversion of N to ammonia. To reconstitute a nitrogenase biosynthetic pathway in a eukaryotic host is still a challenge, since synthesis of nitrogenase requires a large number of (trogen ixation) genes. Viral 2A peptide mediated "cleavage" of polyprotein is one of strategies for multigene co-expression. Here, we show that cleavage efficiency of NifB-2A-NifH polyprotein linked by four different 2A peptides (P2A, T2A, E2A, and F2A) in ranges from ~50% to ~90%. The presence of a 2A tail in NifB, NifH, and NifD does not affect their activity. Western blotting shows that 9 Nif proteins (NifB, NifH, NifD, NifK, NifE, NifN, NifX, HesA, and NifV) from that are fused into two polyproteins 2A peptides are co-expressed in . . Expressed NifH from NifU and NifS and . NifH fusion linked 2A in . exhibits Fe protein activity.
PubMed: 36937264
DOI: 10.3389/fmicb.2023.1137355 -
Heliyon Mar 2023The rhizosphere microbes play a key role in plant nutrition and health. However, the interaction of beneficial microbes and (lobia) production remains poorly...
The rhizosphere microbes play a key role in plant nutrition and health. However, the interaction of beneficial microbes and (lobia) production remains poorly understood. Thus, we aimed to isolate and characterize the soil microbes from the rhizosphere and develop novel microbial consortia for enhancing lobia production. Fifty bacterial strains were isolated from the rhizosphere soil samples of lobia. Finally, five effective strains (e.g., sp. IESDJP-V1 and sp. IESDJP-V2, IESDJP-V3, IESDJP-V4, sp. IESDJP-V5) were identified and molecularly characterized by 16 S rDNA gene amplification. All selected strains showed positive plant growth promoting (PGP) properties in broth culture. Based on morphological, biochemical, and plant growth promoting activities, five effective isolated strains and two collected strains ( MTCC-4037 and BHUPSB17) were selected. The pot trials were conducted with seed inoculations of lobia var. Kashi Kanchan with thirty treatments and three replications. The treatment combination T3 ( sp. IESDJP-V2), T14 ( sp. IESDJP-V2 + ), T26 ( sp. IESDJP-V1+ IESDJP-V4 + ) and T27 (IESDJP-V1+ IESDJP-V5+ ) were recorded for enhancing plant growth attributes, yield, nutritional content like protein, total sugar, flavonoid and soil properties as compared to control and others. The effective treatments T3 ( sp.), T14 ( sp. IESDJP-V2 + ), T26 ( sp. IESDJP-V1+ IESDJP-V4 + ) and T27 (IESDJP-V1+ IESDJP-V5+ ) recorded as potential PGPR consortium for lobia production. The treatment of single ( sp.), duel (IESDJP-V2 + ) and triple combination (IESDJP-V1+ IESDJP-V4 + ) and (IESDJP-V1+ IESDJP-V5+ ) can be further used for developing effective indigenous consortium for lobia production under sustainable farming practices. These PGPR bio-inoculant will be cost-effective, environment-friendly and socially acceptable.
PubMed: 36895350
DOI: 10.1016/j.heliyon.2023.e13804 -
Toxins Feb 2023An antibiotic produced by 7F1 was studied. The 7F1 strain was isolated from the rhizosphere of a wheat field. Response surface methodology was used to optimize the...
An antibiotic produced by 7F1 was studied. The 7F1 strain was isolated from the rhizosphere of a wheat field. Response surface methodology was used to optimize the physicochemical parameters. The strain showed broad-spectrum activity against several plant pathogens. Identification of the strain was realized based on 16s rRNA gene and gene sequencing. The antibiotic was optimized by one-factor-at-a-time (OFAT) and response surface methodology (RSM) approaches. The suitable antibiotic production conditions were optimized using the one-factor-at-a-time method. The individual and interaction effects of three independent variables: culture temperature, initial pH, and culture time, were optimized by Box-Behnken design. The 16SrRNA gene sequence (1239 nucleotides) and gene (1111 nucleotides) were determined for strain 7F1 and shared the highest identities to those of . The results showed the optimal fermentation conditions for antibiotics produced by 7F1 were a culture temperature of 38 °C, initial pH of 8.0, and culture time of 8 h. The antibiotics produced by 7F1 include lipopeptides such as iturin A and surfactin. The results provide a theoretical basis for the development of bacteriostatic biological agents and the control of mycotoxins.
Topics: Paenibacillus polymyxa; Fusarium; Anti-Bacterial Agents; RNA, Ribosomal, 16S; Fermentation
PubMed: 36828452
DOI: 10.3390/toxins15020138 -
BMC Genomics Feb 2023Paenibacillus polymyxa WLY78 is a Gram-positive, endospore-forming and N-fixing bacterium. Our previous study has demonstrated that GlnR acts as both an activator and a...
BACKGROUND
Paenibacillus polymyxa WLY78 is a Gram-positive, endospore-forming and N-fixing bacterium. Our previous study has demonstrated that GlnR acts as both an activator and a repressor to regulate the transcription of the nif (nitrogen fixation) operon (nifBHDKENXhesAnifV) according to nitrogen availability, which is achieved by binding to the two GlnR-binding sites located in the nif promoter region. However, further study on the GlnR-mediated global regulation in this bacterium is still needed.
RESULTS
In this study, global identification of the genes directly under GlnR control is determined by using chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) and electrophoretic mobility shift assays (EMSA). Our results reveal that GlnR directly regulates the transcription of 17 genes/operons, including a nif operon, 14 nitrogen metabolism genes/operons (glnRA, amtBglnK, glnA1, glnK1, glnQHMP, nasA, nasD1, nasD2EF, gcvH, ansZ, pucR, oppABC, appABCDF and dppABC) and 2 carbon metabolism genes (ldh3 and maeA1). Except for the glnRA and nif operon, the other 15 genes/operons are newly identified targets of GlnR. Furthermore, genome-wide transcription analyses reveal that GlnR not only directly regulates the expression of these 17 genes/operons, but also indirectly controls the expression of some other genes/operons involved in nitrogen fixation and the metabolisms of nitrogen and carbon.
CONCLUSION
This study provides a GlnR-mediated regulation network of nitrogen fixation and the metabolisms of nitrogen and carbon.
Topics: Paenibacillus polymyxa; Nitrogen; Promoter Regions, Genetic; Bacterial Proteins; Binding Sites; Gene Expression Regulation, Bacterial
PubMed: 36823556
DOI: 10.1186/s12864-023-09147-1 -
Plants (Basel, Switzerland) Feb 2023Endophytes are primarily endosymbiotic bacteria and fungi that colonize the interior tissues of their host plant. They enhance the host plant's growth and attenuate...
Endophytes are primarily endosymbiotic bacteria and fungi that colonize the interior tissues of their host plant. They enhance the host plant's growth and attenuate adverse effects of biological stress. Endophytic species of many indigenous plants are an untapped resource of plant growth-promoting microorganisms that can mitigate abiotic stress effects. Thus, this study aimed to isolate endophytes from the roots and leaves of the medicinal plant to evaluate their in vitro growth-promoting capacities and drought tolerance and to characterize the most promising species. Twenty-six endophytes (fourteen bacteria and twelve fungi) were isolated and cultured from the roots and leaves of . All 26 endophytes produced flavonoids, and 14 strains produced phenolic compounds. Of the 11 strains that displayed good free radical scavenging capability (low IC) in the 1-1-diphenyl-1-picryhydrazyl radical scavenging assay, only three strains could not survive the highest drought stress treatment (40% polyethylene glycol). These 11 strains were all positive for ammonia and siderophore production and only one strain failed to produce hydrogen cyanide and solubilize phosphate. Seven isolates showed aminocyclopropane-1-carboxylate deaminase activity and differentially synthesized indole-3-acetic acid. Using molecular tools, two promising symbiotic, drought stress tolerant, and plant growth-enhancing endophytic species (EORB-2 and EOLF-5) were identified as and . The results of this study demonstrate that and should be further investigated for their drought stress mitigation and plant growth enhancement effects as they have the potential to be developed for use in sustainable agricultural practices.
PubMed: 36771720
DOI: 10.3390/plants12030638 -
Letters in Applied Microbiology Jan 2023The bacterial wilt of common bean, caused by Curtobacterium flaccumfaciens pv. flaccumfaciens(Cff) is one of the most severe diseases affecting Phaseolus vulgaris...
The bacterial wilt of common bean, caused by Curtobacterium flaccumfaciens pv. flaccumfaciens(Cff) is one of the most severe diseases affecting Phaseolus vulgaris production worldwide. This study aimed at evaluating the biocontrol potential of strains of rhizobacteria against bacterial wilt of common bean. Sequence analysis of the 16S rRNA gene was used to identify Cff isolates and also the bacterial antagonists. A soft agar overlay assay was used to select three biocontrol isolates based on their antagonistic activity against Cff. Our findings demonstrate that seed treatment using rhizobacterial P. fluorescens, Bacillus cereus, and Paenibacillus polymyxa species coupled with foliar application significantly reduced Cff disease incidence and disease severity. Therefore, biocontrol methods are potentially a safe, effective, and sustainable alternative to chemicals for controlling bacterial wilt of beans.
Topics: Phaseolus; RNA, Ribosomal, 16S; Actinomycetales; Actinobacteria; Plant Diseases
PubMed: 36688742
DOI: 10.1093/lambio/ovac011 -
Enzyme and Microbial Technology Apr 2023A novel glycoside hydrolase family 26 β-mannanase gene ppman26a was cloned from Paenibacillus polymyxa KF-1. The full-length enzyme PpMan26A and its truncated products...
A novel glycoside hydrolase family 26 β-mannanase gene ppman26a was cloned from Paenibacillus polymyxa KF-1. The full-length enzyme PpMan26A and its truncated products CBM35pp (aa 35-328) and PpMan26A-Δ205 (aa 206-656) were overexpressed in Escherichia coli. PpMan26A hydrolyzed locust bean gum, guar gum, konjac gum and ivory nut mannan, with the highest specific activity toward konjac gum. The K and k values for konjac gum were 2.13 mg/mL and 416.66 s, respectively. The oligosaccharides fraction obtained from the hydrolysis of konjac gum by PpMan26A was analyzed by matrix-assisted laser desorption ionization-time-of-flight mass spectrometer (MALDI-TOF-MS). The degradation products were mainly mannooligosaccharides with a degree of polymerization of 3-8. CBM35pp exerted strong binding activity toward mannans but without β-mannanase activity. PpMan26A-Δ205, with the deletion of the N-terminal CBM domain, showed lower substrate binding capacity, resulting in reduced enzymatic activity and thermostability. This study complements our understanding of GH26 β-mannanases and expands the potential industrial application of PpMan26A.
Topics: beta-Mannosidase; Paenibacillus polymyxa; Oligosaccharides; Mannans; Substrate Specificity; Hydrolysis
PubMed: 36680817
DOI: 10.1016/j.enzmictec.2023.110197 -
Journal of Applied Microbiology Jan 2023The increasingly widespread use of beneficial microbial inocula in agriculture gives rise to two primary needs: i) the assessment of the environmental risk, i.e. their...
AIMS
The increasingly widespread use of beneficial microbial inocula in agriculture gives rise to two primary needs: i) the assessment of the environmental risk, i.e. their impact on local soil microbiome and soil properties; ii) being able to track them and monitor their persistence and fate to both optimize their formulation and application method. In previous years, PCR-based methods have detected bacterial or fungal bioinoculant at the species or strain level. However, the selective detection, quantification, and monitoring of target microbial species in a complex ecosystem such as soil require that the tests possess high specificity and sensitivity.
METHODS AND RESULTS
The work proposes a quantitative real-time PCR detection method using TaqMan chemistry, showing high specificity and sensitivity for the Paenibacillus polymyxa K16 strain. The primer and probe sets were designed using the polymyxin gene cluster targeting pmxC and pmxE sequences. Validation tests showed that these assays allowed a discriminant and specific detection of P. polymyxa K16 in soil.
CONCLUSION
The TaqMan-assay developed could thus ensure the necessary level of discrimination required by commercial and regulatory purposes to detect and monitor the bioinoculant in soil.
Topics: Paenibacillus polymyxa; Ecosystem; Soil; Real-Time Polymerase Chain Reaction; DNA Primers; Sensitivity and Specificity; Paenibacillus
PubMed: 36626769
DOI: 10.1093/jambio/lxac048