scholarly journals Diversity of culturable bacteria endowed with antifungal metabolites biosynthetic characteristics associated with tea rhizosphere soil of Assam, India

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Jintu Dutta ◽  
Debajit Thakur
Keyword(s):  
Fungal Pathogens ◽  
Rhizosphere Soil ◽  
Restriction Analysis ◽  
Amino Acid Level ◽  
Antagonistic Activity ◽  
Culturable Bacteria ◽  
Bacterial Isolates ◽  
Antifungal Metabolites ◽  
Pcr Fingerprinting ◽  
Chitinase Genes

Abstract Background Rhizosphere soil is a crucial niche for the diverse beneficial microbial communities in plant-microbe interactions. This study explores the antagonistic potential and diversity of the rhizosphere soil bacteria from commercial tea estates of Assam, India which comes under the Indo-Burma mega-biodiversity hotspot. Rhizosphere soil samples were collected from six different tea estates to isolate the bacteria. The bacterial isolates were subjected to evaluate for the antagonistic activity against fungal pathogens. The potential isolates were investigated for chitinase production and the presence of chitinase gene. The bacterial genetic diversity was studied by Amplified Ribosomal DNA Restriction Analysis (ARDRA) and BOX-PCR fingerprinting. Results A total of 217 rhizobacteria were isolated from tea rhizosphere soil, out of which 50 isolates exhibited the potential antagonistic activity against fungal pathogens. Among them, 12 isolates showed extracellular chitinase activity and the presence of chitinase genes. The chitinase genes were sequenced and the analysis of the sequences was performed by using PDB protein databank at the amino acid level. It showed the presence of ChiA and ChiA74 gene in the 6 most potent isolates which are involved in the hydrolysis of chitin. These isolates also exhibited antagonistic activity against all tested fungal pathogens. The diversity of 50 antagonistic bacterial isolates were analyzed through ARDRA and BOX-PCR fingerprinting. Diversity analysis and molecular identification of the rhizosphere isolates revealed that these antagonistic isolates predominantly belonged to the genus Bacillus followed by Enterobacter, Serratia, Lysinibacillus, Pseudomonas, and Burkholderia. Conclusion The present study establishes that rhizobacteria isolated from the poorly explored tea rhizosphere soil could be a rich reservoir for the investigation of potential antagonistic bacterial candidates for sustainable agricultural and industrial applications.

scholarly journals Diversity of culturable bacteria endowed with antifungal metabolites biosynthetic characteristics associated with Tea rhizosphere soil of Assam, India  

2020 ◽  
Author(s):  
Jintu Dutta ◽  
Debajit Thakur
Keyword(s):  
Fungal Pathogens ◽  
Rhizosphere Soil ◽  
Amino Acid Level ◽  
Antagonistic Activity ◽  
Chitinase Gene ◽  
Culturable Bacteria ◽  
Bacterial Isolates ◽  
Antifungal Metabolites ◽  
Pcr Fingerprinting ◽  
Chitinase Genes

Abstract Background Rhizosphere soil is a crucial niche for the diverse beneficial microbial communities for plant-microbe interactions. This study explores the antagonistic potential and diversity of the rhizosphere soil bacteria from commercial tea estates of Assam, India which comes under Indo-Burma mega-biodiversity hotspot. Rhizosphere soil samples were collected from six different tea estates to isolate the bacteria. The bacterial isolates were subjected to evaluate for the antagonistic activity against fungal pathogens. The potential isolates were investigated for chitinase production and presence of chitinase gene. The bacterial genetic diversity was studied by ARDRA and BOX-PCR fingerprinting. Results A total of 217 rhizobacteria were isolated from tea rhizosphere soil and of which 50 isolates exhibited the potential antagonistic activity against fungal pathogens. Among them, 12 isolates showed extracellular chitinase activity and the presence of chitinase genes. The sequencing and analysis of the chitinase gene using PDB protein databank at the amino acid level showed the presence of ChiA and ChiA74 gene in the isolates which involved in the hydrolysis of chitin. The analysis showed that 6 most potential isolates exhibited antagonistic activity against all tested fungal pathogens and presence of chitinase genes within their genome. The diversity of 50 antagonistic bacterial isolates were analysed through ARDRA and BOX-PCR fingerprinting. Diversity analysis and molecular identification of the rhizosphere isolates revealed that these antagonistic isolates predominantly belonged to the genus Bacillus followed by Enterobacter, Serratia, Lysinibacillus, Pseudomonas, and Burkholderia. Conclusion The present study establishes that rhizobacteria isolated from the poorly explored tea rhizosphere soil could be a rich reservoir for the investigation of potential antagonistic bacterial candidates for sustainable agricultural and industrial applications.

Potato-associated bacteria and their antagonistic potential towards plant-pathogenic fungi and the plant-parasitic nematodeMeloidogyne incognita(Kofoid & White) Chitwood

2002 ◽  
Vol 48 (9) ◽  
pp. 772-786 ◽  
Author(s):  
Annette Krechel ◽  
Annekathrin Faupel ◽  
Johannes Hallmann ◽  
Andreas Ulrich ◽  
Gabriele Berg
Keyword(s):  
Fungal Pathogens ◽  
Bacterial Species ◽  
Pathogenic Fungi ◽  
Antagonistic Activity ◽  
Polymorphism Analysis ◽  
Culturable Bacteria ◽  
Streptomyces Species ◽  
Associated Bacteria ◽  
Antagonistic Potential

To study the effect of microenvironments on potato-associated bacteria, the abundance and diversity of bacteria isolated from the rhizosphere, phyllosphere, endorhiza, and endosphere of field grown potato was analyzed. Culturable bacteria were obtained after plating on R2A medium. The endophytic populations averaged 103and 105CFU/g (fresh wt.) for the endosphere and endorhiza, respectively, which were lower than those for the ectophytic microenvironments, with 105and 107CFU/g (fresh wt.) for the phyllosphere and rhizosphere, respectively. The composition and richness of bacterial species was microenvironment-dependent. The occurrence and diversity of potato-associated bacteria was additionally monitored by a cultivation-independent approach using terminal restriction fragment length polymorphism analysis of 16S rDNA. The patterns obtained revealed a high heterogeneity of community composition and suggested the existence of microenvironment-specific communities. In an approach to measure the antagonistic potential of potato-associated bacteria, a total of 440 bacteria was screened by dual testing for in vitro antagonism towards the soilborne pathogens Verticillium dahliae and Rhizoctonia solani. The proportion of isolates with antagonistic activity was highest for the rhizosphere (10%), followed by the endorhiza (9%), phyllosphere (6%), and endosphere (5%). All 33 fungal antagonists were characterized by testing their in vitro antagonistic mechanisms, including their glucanolytic, chitinolytic, pectinolytic, cellulolytic, and proteolytic activity, and by their BOX-PCR fingerprints. In addition, they were screened for their biocontrol activity against Meloidogyne incognita. Overall, nine isolates belonging to Pseudomonas and Streptomyces species were found to control both fungal pathogens and M. incognita and were therefore considered as promising biological control agents. Key words: biocontrol, antagonistic potential, plant-associated bacteria.

scholarly journals Survey and Identification of Date Palm Pathogens and Indigenous Biocontrol Agents

Plant Disease ◽  
2020 ◽  
Vol 104 (9) ◽  
pp. 2498-2508
Author(s):  
Resna Nishad ◽  
Talaat A. Ahmed
Keyword(s):  
Endophytic Fungi ◽  
Fungal Pathogens ◽  
Date Palm ◽  
Defense Mechanism ◽  
Pathogenic Fungi ◽  
Antagonistic Activity ◽  
Immune Defense ◽  
Biocontrol Agents ◽  
Antifungal Metabolites ◽  
Different Seasons

Fungal diseases are considered a major threat to plant growth and productivity. However, some beneficial fungi growing in the same environment protect plants from various pathogens, either by secreting antifungal metabolites or by stimulating the host immune defense mechanism. Date palms are susceptible to several fungal pathogens. Nevertheless, information on the pathogenic fungal distribution in date palm fields across different seasons is limited, especially that from Qatar. Therefore, the current study’s aim was to evaluate the pathogenic and beneficial fungal diversity and distribution, including the endophytic fungi from the date palm tissues and root-associated soil fungi, during different seasons, for the identification of indigenous biocontrol agents. Our results showed that the highest number of fungal species was isolated in fall and spring, and pathogenic fungi were isolated mainly in spring. This is the first report that in Qatar, Neodeightonia phoenicum and Thielaviopsis punctulata cause date palm root rot disease, Fusarium brachygibbosum and Fusarium equiseti cause date palm wilting, and N. phoenicum causes diplodia disease in date palm offshoots. The combinations of the fungi that did not frequently occur together in date palm rhizosphere soil were investigated to identify indigenous biocontrol agents. Based on the results, we determined that Trichoderma harzianum and Trichoderma longibrachiatum are effective antagonistic fungi against T. punctulata, N. phoenicum, F. brachygibbosum, and Fusarium solani, qualifying them as potential biocontrol agents. Antagonistic activity of endophytic fungi against the pathogens was tested; except for Ulocladium chartarum, no endophytic fungi showed antagonistic activity against the tested pathogens. [Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .

scholarly journals Assessment of Phaseolus vulgaris L and Vigna unguiculata (L.) Walp leaves for antifungal metabolites against two bean fungal pathogens Colletotricum lindemuthianum and Phaeoisariopsis griseola

2014 ◽  
Vol 13 (15) ◽  
pp. 1657-1665
Author(s):  
Alex Diana ◽  
Norentilde;a-Ramirez ra ◽  
Julian Velasquez-Ballesteros Oscar ◽  
Murillo-Perea Elizabeth ◽  
Jairo Mendez-Arteaga Jonh ◽  
...  
Keyword(s):  
Phaseolus Vulgaris ◽  
Vigna Unguiculata ◽  
Fungal Pathogens ◽  
Phaseolus Vulgaris L ◽  
Phaeoisariopsis Griseola ◽  
Antifungal Metabolites

scholarly journals Searching for Antagonistic Activity of Bacterial Isolates Derived from Food Processing Environments on Some Food-Borne Pathogenic Bacteria

2020 ◽  
Vol 49 (4) ◽  
pp. 415-423
Author(s):  
B. Baráti-Deák ◽  
Cs. Mohácsi-Farkas ◽  
Á. Belák
Keyword(s):  
Escherichia Coli ◽  
Food Processing ◽  
Pathogenic Bacteria ◽  
Inhibitory Effect ◽  
Antagonistic Activity ◽  
Bacterial Isolates ◽  
Bacterial Strains ◽  
Food Borne ◽  
Time Period ◽  
Growth Decline

Bacterial strains with inhibitory effect on Salmonella Hartford, Listeria monocytogenes, Yersinia enterocolitica, and Escherichia coli, respectively, were isolated. Out of the 64 bacteria originated from food processing environments, 20 could inhibit at least one of the tested pathogens, and it was proved that growth decline of the pathogenic bacteria was more remarkable by co-culturing than by using cell-free supernatants of the isolates. Seven different genera (Pseudomonas, Bacillus, Paenibacillus, Macrococcus, Staphylococcus, Serratia, and Rothia) reduced the pathogens’ growth during the time period of analysis, and the strongest inhibitory effect was observed after 24 h between 15 and 30 °C. Sensitivity of the tested human pathogenic bacteria against the inhibitory strains was distinct, as Y. enterocolitica could be inhibited by numerous isolates, while S. Hartford proved to be the most resistant. Our results reveal that the isolated bacteria or their excreted metabolites could hinder pathogen growth when used in sufficient quantities.

scholarly journals Phyllosphere Colonization by a Soil Streptomyces sp. Promotes Plant Defense Responses Against Fungal Infection

2020 ◽  
Vol 33 (2) ◽  
pp. 223-234 ◽  
Author(s):  
Sophie Vergnes ◽  
Damien Gayrard ◽  
Marine Veyssière ◽  
Justine Toulotte ◽  
Yves Martinez ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Fungal Pathogens ◽  
Plant Root ◽  
Defense Responses ◽  
Plant Diseases ◽  
Alternaria Brassicicola ◽  
Size Exclusion ◽  
Plant Defense Responses ◽  
Antifungal Metabolites ◽  
Root Microbiota

Streptomycetes are soil-dwelling, filamentous actinobacteria and represent a prominent bacterial clade inside the plant root microbiota. The ability of streptomycetes to produce a broad spectrum of antifungal metabolites suggests that these bacteria could be used to manage plant diseases. Here, we describe the identification of a soil Streptomyces strain named AgN23 which strongly activates a large array of defense responses when applied on Arabidopsis thaliana leaves. AgN23 increased the biosynthesis of salicylic acid, leading to the development of salicylic acid induction deficient 2 (SID2)-dependent necrotic lesions. Size exclusion fractionation of plant elicitors secreted by AgN23 showed that these signals are tethered into high molecular weight complexes. AgN23 mycelium was able to colonize the leaf surface, leading to plant resistance against Alternaria brassicicola infection in wild-type Arabidopsis plants. AgN23-induced resistance was found partially compromised in salicylate, jasmonate, and ethylene mutants. Our data show that Streptomyces soil bacteria can develop at the surface of plant leaves to induce defense responses and protection against foliar fungal pathogens, extending their potential use to manage plant diseases.

scholarly journals Identification of the Fungal Pathogens of Postharvest Disease on Peach Fruits and the Control Mechanisms of Bacillus subtilis JK-14

Toxins ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 322 ◽  
Author(s):  
Shuwu Zhang ◽  
Qi Zheng ◽  
Bingliang Xu ◽  
Jia Liu
Keyword(s):  
Biological Control ◽  
Bacillus Subtilis ◽  
Fungal Pathogens ◽  
Biological Control Agent ◽  
Storage Period ◽  
Control Agent ◽  
Antagonistic Activity ◽  
Postharvest Disease ◽  
Economic Losses ◽  
Control Mechanisms

Postharvest fungal disease is one of the significant factors that limits the storage period and marketing life of peaches, and even result in serious economic losses worldwide. Biological control using microbial antagonists has been explored as an alternative approach for the management of postharvest disease of fruits. However, there is little information available regarding to the identification the fungal pathogen species that cause the postharvest peach diseases and the potential and mechanisms of using the Bacillus subtilis JK-14 to control postharvest peach diseases. In the present study, a total of six fungal isolates were isolated from peach fruits, and the isolates of Alternaria tenuis and Botrytis cinerea exhibited the highest pathogenicity and virulence on the host of mature peaches. In the culture plates, the strain of B. subtilis JK-14 showed the significant antagonistic activity against the growth of A. tenuis and B. cinerea with the inhibitory rates of 81.32% and 83.45% at 5 days after incubation, respectively. Peach fruits treated with different formulations of B. subtilis JK-14 significantly reduced the mean disease incidences and lesion diameters of A. tenuis and B. cinerea. The greatest mean percent reduction of the disease incidences (81.99% and 71.34%) and lesion diameters (82.80% and 73.57%) of A. tenuis and B. cinerea were obtained at the concentration of 1 × 107 CFU mL−1 (colony forming unit, CFU). Treatment with the strain of B. subtilis JK-14 effectively enhanced the activity of the antioxidant enzymes-superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in A. tenuis and B. cinerea inoculated peach fruits. As such, the average activities of SOD, POD and CAT were increased by 36.56%, 17.63% and 20.35%, respectively, compared to the sterile water treatment. Our results indicate that the isolates of A. tenuis and B. cinerea are the main pathogens that cause the postharvest peach diseases, and the strain of B. subtilis JK-14 can be considered as an environmentally-safe biological control agent for the management of postharvest fruits diseases. We propose the possible mechanisms of the strain of B. subtilis JK-14 in controlling of postharvest peach diseases.

The Application of PCR Fingerprinting to the Epidemiologic Analysis of Bacterial and Fungal Pathogens

1994 ◽  
pp. 219-225
Author(s):  
G. Schönian ◽  
Y. Gräser ◽  
O. Meusel ◽  
W. Meyer ◽  
P. Buchholz ◽  
...  
Keyword(s):  
Fungal Pathogens ◽  
Pcr Fingerprinting ◽  
Epidemiologic Analysis

scholarly journals Disruption of Firmicutes and Actinobacteria abundance in tomato rhizosphere causes the incidence of bacterial wilt disease

2020 ◽  
Vol 15 (1) ◽  
pp. 330-347 ◽  
Author(s):  
Sang-Moo Lee ◽  
Hyun Gi Kong ◽  
Geun Cheol Song ◽  
Choong-Min Ryu
Keyword(s):  
Bacterial Wilt ◽  
Rhizosphere Soil ◽  
Plant Protection ◽  
Plant Immunity ◽  
Disease Suppression ◽  
Culturable Bacteria ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Individual Strain ◽  
Bacillus Niacini

AbstractEnrichment of protective microbiota in the rhizosphere facilitates disease suppression. However, how the disruption of protective rhizobacteria affects disease suppression is largely unknown. Here, we analyzed the rhizosphere microbial community of a healthy and diseased tomato plant grown <30-cm apart in a greenhouse at three different locations in South Korea. The abundance of Gram-positive Actinobacteria and Firmicutes phyla was lower in diseased rhizosphere soil (DRS) than in healthy rhizosphere soil (HRS) without changes in the causative Ralstonia solanacearum population. Artificial disruption of Gram-positive bacteria in HRS using 500-μg/mL vancomycin increased bacterial wilt occurrence in tomato. To identify HRS-specific and plant-protective Gram-positive bacteria species, Brevibacterium frigoritolerans HRS1, Bacillus niacini HRS2, Solibacillus silvestris HRS3, and Bacillus luciferensis HRS4 were selected from among 326 heat-stable culturable bacteria isolates. These four strains did not directly antagonize R. solanacearum but activated plant immunity. A synthetic community comprising these four strains displayed greater immune activation against R. solanacearum and extended plant protection by 4 more days in comparison with each individual strain. Overall, our results demonstrate for the first time that dysbiosis of the protective Gram-positive bacterial community in DRS promotes the incidence of disease.

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