Biocontrol Of Pathogenic Fungi Research Articles

Effect of antagonistic bacteria and its formulation to control fusarium wilt disease on shallot

Biocontrol of pathogenic fungi using antagonistic bacteria isolated from the soil (rhizosphere) is expected to suppress plant diseases to obtain good quality of yield, and thus support sustainable agriculture. The study aimed to formulate and scale up the production of rhizosphere-based bacterial biopesticides that effective in suppressing the onset of Fusarium wilt disease caused by Fusarium oxysporum f.sp. cepae on shallot. The experiment to evaluate the effectiveness of biocontrol agents against Fusarium wilt disease was carried out employing shallot cv. ‘bima curut’ in the field (Patrol-Indramayu,West Java), from May to August 2018 growing season. The experimental plot of 1.20 m x 18 m, was prepared using plant spacing of 15 × 10 cm. The solid formulation of kaolin-based bacteria (containing bacterial cells of 109 CFU/mL) was applied with variation of four concentrations range from 0.3125 to 2.5 mL/L. The experiment was arranged in randomized block design with four replications. Shallot beginning at 30 days old-plant was sprayed three times at one-week intervals. The results showed that the disease intensity was significantly lower than in control. Under natural infection, the spraying application of a bacterial isolate (DSB2) using kaolin formulation (107 CFU/mL) with a formula concentration of 1.25 mL/L could reduce the disease intensity. Tuber yield of formula treatments was significantly higher than that of control. Thus, the use of bacterial formula as environmental-friendly biocontrol agent in this study might be further recommended in controlling Fusarium wilt disease on shallots.

Current Perspectives on Chitinolytic Enzymes and Their Agro-Industrial Applications.

Simple SummaryChitin is a polysaccharide that forms the outer layer of many organisms, and it is widely used in industry. Chitinases are enzymes that can break down chitin into monomeric molecules and are used in the agro-industrial sectors. Because chitin is the key structural component of marine (mollusks, crustaceans, and marine invertebrates) and other species (algae, fungi, and insects), chitinases can be employed in the marine waste management and biocontrol of pathogenic fungi and harmful insects. Chitinase also has uses in the food industry, cosmetics, medicine, waste management, crop protection, and the production of single-cell proteins, among others. This study includes detailed information on the characterization, sources, and uses of chitinases in several areas.Chitinases are a large and diversified category of enzymes that break down chitin, the world’s second most prevalent polymer after cellulose. GH18 is the most studied family of chitinases, even though chitinolytic enzymes come from a variety of glycosyl hydrolase (GH) families. Most of the distinct GH families, as well as the unique structural and catalytic features of various chitinolytic enzymes, have been thoroughly explored to demonstrate their use in the development of tailor-made chitinases by protein engineering. Although chitin-degrading enzymes may be found in plants and other organisms, such as arthropods, mollusks, protozoans, and nematodes, microbial chitinases are a promising and sustainable option for industrial production. Despite this, the inducible nature, low titer, high production expenses, and susceptibility to severe environments are barriers to upscaling microbial chitinase production. The goal of this study is to address all of the elements that influence microbial fermentation for chitinase production, as well as the purifying procedures for attaining high-quality yield and purity.

Production and immobilization of \u03b2-glucanase from Aspergillus niger with its applications in bioethanol production and biocontrol of phytopathogenic fungi

β-Glucanase has received great attention in recent years regarding their potential biotechnological applications and antifungal activities. Herein, the specific objectives of the present study were to purify, characterize and immobilize β-glucanase from Aspergillus niger using covalent binding and cross linking techniques. The evaluation of β-glucanase in hydrolysis of different lignocellulosic wastes with subsequent bioethanol production and its capability in biocontrol of pathogenic fungi was investigated. Upon nutritional bioprocessing, β-glucanase production from A. niger EG-RE (MW390925.1) preferred ammonium nitrate and CMC as the best nitrogen and carbon sources, respectively. The soluble enzyme was purified by (NH4)2SO4, DEAE-Cellulose and Sephadex G200 with 10.33-fold and specific activity of 379.1 U/mg protein. Tyrosyl, sulfhydryl, tryptophanyl and arginyl were essential residues for enzyme catalysis. The purified β-glucanase was immobilized on carrageenan and chitosan with appreciable yield. However, the cross-linked enzyme exhibited superior activity along with remarkable improved thermostability and operational stability. Remarkably, the application of the above biocatalyst proved to be a promising candidate in liberating the associate lignocellulosic reducing sugars, which was utilized for ethanol production by Saccharomyces cerevisiae. The purified β-glucanase revealed an inhibitory effect on the growth of two tested phytopathogens Fusarium oxysporum and Penicillium digitatum.

Isolation of Burkholderia sp. HQB-1, A Promising Biocontrol Bacteria to Protect Banana Against Fusarium Wilt Through Phenazine-1-Carboxylic Acid Secretion.

Fusarium wilt is a devastating soil-borne fungal disease caused by Fusarium oxysporum f.sp. cubense (Foc). In recent years, some antifungal bacteria have been applied for the prevention and biocontrol of pathogenic fungi. In our study, a bacterial strain HQB-1, isolated from banana rhizosphere soil, was cultured for investigation. It showed broad-spectrum antifungal activities against representative phytopathogenic fungi including Fusarium oxysporum, Colletotrichum gloeosporioides, Botrytis cinerea, and Curvularia fallax. The strain HQB-1 was identified as Burkholderia sp. by morphological, physiological, and biochemical examinations, confirmed by 16S rRNA gene sequence analysis. Among the metabolites produced by the strain, we identified an antifungal compound which was identified phenazine-1-carboxylic acid (PCA) (C13H8N2O2) through ultraviolet, liquid chromatography quadrupole-time of flight mass spectrometer, and nuclear magnetic response. Furthermore, PCA exhibited the lowest minimum inhibitory concentration (MIC) against F. oxysporum (1.56 μg/ml) and yielded the highest MIC against C. gloeosporioides. Pot experiments showed that application of 5 μg/ml or more of PCA efficiently controlled banana wilt and promoted the growth of banana plants. These results suggested that Burkholderia sp. HQB-1, as an important microbial resource of PCA, could be a promising biological agent against wilt diseases and promoting banana growth.

Isolation of Chitinase B [ChiB] gene from Serratia plymutica strain UBCF_13

The utilization of synthetic fungicides harms the environment. Several studies have been carried out to control disease in plants using biocontrol agents and bio fungicides that more environmentally friendly. Laboratory tests showed that bacterial isolates UBCF_13 can act as biocontrol of pathogenic fungi that have been identified as Serratia plymutica bacteria. This bacteria is capable of producing chitinase enzymes that can degrade pathogenic fungal cell walls. The study was aimed to isolate the chitinase B gene from Serratia plymuticha strain UBCF_13. Cloning of the chitinase B [ChiB] gene from the bacterial genome UBCF_13 was carried out using a PCR-based cloning strategy using specific primers. The UBCF_13 ChiB gene was successfully isolated and identified with a sequence of 1583 bp covering ORF of 1500 bp which encodes 499 amino acids. Domain analysis exhibited 2 functional domains, namely catalytic and the chitin-binding domain. The 3D analysis of the ChiB protein structure indicates a similar function with the c1ur88 template which is identified as ChiB. Further research is necessary to determine the optimal method to express and determine its detailed function.

WITHDRAWN: Structural and functional characterization for interaction of silver nanoparticles with ergostrol in Trichoderma harzianum

This article has been withdrawn: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been withdrawn at the request of the editor and publisher. The publisher regrets that an error occurred which led to the premature publication of this paper. This error bears no reflection on the article or its authors. The publisher apologizes to the authors and the readers for this unfortunate error.

Monitoring Population Size, Activity, and Distribution of gfp-luxAB-Tagged Pseudomonas fluorescens SBW25 during Colonization of Wheat.

Increasingly, focus has been directed towards the use of microorganisms as biological control agents to combat fungal disease, as an alternative to chemical fungicides. Pseudomonas fluorescens SBW25 is one bacterial strain that has been demonstrated to promote plant growth by biocontrol of pathogenic fungi. To understand the mode of action of this bacterium, information regarding its localization and metabolic activity on plants is important. In this study, a gfp/luxAB-tagged derivative of P. fluorescens SBW25, expressing the green fluorescent protein (GFP) and bacterial luciferase, was monitored during colonization of wheat starting from seed inoculation. Since bacterial luciferase is dependent on cellular energy reserves for phenotypic expression, metabolically active cells were detected using this marker. In contrast, the stable GFP fluorescence phenotype was used to detect the cells independently of their metabolic status. The combination of these two markers enabled P. fluorescens SBW25 cells to be monitored on wheat plants to determine their specific location and metabolic activity. Studies on homogenized wheat plant parts demonstrated that the seed was the preferred location of P. fluorescens SBW25 during the 65-day time period studied, but the leaves and roots were also colonized. Interestingly, the bacteria were also found to be metabolically active on all plant parts examined. In situ localization of P. fluorescens SBW25 using a combination of different microscopic techniques confirmed the preference for the cells to colonize specific regions of the seed. We speculate that the colonization pattern of P. fluorescens SBW25 can be linked to the mechanism of protection of plants from fungal infection.