Antagonistic Fungi Research Articles

Chemical Fungicides and Antagonists as Potential Treatments for Ganoderma lucidum-Associated Basal Stem Rot in Mandarin Trees

Ganoderma lucidum causes basal stem rot disease in mandarin trees, resulting in a variety of symptoms including dieback, foliage discoloration, an unhealthy appearance and eventual tree declines or death. Prior to field application, it is imperative to assess the efficacy of newer molecules and possible potential antagonists through In vitro testing. In this study, ten chemical fungicides and four antagonists were evaluated for their effectiveness against G. lucidum using the poison food method and dual culture technique, respectively. Among the chemical fungicides tested, Copper oxychloride 50% WP (@3g/l), Fluxapyroxad 167 G/L + Pyraclostrobin 333 G/L SC (@0.6 g/l), and Metiram 55% + Pyroclostribin 5% WG (@1g/l) demonstrated the highest effectiveness, entirely suppressing (100%) pathogen growth. In the dual culture technique, the fungal antagonists Trichoderma harzianum (79.63%) and Trichoderma asperellum (77.57%) exhibited superior effectiveness compared to Pseudomonas fluorescence and Bacillus subtilis against G. lucidum. These findings highlight the efficacy of chemical fungicides and antagonists in treating G. lucidum-induced basal stem rot in mandarin trees.

Widespread fungal-bacterial competition for magnesium lowers bacterial susceptibility to polymyxin antibiotics.

Fungi and bacteria coexist in many polymicrobial communities, yet the molecular basis of their interactions remains poorly understood. Here, we show that the fungus Candida albicans sequesters essential magnesium ions from the bacterium Pseudomonas aeruginosa. To counteract fungal Mg2+ sequestration, P. aeruginosa expresses the Mg2+ transporter MgtA when Mg2+ levels are low. Thus, loss of MgtA specifically impairs P. aeruginosa in co-culture with C. albicans, but fitness can be restored by supplementing Mg2+. Using a panel of fungi and bacteria, we show that Mg2+ sequestration is a general mechanism of fungal antagonism against gram-negative bacteria. Mg2+ limitation enhances bacterial resistance to polymyxin antibiotics like colistin, which target gram-negative bacterial membranes. Indeed, experimental evolution reveals that P. aeruginosa evolves C. albicans-dependent colistin resistance via non-canonical means; antifungal treatment renders resistant bacteria colistin-sensitive. Our work suggests that fungal-bacterial competition could profoundly impact polymicrobial infection treatment with antibiotics of last resort.

Antagonistic activity of biocontrol agent Trichoderma spp. against Fusarium sp., the causal agent of Ananas comosus fruitlet rot

Pineapple (Ananas comosus) is a significant crop, with an annual production exceeding 25 million tons. However, fusariosis can severely impact its cultivation, a fungal disease that causes fruitlet rot and results in substantial yield losses. To decrease dependency on chemical control methods, biocontrol agents (BCAs) present a promising alternative. Among these, Trichoderma species are noteworthy due to their diverse antagonistic mechanisms. The efficacy of each mechanism can be assessed through fungal confrontation assays. This study aimed to isolate, identify, and evaluate in-vitro nine Trichoderma spp. strains as potential BCAs against Fusarium sp. associated with pineapple fruitlet rot. The antagonistic fungi were isolated from rhizosphere soils in both open-field and greenhouse pineapple farms in Misiones province, Argentina. Identification of the fungi required both morphologic and genetic data. In the in-vitro assays, the capabilities for direct competition for substratum, production of metabolites, and mycoparasitism were evaluated. The results indicated that isolates T. harzianum TC7, T. harzianum TC9, T. asperellum TU3, and T. asperellum TU4 had statistically superior inhibitory effects against Fusarium sp. These isolates can be potentially used in formulating natural fungicides to reduce pineapple fruitlet rot caused by Fusarium, promoting sustainable production practices. Keywords: pineapple, confrontation, mycoparasitism, metabolites, ITS region

Antagonistic activity of biocontrol agent Trichoderma spp. against Fusarium sp., the causal agent of Ananas comosus fruitlet rot

Pineapple (Ananas comosus) is a significant crop, with an annual production exceeding 25 million tons. However, fusariosis can severely impact its cultivation, a fungal disease that causes fruitlet rot and results in substantial yield losses. To decrease dependency on chemical control methods, biocontrol agents (BCAs) present a promising alternative. Among these, Trichoderma species are noteworthy due to their diverse antagonistic mechanisms. The efficacy of each mechanism can be assessed through fungal confrontation assays. This study aimed to isolate, identify, and evaluate in-vitro nine Trichoderma spp. strains as potential BCAs against Fusarium sp. associated with pineapple fruitlet rot. The antagonistic fungi were isolated from rhizosphere soils in both open-field and greenhouse pineapple farms in Misiones province, Argentina. Identification of the fungi required both morphologic and genetic data. In the in-vitro assays, the capabilities for direct competition for substratum, production of metabolites, and mycoparasitism were evaluated. The results indicated that isolates T. harzianum TC7, T. harzianum TC9, T. asperellum TU3, and T. asperellum TU4 had statistically superior inhibitory effects against Fusarium sp. These isolates can be potentially used in formulating natural fungicides to reduce pineapple fruitlet rot caused by Fusarium, promoting sustainable production practices. Keywords: pineapple, confrontation, mycoparasitism, metabolites, ITS region

Antagonist Test of Trichoderma sp and Gliocladium sp Againts Fungal Pathogens That Cause Diseases on Tomato Plant

Tomatoes (Solanum lycopersicum) are one of the widely cultivated crops consumed by people worldwide, including Indonesia. Tomato farming often faces various challenges that result in reduced tomato productivity. One of the challenges is the presence of diseases that affect tomatoes, leading to crop failure for farmers. Some important diseases that commonly affect tomato plants include Fusarium wilt and anthracnose. Most farmer use chemical fungicides to control the diseases. These methods have greater negative impacts on both plants and the surrounding environment. One alternative control technique that can be used is the use of biological agents with antagonistic properties, such as Trichoderma sp. and Gliocladium sp. This research aims to assess antagonistic abilities of endophytic fungi Trichoderma sp. and Gliocladium sp. againts the pathogens responsible for suppresing the growth of these disease-causing phatogens in tomato plants. in the Laboratory of Plant Pest and Disease Science, OECF Building, Faculty of Agriculture, Universitas Mulawarman. The experiment was designed using a completely randomized single-factor design with four treatments and five replications. The data obtained were analyzed using Analysis of Variance and the least significant difference test at a 5% significance level. The research results indicate that the antagonistic tests of Trichoderma sp. and Gliocladium sp. in vitro significantly differ againts the pathogenic fungi Fusarium sp. and Colletotrichum sp. Furthermore, it was found that the antagonistic fungus Gliocladium sp. is the best fungus capable of suppressing the growth of important pathogenic fungi in tomato plants.Keyword: Gliocladium sp., Trichoderma sp., Fusarium sp., Colletotrichum sp. and Tomato (Solanum lycopersicum)

Selection and analysis of the characteristics of Lactiplantibacillus plantarum with antifungal activity

Phytophthora drechsleri is a prevalent spoilage-associated organism found in fruits and vegetables that causes serious economic loss and is a public health concern. Lactiplantibacillus plantarum is one of the most promising candidates for use in food as a fungal antagonist and biodetoxification agent. In this study, 347 of L. plantarum strains were preliminarily evaluated for antifungal activity against P. drechsleri Tucker. Only 5.48% of the L.plantarum strains tested exerted strong antagonism against P. drechsleri Tucker. L. plantarum IMAU70087 showed the greatest inhibitory activity and exhibited broad antifungal activity against seven test mold species. Moreover, the cell-free supernatant (CFS) of IMAU70087 exhibited strong thermostability and protease resistance. The potential antifungal metabolites were identified in IMAU70087 CFS by UPLC/QTOF/MS metabolomics analysis. These metabolites were mainly organic acids, some of which exhibited potential antifungal properties. This study provided valuable insights into the potential of IMAU70087 as a fungal inhibitor for enhancing food preservation.

Endophytic Fungi Inoculation Reduces Ramulosis Severity in Gossypium hirsutum Plants.

Biotic stress in cotton plants caused by the phytopathogenic fungus Colletotrichum gossypii var. cephalosporioides triggers symptoms of ramulosis, a disease characterized by necrotic spots on young leaves, followed by death of the affected branch's apical meristem, plant growth paralysis, and stimulation of lateral bud production. Severe cases of ramulosis can cause up to 85% yield losses in cotton plantations. Currently, this disease is controlled exclusively by using fungicides. However, few studies have focused on biological alternatives for mitigating the effects of contamination by C. gossypii var. cephalosporioides on cotton plants. Thus, the hypothesis raised is that endophytic fungi isolated from an Arecaceae species (Butia purpurascens), endemic to the Cerrado biome, have the potential to reduce physiological damage caused by ramulosis, decreasing its severity in these plants. This hypothesis was tested using plants grown from seeds contaminated with the pathogen and inoculated with strains of Gibberella moniliformis (BP10EF), Hamigera insecticola (BP33EF), Codinaeopsis sp. (BP328EF), G. moniliformis (BP335EF), and Aspergillus sp. (BP340EF). C. gossypii var. cephalosporioides is a leaf pathogen; thus, the evaluations were focused on leaf parameters: gas exchange, chlorophyll a fluorescence, and oxidative metabolism. The hypothesis that inoculation with endophytic strains can mitigate physiological and photochemical damage caused by ramulosis in cotton was confirmed, as the fungi improved plant growth and stomatal index and density, increased net photosynthetic rate (A) and carboxylation efficiency (A/Ci), and decreased photochemical stress (ABS/RC and DI0/RC) and oxidative stress by reducing enzyme activity (CAT, SOD, and APX) and the synthesis of malondialdehyde (MDA). Control plants developed leaves with a low adaxial stomatal index and density to reduce colonization of leaf tissues by C. gossypii var. cephalosporioides due to the absence of fungal antagonism. The Codinaeopsis sp. strain BP328EF can efficiently inhibit C. gossypii var. cephalosporioides in vitro (81.11% relative inhibition), improve gas exchange parameters, reduce photochemical stress of chlorophyll-a, and decrease lipid peroxidation in attacked leaves. Thus, BP328EF should be further evaluated for its potential effect as a biological alternative for enhancing the resistance of G. hirsutum plants and minimizing yield losses caused by C. gossypii var. cephalosporioides.

Determination of biotechnological potential of poultry litter isolated bacteria

Poultry litter is composed of residues from industrial wood processing, serving as a bed for the animals. It has also been widely used as an agricultural biofertilizer, increasing its economic importance. Few studies report the microbiological composition of this material or its biotechnological potential, which was the objective of this study. The microbiological composition was obtained by 16sRNA genetic characterization, as well as, phosphate solubilization capacity, indole-3-acetic acid (IAA) production, fungal antagonism, and enzymatic capacity. As a result, 67 isolates were obtained, of which 30 were taxonomically positioned and 27 were biochemically characterized. The microbiota genera consisted of Staphylococcus (17%), Brevibacillus (27%), Bacillus (37%), Mammaliicoccus (7%), Isoptericola, Microbacterium, and Oxalicibacterium (3.5% each). None of the isolates presented phosphate solubilization capacity. Regarding IAA production, UFPRCA19 showed the highest IAA content (16.60 µg.mg-1 protein). Eleven isolates were positive for antagonism with Aspergillus spp. and 25 for Trichoderma spp. Activity of proteases, caseinases, lipases, amylases, and cellulases were observed with the relative frequencies of 59%, 29%, 11%, 32%, 18%, and 21%. IAA and enzyme-producing bacteria as well as fungal antagonism were found among the isolates. Among all the isolated genera, Bacillus for synthesizing IAA and commercial enzymes becomes an interesting source for biotechnological purposes.

In vitro study of Trichoderma isolates – potential antagonists of Sclerotinia sclerotiorum and other soil pathogens causing root and stem rots on pepper (Capsicum annuum L.)

White mold Sclerotinia sclerotiorum (Lib.) de Bary is a potentially serious disease of pepper (Capsicum annuum L.) grown in unheated greenhouses. Control of Sclerotinia sclerotiorum is difficult due to lack of Capsicum spp. resistance towards this pathogen. Currently, among the registered fungicides there is none that can combat this pepper disease. The isolation and selection of local strains of antagonistic microbes is part of the strategy to combat pathogens by means of alternative methods. In vitro studies have been carried out on soil isolates of Trichoderma spp. regarding their antagonistic activity on the pathogen Sclerotinia sclerotiorum. All isolates were found to have a higher ability to compete with the phytopathogen for the food substrate. The competitive ability coefficient of Trichoderma spp. isolates varies widely – from 1.2 to 11. Among them, an isolate with pronounced antagonistic activity and a competitive ability coefficient of 10.8 stands out. The isolated fungus was identified as Trichoderma viride based on the cultural and morphological characteristics. The isolated strain was found to have high in vitro antagonistic activity not only against Sclerotinia sclerotiorum but also against various pathogens causing root and stem rot of pepper such as Botrytis cinerea, Verticillium dahliae and Rhizoctonia solani. The results of the current study showed that Trichoderma viride (Trv) has the potential to be used for production of biopreparation intended to control Sclerotinia sclerotiorum and other soil-borne pathogens in greenhouses. Keywords: antagonistic fungi, in vitro screening, antifungal activity, biological control, white mold, Capsicum annuum

The porcine skin microbiome exhibits broad fungal antagonism

The skin and its microbiome function to protect the host from pathogen colonization and environmental stressors. In this study, using the Wisconsin Miniature Swine™ model, we characterize the porcine skin fungal and bacterial microbiomes, identify bacterial isolates displaying antifungal activity, and use whole-genome sequencing to identify biosynthetic gene clusters encoding for secondary metabolites that may be responsible for the antagonistic effects on fungi. Through this comprehensive approach of paired microbiome sequencing with culturomics, we report the discovery of novel species of Corynebacterium and Rothia. Further, this study represents the first comprehensive evaluation of the porcine skin mycobiome and the evaluation of bacterial-fungal interactions on this surface. Several diverse bacterial isolates exhibit potent antifungal properties against opportunistic fungal pathogens in vitro. Genomic analysis of inhibitory species revealed a diverse repertoire of uncharacterized biosynthetic gene clusters suggesting a reservoir of novel chemical and biological diversity. Collectively, the porcine skin microbiome represents a potential unique source of novel antifungals.

Культуральные признаки и рост на сложных жидких питательных средах перспективного грибного штамма антагониста М-24 Penicillium sp. возбудителя фомоза подсолнечника

A microbiological method decreasing harmfulness of Phoma rot on sunflower, which is one of the prevailing disease in all regions of crop cultivation, is developed at the V.S. Pustovoit All-Russian Research Institute of Oil Crops. The cultural traits of antagonist fungus of phoma pathogen on sunflower М-24 Penicillium sp. on three agar media and strain growth on four complicated liquid nutrient media were studied at surface cultivation of a strainproducer to develop elements of technological regimen for production of microbiopreparations in a preparative form wettable powder. On the tenth days of cultivation at +25 °С temperature, strong growth of the fungus with abundant conidial sporulation and maximal diameter of a colony was noted on the agar medium by Rudakov. The medium by Rudakov is stated as optimal among complicated liquid nutrient media. In ten days of the surface cultivation, a thick folded mycelial film with an abundant sporulation was formed on this medium as well as maximal weight of a dry mycelium – 1.44 g per 100 ml of nutrient medium vs. 0.20–1.39 g on the other media.

Antagonistic activity of Trichoderma sp. against pathogens in the leaves of Allium ascalonicum L.

Pathogenic fungi pose constraints and reduce shallot production. Trichoderma sp. is an antagonistic fungus capable of controlling pathogen growth in shallots. The aim of this study was to determine the characteristics of Trichoderma sp. and pathogens in shallots and to assess the antagonistic ability of Trichoderma sp. against shallot pathogens (Allium ascalonicum L.). Trichoderma sp. and shallot pathogens were isolated using a serial dilution agar plate method using potato dextrose agar medium with 7-day incubation. The antagonistic activity of Trichoderma sp. against shallot pathogens was evaluated based on the dual culture method. In this study, we successfully isolated Trichoderma harzianum from the shallot leaf and its root systems. Moreover, four morphologically distinctive pathogens from shallot roots and leaves were successfully isolated (l Aspergillus sp., Colletotrichum sp., Phytium sp. and Penicillium sp. T. harzianum was found to have the ability to inhibit 23.45% growth of Aspergillus sp, 26.19% growth of Colletotrichum sp., 75.40% growth of Phytium sp., and 40.38% growth of Penicillium sp. In conclusion, the isolated T. harzianum had a strong antagonistic activity against some pathogens in the shallot, but the activity was weak against some others.

Effectiveness of sod and humus soil maintenance and biologized protection in intensive apple orchards (Malus domestica Borkh.) in the south of Russia

Application of intensive technologies in horticulture with a high mechanical and chemical load on soils and fruit plants leads to deterioration of soil properties, environmental pollution, and development of resistance among pathogens and phytophages. In this study, we aim to developing a biologized technology for apple tree cultivation using a sod and humus system of inter-row maintenance and biopreparations based on active strains of microorganisms, entomoacariphages, and pheromones. The research was conducted in 2019-2023 in intensive apple orchards of the central plain-steppe region of Crimea by the methods conventionally used in soil science, agrochemistry, horticulture, and plant protection. The use of a mixture of cereal-legume grasses in combination with microbiological fertilizers based on nitrogen-fixing microorganisms was found to increase apple yields by 11–12 t/ha, or 64 % compared to the control, by increasing the number of fruits and the average weight of one fruit. A positive balance of nutrition elements in soil with an intensity of 135-270 % was established. The efficiency of controlling the number of phytophages and pathogen harmfulness through the integrated use of biological and biotechnical methods was shown. Thus, the “attract-and-kill” method for Cydia pomonella L. pheromones demonstrated a 98 % efficiency along with a reduction in pesticide load to 7.7 kg/ha season by the preparation. Release of phitoseiid mites for control of tetranychus mites by the method of seasonal colonization provides for a reduction and retention of phytophagous population at the economic threshold of harmfulness during the entire vegetation period. The use of fungicides based on pathogenic bacteria of the Bacillus genus and antagonist fungi of the Trichoderma genus against scab is eff ective only in the years unfavorable for the development of the disease. The results obtained form the basis for a biologized resource-saving technology for exploitation of intensive apple orchards. This technology contributes to increased soil fertility, reduced chemical and pesticide load, and increased productivity of horticultural agrocenosis under the conditions of the Crimea and southern Russia.

Fusarium fujikuroi as a potential biocontrol agent of the parasitic weed Phelipanche aegyptiaca in tomato

AbstractPhelipanche aegyptiaca (Pers.) Pomel, commonly known as Egyptian broomrape, is an obligate root parasite, infesting solanaceous crops mainly in Mediterranean countries. Certain antagonistic fungi could be effectively used as a biocontrol agent for this parasitic plant. In this study, three fungal isolates (F1, F2 and F3) were obtained from P. aegyptiaca seeds covered with mycelium. The isolates were characterized based on morphological features and ITS and TEF sequence analysis. They were classified as belonging to Fusarium fujikuroi with a sequence similarity of 99.80% and 100%, respectively. The pathogenicity of the isolates on P. aegyptiaca and tomato were determined. In a P. aegyptiaca seed assay, all isolates allowed seed germination with delayed radicle development. Disease severity among the isolates ranged from 40%–70% on the basis of radicle necrotic area. The F1 isolate caused more than 40% disease on the spiders and tubercles in a polyethylene bag assay. The average of the total of spider and tubercle mortality caused by the F1 isolate was 63.5% at 9 days after inoculation. Moreover, the F1 isolate was considered non‐pathogen on tomato with 6.66% disease severity after root inoculation. To the best of our knowledge, this is the first report of F. fujikuroi on P. aegyptiaca seed. Pending further development, the F1 isolate could have potential for the biocontrol of P. aegyptiaca in the future.

Antifungal potential of volatiles produced by Aspergillus neoniger F14 against Ganoderma boninense

Ganoderma boninense Pat. is a fungal pathogen that primarily afflicts oil palm, leading to decreased palm oil yield and significant economic losses. The recent focus on biocontrol agents producing acids and volatile compounds has gained momentum due to their straightforward synthesis and ease of interaction with the phytopathogen. This research is a component of a project aimed at exploring the local biodiversity of antagonistic fungi in the oil palm plantation environment, with a specific focus on volatile organic compounds (VOCs) detected using Gas Chromatography-Mass Spectrometry (GC-MS). Isolate F14, a collection in the Laboratory of Applied Microbiology, BRIN, Indonesia was identified as Aspergillus neoniger, a novel report as a soil-originating fungal community in Indonesian oil palm plantations. VOC profiling using GC-MS revealed five dominant compounds namely (Z)-9-Tricosene, 1,2,3,4,5-Pentamethylcyclopentane, Dihexyl carbonate, Pentadecane, and Tridecyl laurate. Based on aromatogram disc tests against G. boninense colonies, it was determined that VOCs from A. neoniger F14 inhibited growth by 48% on the fifth day. The findings of this study contribute supportive information for further investigations into VOCs produced by other local antagonistic isolates against G. boninense.

Mutualistic and antagonistic phyllosphere fungi contribute to plant recruitment in natural communities

Abstract Phyllosphere fungal communities participate in multiple ecological functions (litter decomposition, disease‐causing, plant defence). However, there is a lack of knowledge on whether and how these functions contribute to plant community dynamics under natural conditions. One of the aspects of plant dynamics in which these fungi can most clearly affect is recruitment, since the success of newly germinated plants can be seriously compromised by pathogenic activity or the absence of mutualistic interactions. To determine the relationship between phyllosphere fungal communities and plant recruitment, we combined published information on the frequency of plant–plant recruitment interactions and phyllosphere fungal communities in 38 woody species from two mixed forests in southern Spain. Our results indicate that phyllosphere pathogens and saprotrophs have a negative effect on canopy–recruit interactions, while epiphytic fungi have a positive effect. Additionally, the presence of canopy species hosting high richness of epiphytes or counting with a high diversity of saprotrophic fungi favours the formation of an abundant sapling bank. Synthesis. Our results suggest that phyllosphere fungi play a relevant role in the assembly of the sapling bank in forest communities, thus, potentially influencing plant community dynamics. Beyond the well‐known negative effect of pathogenic fungi on recruitment, our results show the mutualistic effect of fungal epiphytes and a dual role of saprotrophs as antagonistic, decreasing recruitment of certain species, or mutualistic, enhancing recruitment in the sapling bank.

Characterization of Bacillus amyloliquefaciens PM415 as a potential bio-preserving probiotic.

Animal feed is vulnerable to fungal infections, and the use of bio-preserving probiotics has received increasing attention. In contrast to Lactobacillus and Bifidobacteria spp., fewer Bacillus spp. have been recognized as antifungal probiotics. Therefore, our objective was to screen antifungal strains and provide more Bacillus candidates to bridge this gap. Here, we screened 56 bacterial strains for cyclic lipopeptide genes and conducted an antifungal assay with Aspergillus niger as a representative fungus. We found that a Bacillus strain Bacillus amyloliquefaciens PM415, isolated from pigeon manure, exhibited the highest fungal inhibition activity as demonstrated by the confrontation assay and morphological observation under scanning electron microscope (SEM). Preliminary safety assessment and probiotic characterization revealed its non-pathogenic feature and stress tolerance capability. Whole genome sequencing of Bacillus amyloliquefaciens PM415 revealed a genome size of 4.16 Mbp and 84 housekeeping genes thereof were used for phylogenetic analysis showing that it is most closely related to Bacillus amyloliquefaciens LFB112. The in silico analysis further supported its non-pathogenic feature at the genomic level and revealed potential biosynthetic gene clusters responsible for its antifungal property. RNA-seq analysis revealed genome-wide changes in transportation, amino acid metabolism, non-ribosomal peptides (NRPs) biosynthesis and glycan degradation during fungal antagonism. Our results suggest that Bacillus amyloliquefaciens PM415 is a safe and effective probiotic strain that can prevent fungal growth in animal feeds.

Unveiling the Biocontrol Potential of Rhizoplane Bacillus Species against Sugarcane Fusarium Wilt through Biochemical and Molecular Analysis.

Biocontrol is regarded as a viable alternate technique for managing sugarcane wilt disease caused by Fusarium sacchari. Many fungal antagonists against F. sacchari, have been reported, but the potential of bacterial antagonists was explored to a limited extent, so the present study evaluated the antagonistic potential of rhizoplane Bacillus species and their mode of action. A total of twenty Bacillus isolates from the rhizoplane of commercially grown sugarcane varieties were isolated. The potential isolate SRB2 had shown inhibition of 52.30, 33.33, & 44.44% and SRB20 of 35.00, 33.15, & 36.85% in direct, indirect, and remote confrontation respectively against F. sacchari. The effective strains were identified as Bacillus inaquosorum strain SRB2 and B. vallismortis strain SRB20, by PCR amplification of 16S-23S intergenic region. The biochemical studies on various direct and indirect biocontrol mechanisms revealed the production of IAA, Protease, Cellulase, Siderophores, and P solubilization. The molecular analysis revealed the presence of antimicrobial peptides biosynthetic genes like fenD (Fengycin), bmyB (Bacyllomicin) ituC (Iturin) and spaS (Subtilin) which provided a competitive edge to these isolates compared to other Bacillus strains. Under greenhouse experiments, the sett bacterization with SRB2, significantly (P < 0.001) reduced the seedling mortality by > 70% followed by SRB20 in F. sacchari inoculated pots. The study revealed that the isolates B. inaquosorum SRB2 and B. vallismortis SRB20 can be used as potential bioagents against sugarcane Fusarium wilt.

Biocontrol Potential of Trichoderma Ghanense and Trichoderma Citrinoviride toward Pythium aphanidermatum.

Pythium-induced damping-off of cucumber is a major constraint to cucumber production in different parts of the world. Although chemical fungicides are used for managing this disease, they have many drawbacks to the environment. The ability of the antagonistic fungi isolated from the rhizosphere and endosphere of Dactyloctenium robecchii and Moraea sisyrinchium in the control of soilborne pathogen Pythium aphanidermatum was inspected. Native Trichoderma isolates, Trichoderma ghanense and Trichoderma citrinoviride, were isolated from plant stem and soil samples collected from Al-Seeb, Oman. Using a dual culture technique, the antagonistic activity of the fungal isolates against P. aphanidermatum was examined in vitro. Among Trichoderma isolates, T. ghanense was more efficient in restraining the mycelial growth of P. aphanidermatum, causing an inhibition percentage of 44.6%. Further, T. citrinoviride induced significantly lower cessation of P. aphanidermatum mycelial growth (31.3%). Microscopic and electrolyte leakage inspection of the pathogen mycelia depicted extreme morphological malformations in their mycelium, which can be attributed to the antifungal metabolites of antagonists. Greenhouse studies demonstrated the effectivity of T. ghanense in controlling Pythium damping-off of cucumber plants, where the number of surviving plants was over 90% when the biocontrol agents were used compared to 0 in the control plants. Furthermore, treatment of the plants with the antagonists promoted growth characteristics of plants compared to uninoculated plants. This included improvements in shoot and root lengths, leaf length and width, and dry weight. These findings suggest that T. ghanense and T. citrinoviride can be developed as alternatives to synthetic chemical fungicides to manage soilborne pathogens of cucumber. This research is also the first to clarify the biocontrol ability of T. citrinoviride and T. ghanense against cucumber damping-off caused by P. aphanidermatum.

Biocontrol of Cocoyam (Colocasia esculenta) Spoilage Fungi by Trichoderma harzianum collected from Rivers and Abia State, Nigeria

Biocontrol is a technique of controlling pests, whether pest animals such as insects and mites, weeds, or pathogens affecting animals or plants by using other organisms. Hence, the objective of this paper as to investigate the biocontrol of Cocoyam (Colocasia esculenta) spoilage fungi by Trichoderma harzianum collected from Rivers and Abia States in Nigeria using standard microbiological methods. The results obtained show that the fungi isolated were Aspergillus flavus, Aspergillus niger, Mucor sp and Penicillium and Trichorderma sp. Antagonistic fungi was identified molecularly as Trichoderma harzianum strain A0H287. The inhibitory effect of the biological antagonist T. harzianum showed that it reduced the growth of A. niger by 50%, Mucor sp by 34.1%, Penicillium sp by 70% and A. flavus by 63.7%. The study showed that the biological antagonist, Trichoderma showed effectiveness in the reduction of the growth of majority of the pathogenic fungi and could be recommended as alternative to chemical fungicides.