scholarly journals Potential antagonistic rhizobacteria to control Colletotrichum scovillei, the cause of anthracnose disease in chili pepper

2020 ◽  
Vol 21 (6) ◽  
Author(s):  
Dewa Ngurah Suprapta ◽  
Anak Agung Ketut Darmadi ◽  
Khamdan Khalimi

Abstract. Darmadi AAK, Suprapta DN, Khalimi K. 2020. Potential antagonistic rhizobacteria to control Colletotrichum scovillei, the cause of anthracnose disease in chili pepper. Biodiversitas 21: 2727-2734. Six species of Colletotrichum were identified as the cause of anthracnose disease on Bali Island, Indonesia in 2018. These species were C. scovillei, C. acutatum, C. nymphaeae, C. gloesporioides, C. truncatum, and C. fructicola. Among them, C. scovillei was the most prevalent at 55% of all samples tested. This study was conducted to find potential antagonistic rhizobacteria isolated from various rhizospheres of plants grown in Bali. A total of 1,040 rhizobacteria isolates were tested for their antagonistic activity against the growth of C. scovillei on potato dextrose agar. Results showed that 10 isolates inhibited the growth of C. scovillei by more than 80%. Among these isolates C1 and C7B possessed inhibitory activity at 94.9% and 94.3%, respectively. Molecular identification based on analysis of 16S rRNA gene showed that isolate C1 belonged to the species Paenibacillus polymyxa, whereas isolate C7B was identified as Bacillus siamensis. According to scanning electron serious damage on mycelia of C. scovillei was observed. Wrinkles were observed on mycelia of C. scovillei grown jointly with rhizobacterial isolate C1, whereas no wrinkle was observed on C. scovillei grown solely. Three compounds were detected in the hexane phase of cell-free filtrate P. polymyxa C1, namely, 3-hydroxy-2-butanone and 2,3-butanediol. These compounds may be responsible for antifungal activity against C. scovillei.

2022 ◽  
Vol 5 ◽  
Author(s):  
Dewa Ngurah Suprapta

Anthracnose disease on chili pepper has been known to seriously interfere with the plant growth and obviously reduce the yield. The disease is caused by Colletotrichum spp. In Bali, Indonesia, six species of Colletotrichum have been identified: Colletotrichum scovillei, C. acutatum, C. nymphaeae, C. gloeosporioides, C. truncatum, and C. fructicola. However, among them the C. scovillei was found to be the most prevalent cause of anthracnose on chili pepper in Bali. Two species of antagonist against C. scovillei, namely Paenibacillus polymyxa C1 and Bacillus siamensis C7B, have been identified. In this study the effectiveness of P. polymyxa C1 formulation was evaluated under greenhouse condition on chili pepper cultivars Cabe Besar. Application of formulation was conducted by a mini hand sprayer once to five times with a week interval. Results of the study showed that treatment with five applications significantly (p < 0.05) reduced the disease incidence, disease intensity, and the yield loss of chili pepper cultivar Cabe Besar. Alose relationship was observed between the number of applications with disease intensity, with coefficient of determination (R2) at 0.929. These results revealed that the formulation of P. polymyxa C1 effectively control the anthracnose disease on chili pepper, particularly on chili pepper cultivar Cabe Besar, and thus can be recommended for field testing to confirm its stability under field conditions.


2020 ◽  
Vol 13 (2) ◽  
pp. 54-65 ◽  
Author(s):  
M.E.A. Bendaha ◽  
H.A. Belaouni

SummaryThis study aims to develop a biocontrol agent against Fusarium oxysporum f.sp. radicis-lycopersici (FORL) in tomato. For this, a set of 23 bacterial endophytic isolates has been screened for their ability to inhibit in vitro the growth of FORL using the dual plate assay. Three isolates with the most sound antagonistic activity to FORL have been qualitatively screened for siderophore production, phosphates solubilization and indolic acetic acid (IAA) synthesis as growth promotion traits. Antagonistic values of the three candidates against FORL were respectively: 51.51 % (EB4B), 51.18 % (EB22K) and 41.40 % (EB2A). Based on 16S rRNA gene sequence analysis, the isolates EB4B and EB22K were closely related to Enterobacter ludwigii EN-119, while the strain EB2A has been assigned to Leclercia adecarboxylata NBRC 102595. The promotion of tomato growth has been assessed in vitro using the strains EB2A, EB4B and EB22K in presence of the phytopathogen FORL. The treatments with the selected isolates increased significantly the root length and dry weight. Best results were observed in isolate EB4B in terms of growth promotion in the absence of FORL, improving 326.60 % of the root length and 142.70 % of plant dry weight if compared with untreated controls. In the presence of FORL, the strain EB4B improved both root length (180.81 %) and plant dry weight (202.15 %). These results encourage further characterization of the observed beneficial effect of Enterobacter sp. EB4B for a possible use as biofertilizer and biocontrol agent against FORL.


Pathogens ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 396
Author(s):  
Ewa Sajnaga ◽  
Marcin Skowronek ◽  
Agnieszka Kalwasińska ◽  
Waldemar Kazimierczak ◽  
Karolina Ferenc ◽  
...  

This study focused on the potential relationships between midgut microbiota of the common cockchafer Melolontha melolontha larvae and their resistance to entomopathogenic nematodes (EPN) infection. We investigated the bacterial community associated with control and unsusceptible EPN-exposed insects through nanopore sequencing of the 16S rRNA gene. Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes were the most abundant bacterial phyla within the complex and variable midgut microbiota of the wild M. melolontha larvae. The core microbiota was found to include 82 genera, which accounted for 3.4% of the total number of identified genera. The EPN-resistant larvae differed significantly from the control ones in the abundance of many genera belonging to the Actinomycetales, Rhizobiales, and Clostridiales orders. Additionally, the analysis of the microbiome networks revealed different sets of keystone midgut bacterial genera between these two groups of insects, indicating differences in the mutual interactions between bacteria. Finally, we detected Xenorhabdus and Photorhabdus as gut residents and various bacterial species exhibiting antagonistic activity against these entomopathogens. This study paves the way to further research aimed at unravelling the role of the host gut microbiota on the output of EPN infection, which may contribute to enhancement of the efficiency of nematodes used in eco-friendly pest management.


2021 ◽  
Author(s):  
Shuen-Huang Tsai ◽  
Yu-Ting Chen ◽  
Yu-Liang Yang ◽  
Bo-Yi Lee ◽  
Chien-Jui Huang ◽  
...  

Paenibacillus polymyxa is a beneficial bacterium for plant health. Paenibacillus polymyxa TP3 exhibits antagonistic activity toward Botrytis cinerea and alleviates gray mold symptoms on the leaves of strawberry plants. Moreover, suppression of gray mold on the flowers and fruits of strawberry plants in field trials, including vegetative cells and endospores, was demonstrated, indicating the potential of strain TP3 as a biological control agent. To examine the anti-B. cinerea compounds produced by P. polymyxa TP3, matrix‐assisted laser‐desorption/ionization time‐of‐flight mass spectrometry was performed and fusaricidin-corresponding mass spectra were detected. Moreover, fusaricidin-related signals appeared in imaging mass spectrometry of TP3 when confronted with B. cinerea. By using liquid chromatography-mass spectrometry-based molecular networking approach, several fusaricidins were identified including a new variant of m/z 917.5455 with serine in the first position of the hexapeptide. Via advanced mass spectrometry and network analysis, fusaricidin-type compounds produced by P. polymyxa TP3 were efficiently disclosed and were presumed to play roles in the antagonism against gray mold pathogen B. cinerea.


2021 ◽  
Author(s):  
Mehrnoush Tangestani ◽  
Paul Broady ◽  
Arvind Varsani

Aim: To explore seaweed-associated bacteria as prospective producers of bioactive material with antibacterial properties. Materials & methods: 143 bacterial species were isolated from the surface of 15 New Zealand marine macroalgae. Bacterial extracts obtained using dimethyl sulfoxide and ethyl acetate were screened for antagonistic activities against three antimicrobial susceptibility indicators: Kocuria rhizophila, Staphylococcus epidermidis and Escherichia coli, using well-diffusion method. For selected species, minimum inhibitory concentration was determined, followed by a phylogenetic identification based on 16S rRNA gene sequences. Results: Among all bacteria screened, seven that belonged to the genera Vibrio, Pseudoalteromonas, Psychromonas and Cobetia, showed antagonistic activity against all three indicators. Conclusion: Seaweed-associated bacteria produce bioactive compounds with antimicrobial potential and possible biomedical application in aquatic habitats.


Agronomy ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 621 ◽  
Author(s):  
Ahmad ◽  
Naseer ◽  
Hussain ◽  
Zahid Mumtaz ◽  
Mustafa ◽  
...  

Chickpea is an important leguminous crop that improves soil fertility through atmospheric nitrogen fixation with the help of rhizobia present in nodules. Non-rhizobia endophytes are also capable of inducing nodulation and nitrogen fixation in leguminous crops. The aim of the current study was to isolate, characterize and identify the non-rhizobia endophytic bacterial strains from root nodules of chickpea. For this purpose, more than one hundred isolates were isolated from chickpea root nodules under aseptic conditions and were confirmed as endophytes through re-isolating them from root nodules of chickpea after their inoculation. Nineteen confirmed endophytic bacterial strains revealed significant production of indole acetic acid (IAA) both in presence and absence of L-tryptophan and showed their ability to grow under salt, pH and heavy metal stresses. These strains were evaluated for in vitro plant growth promoting (PGP) traits and results revealed that seven strains showed solubilization of P and colloidal chitin along with possessing catalase, oxidase, urease and chitinase activities. Seven P-solubilizing strains were further evaluated in a jar trial to explore their potential for promoting plant growth and induction of nodulation in chickpea roots. Two endophytic strains identified as Paenibacillus polymyxa ANM59 and Paenibacillus sp. ANM76 through partial sequencing of the 16S rRNA gene showed the maximum potential during in vitro PGP activities and improved plant growth and nodulation in chickpea under the jar trial. Use of these endophytic strains as a potential biofertilizer can help to reduce the dependence on chemical fertilizers while improving crop growth and soil health simultaneously.


2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Feina Li ◽  
Shaowei Liu ◽  
Qinpei Lu ◽  
Hongyun Zheng ◽  
Ilya A. Osterman ◽  
...  

Mangrove is a rich and underexploited ecosystem with great microbial diversity for discovery of novel and chemically diverse antimicrobial compounds. The goal of the study was to explore the pharmaceutical actinobacterial resources from mangrove soil and gain insight into the diversity and novelty of cultivable actinobacteria. Consequently, 10 mangrove soil samples were collected from Futian and Maoweihai of China, and the culture-dependent method was employed to obtain actinobacteria. A total of 539 cultivable actinobacteria were isolated and distributed in 39 genera affiliated to 18 families of 8 orders by comparison analysis of partial 16S rRNA gene sequences. The dominant genus was Streptomyces (16.0 %), followed by Microbacterium (14.5 %), Agromyces (14.3 %), and Rhodococcus (11.9 %). Other 35 rare actinobacterial genera accounted for minor proportions. Notably, 11 strains showed relatively low 16S rRNA gene sequence similarities (< 98.65 %) with validly described species. Based on genotypic analyses and phenotypic characteristics, 115 out of the 539 actinobacterial strains were chosen as representative strains to test their antibacterial activities against “ESKAPE” bacteria by agar well diffusion method and antibacterial mechanism by the double fluorescent protein reporter system. Fifty-four strains in 23 genera, including 2 potential new species, displayed antagonistic activity in antibacterial assay. Meanwhile, 5 strains in 3 genera exhibited inhibitory activity on protein biosynthesis due to ribosome stalling. These results demonstrate that cultivable actinobacteria from mangrove soil are potentially rich sources for discovery of new antibacterial metabolites and new actinobacterial taxa.


2017 ◽  
Vol 1 (3) ◽  
pp. 158-168 ◽  
Author(s):  
Kristi Gdanetz ◽  
Frances Trail

Manipulating plant-associated microbes to reduce disease or improve crop yields requires a thorough understanding of interactions within the phytobiome. Plants were sampled from a wheat/maize/soybean crop rotation site that implements four different crop management strategies. We analyzed the fungal and bacterial communities of leaves, stems, and roots of wheat throughout the growing season using 16S and fungal internal transcribed spacer 2 rRNA gene amplicon sequencing. The most prevalent operational taxonomic units (OTUs) were shared across all samples, although levels of the low-abundance OTUs varied. Endophytes were isolated from plants, and tested for antagonistic activity toward the wheat pathogen Fusarium graminearum. Antagonistic strains were assessed for plant protective activity in seedling assays. Our results suggest that microbial communities were strongly affected by plant organ and plant age, and may be influenced by management strategy.


2019 ◽  
Vol 8 (1) ◽  
pp. 65 ◽  
Author(s):  
Lorena Barra-Bucarei ◽  
Andrés France Iglesias ◽  
Macarena Gerding González ◽  
Gonzalo Silva Aguayo ◽  
Jorge Carrasco-Fernández ◽  
...  

Botrytis cinerea causes substantial losses in tomato and chili pepper crops worldwide. Endophytes have shown the potential for the biological control of diseases. The colonization ability of native endophyte strains of Beauveria bassiana and their antifungal effect against B. cinerea were evaluated in Solanaceae crops. Root drenching with B. bassiana was applied, and endophytic colonization capacity in roots, stems, and leaves was determined. The antagonistic activity was evaluated using in vitro dual culture and also plants by drenching the endophyte on the root and by pathogen inoculation in the leaves. Ten native strains were endophytes of tomato, and eight were endophytes of chili pepper. All strains showed significant in vitro antagonism against B. cinerea (30–36%). A high antifungal effect was observed, and strains RGM547 and RGM644 showed the lowest percentage of the surface affected by the pathogen. Native strains of B. bassiana colonized tomato and chili pepper tissues and provided important levels of antagonism against B. cinerea.


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