The Potential of Fungi as Bio-Control Agents in Managing Colletotrichum Kahawae In Kenya

Colletotrichum kahawae is a causative fungal agent of Coffee Berry Disease (CBD) that negatively affects coffee production. Its control relies on use of resistant varieties and chemical control. Fungicides used in control of CBD are costly and pose a risk to environment and health. The study was aimed at assessing the possible antagonistic potential of fungal isolates against Colletotrichum kahawae in in vitro conditions. Five isolates were used; one isolate was collected from berries while the rest were collected from soil. Testing for antagonism against Colletorichum kahawae was done by co-culturing the isolates on Potato Dextrose Agar. The degree of antagonism was determined by measuring and comparing the radial growth of pathogen with the bio-agent against the control. Out of the five isolates tested against C. kahawae, three isolates Fusarium proliferetum, Penicillium and Fusarium ceraneasum significantly inhibited test pathogen growth at 60%, 55% and 45.45%, respectively. The other isolates, Fumigatus aspergillus and Chaetomium perithecia showed inhibition of growth at 40% and 18.18% respectively. It was concluded that there is potential of using fungi as bio control of the coffee berry disease.

Targeted Action and Molecular Interactions of Sarcin and Thionin With Aspergillosis Causing Aspergillus fumigatus

Fungal infections are more predominant in agricultural and clinical fields. Aspergillosis caused by Aspergillus fumigatus leads to respiratory failure in patients along with various illnesses. Due to the limitation of antifungal therapy and antifungal drugs, there is an emergence to develop efficient antifungal compounds from natural sources to cure and prevent fungal infections. The present study deals with the investigation of the mechanism of active compounds from our candidate agonist Aspergillus giganteus for aspergillosis. The integrity of treated Aspergillus fumigatus cell membrane and nuclear membrane was analyzed by determining the release of cellular materials. The antagonistic potential of antifungal compounds on the pathogen was confirmed by SEM analysis. The effective concentration of antifungal compounds (AFCs) was found to be 250µg/ml. The GC-MS profiling has revealed the bioactive metabolites responsible for the antagonistic nature of Aspergillus giganteus. The bioavailability and toxicological properties of pathogenesis related proteins have proved the efficiency of pharmacokinetic properties of selected compounds. Interaction of sarcin, thionin, chitinase and its derivatives from Aspergillus giganteus with the virulence proteins of UDP-N-acetylglucosamine pyrophosphorylase, N-myristoyl transferase and Chitinase have proved the druggable nature of the antifungal compounds.

Bioefficacy of microbial antagonists against Zymoseptoria tritici on wheat

From our previous research of bio-control agents of the wheat pathogen Zymoseptoria tritici as an alternative to chemical control, one strain of Bacillus amyloliquefaciens and one strain of Trichoderma harzianum showed high antagonistic potential in vitro and in vivo as a foliar treatment on potted plants under greenhouse. The present work aimed to evaluate the antagonistic potential of these two strains of microorganisms in seed treatment. The results obtained showed that the two antagonists can reduce the severity of the disease assessed at three growth stages of the two wheat cultivars. B. amyloliquefaciens I3 reduced the severity of septoria leaf blotch by 56% and 58% compared to the checks on Aguilal and Karim respectively at the flag leaf stage, while in the case of T. harzianum A, this rate was 54% on Aguilal and 55% on Karim. These results suggest that the antagonistic potential is due to a distant mechanism of action such as induced systemic resistance. The viability tests of the two antagonists on coated seeds stored at 4 °C showed that they were viable after twelve months of conservation and preserved their antagonistic potential against Z. tritici.

Discovery of Three Novel Cytospora Species in Thailand and Their Antagonistic Potential

During an ongoing research survey of saprobic fungi in Thailand, four coelomycetous strains were isolated from decaying leaves in Chiang Mai and Phitsanulok Provinces. Morphological characteristics demonstrated that these taxa are typical of Cytospora in forming multi-loculate, entostromatic conidiomata, branched or unbranched conidiophores, with enteroblastic, phialidic conidiogenous cells and hyaline, allantoid, aseptate conidia. Multiloci phylogeny of ITS, LSU, ACT, RPB2, TEF1-α and TUB2 confirmed these taxa are distinct new species in Cytospora in Cytosporaceae (Diaporthales, Sordariomycetes), viz., Cytospora chiangmaiensis, C. phitsanulokensis and C. shoreae. Cytospora chiangmaiensis has a close phylogenetic relationship with C. shoreae, while C. phitsanulokensis is sister to C. acaciae. These three novel species were also preliminary screened for their antagonistic activity against five plant pathogenic fungi: Colletotrichumfructicola, Co. siamense, Co. artocarpicola, Co. viniferum and Fusarium sambucinum. Cytospora shoreae and C. phitsanulokensis showed >60% inhibition against Co. viniferum and F. sambucinum, while C. chiangmaiensis had moderate inhibition activity against all pathogens.

Probiotic Characteristics and Anti-inflammatory Properties of an Indian Indigenous Lactobacillus plantarum against Pathogenic Salmonella Typhimurium

Probiotic should be well characterized for any preventive and therapeutic application. Studies have reported that the population specific indigenous probiotics are more effective. Huge number of probiotics are available globally but indigenous Indian probiotic candidates are limited. Therefore, a study was conducted to evaluate probiotic characteristics and anti-inflammatory properties of an Indian indigenous Lactobacillus plantarum (Lp1) – (NCBI accession no- MN386242) against gastrointestinal (GI) pathogen Salmonella Typhimurium (ST) using Caco-2 cell lines. Anti-inflammatory properties were assessed by evaluating the expression of Immunoglobulins (IgA, IgG) receptors, Toll Like Receptors (TLR2, TLR4) and cytokine (IL10, IL-8, IL17 and IL23) using flowcytometry and Real Time-PCR. Lp1 showed good adhesion and ability to survive in high acidic and bile conditions of the gut. Lp1 demonstrated antagonistic potential against GI pathogens and modulated pro and anti-inflammatory cytokines expression significantly. Observed result indicated that this indigenous Lp1 is a good probiotic candidate with anti-inflammatory potential and can be evaluated further clinically for the treatment or prevention of salmonellosis and other GI inflammatory disorders.

Assessment of postharvest soil fungal population with special reference to Trichoderma in eggplants

The research work was done to assess the postharvest soil fungal population and to find out the relation between population dynamics of Trichoderma and soil borne disease of 41 eggplant cultivars. Soil samples collected from IPM lab germplasm maintenance field at post-harvest stage were analyzed for microbes in dilution plate technique. Fungal colonies appeared in each plate were counted and made their average. Incidence and severity of Fusarium wilt and Sclerotium collar rot in the plot of 41 eggplant varieties were recorded at flowering-fruiting stage. The highest total soil fungal population was estimated from the plot soil of eggplant var. Singnath S (IPM- 42) that was 40.75×104. The var. Bijoy had the lowest fungal population that was 7.5×104. A comparison between Trichoderma population and other fungal population was made. Different eggplant cultivars had variation in the population of two important soil fungi- Trichoderma and Fusarium. The total populations of Trichoderma and Fusarium in the plot soil of 41 eggplant varieties were 129.75 and 348.75 × 104 per gram of soil, respectively. The average number of colonies of Trichoderma varied with the range (1-8.25) per plate. Fusarium varied with the range from (2-22.50). In 20 important eggplant varieties out of 41, both Fusarium wilt and Sclerotium collar rot incidence ranged between 0.00 to 40.00%. The variety Puta begun had the highest incidence of Fusarium wilt with the highest soil population of Fusarium oxysporum against the absence of Trichoderma harzianum. The disease incidence at flowering-fruiting stage was negatively correlated with the population of Trichoderma. Disease severity decreased with the increase in Trichoderma population. Increase of Trichoderma population, decreased the population of other fungi (Fusarium oxysporum and Sclerotium rolfsii). These results are clearly indicating that Trichoderma might have the antagonistic potential and might contribute to the reduction of incidence of soil-borne diseases. Progressive Agriculture 32 (1): 31-42, 2021