Use Of Biocontrol Agents Research Articles

Efficacy of biocontrol agents against Sclerospora graminicola causing downy mildew in fodder pearl millet

Downy mildew incited by Sclerospora graminicola is the main hurdle in the successful cultivation of pearl millet and is capable of causing more than 60% losses in terms of grain and fodder yields. The disease could be managed by fungicide applications but due to several associated environmental and health-related issues, there was a necessity to formulate some eco-friendly measures for downy mildew management. Thus attempts were made to find out the usefulness of three biocontrol agents (Bacillus subtilis, Pseudomonas fluorescens and Trichoderma viride) and two fungicides (mancozeb 64% + metalaxyl 4% and metalaxyl) under field conditions for three seasons (2017-2019) against downy mildew. The least downy mildew incidence (14.37%) was observed with seed treatment + foliar spray of B. subtilis as compared to untreated control (31.30%) with 54.10% disease reduction followed by seed treatment + foliar spray of P. fluorescens (17.58% disease incidence) with 43.82% disease control. The same treatments were significantly superior over others in increasing the green fodder yield by 56.59 and 40.79% respectively. Another treatment proven effective was seed treatment + two foliar sprays of T. viride which provided more than 43% reduction in downy mildew incidence as compared to chemical check which provided 30% disease control and increase in green fodder yield. These findings advocated the potential use of biocontrol agents against downy mildew of pearl millet in an eco-friendly manner.

Use of Entomopathogenic Nematodes for the Management of Banana Rhizome Weevil (Cosmopolites sordidus): A Review

Banana is an important fruit crop which is grown in tropical and subtropical parts of the world. Banana production is inhibited by various insect pests. Though chemical insecticides are recommended for control of these pests, use of biocontrol agents are alternative method .One of the biocontrol agents is the entomopathogenic nematodes (EPNs). This review finds the work of some of the successful EPN species or strains from different geographical locations that may affect practical bio control of banana rhizome weevil, a major pest of banana. Emphasis is made on roles of EPNs in reducing banana rhizome weevil (Cosmopolites sordidus) and directions of future research in biocontrol programme are presented.

In vitro bioefficacy of Trichoderma species against two Botryosphaeriaceae fungi causing Eucalyptus stem canker disease in Ethiopia

Phytopathogenic fungi, which are leading to significant economic and production losses, pose a serious threat to global forestry. Field surveys were carried out on Eucalyptus trees in Ethiopia between 2019/20 and 2020/21. The E. camaldulensis predominantly grew in the surveyed fields and was severely affected by progressive stem canker disease. The diseased stems and branches exhibiting symptoms were collected, and the Lasiodiplodia theobromae and Neofusicoccum parvum fungal pathogens were identified via morphological and DNA sequence analyses of ITS1 and ITS2 from rDNA. The objective of this research was to assess the in vitro growth inhibition potential of Trichoderma species against Lasiodiplodia theobromae and Neofusicoccum parvum fungal species. Researchers are now exploring alternate eco-friendly management strategies due to the hazardous effects chemical fungicides have on human and environmental health. The use of biocontrol agents, such as Trichoderma species, is one of the potential approaches employed today. The antagonistic activities of Trichoderma asperellum (T4), Trichoderma asperellum (T5), Trichoderma atroviride (T1), Trichoderma atroviride (T11), Trichoderma longibrachiatum (T3), and Trichoderma longibrachiatum (T31) were tested in vitro against Lasiodiplodia theobromae and Neofusicoccum parvum that cause canker disease symptoms in E. camaldulensis. In all antagonism tests, T. asperellum and T. longibrachiatum effectively inhibited the growth of L. theobromae and N. parvum. This implies that the Trichoderma species could be useful to control E. camaldulensis canker disease.

The Exploitation of Microbial Antagonists against Postharvest Plant Pathogens.

Postharvest disease management is vital to increase the quality and productivity of crops. As part of crop disease protection, people used different agrochemicals and agricultural practices to manage postharvest diseases. However, the widespread use of agrochemicals in pest and disease control has detrimental effects on consumer health, the environment, and fruit quality. To date, different approaches are being used to manage postharvest diseases. The use of microorganisms to control postharvest disease is becoming an eco-friendly and environmentally sounds approach. There are many known and reported biocontrol agents, including bacteria, fungi, and actinomycetes. Nevertheless, despite the abundance of publications on biocontrol agents, the use of biocontrol in sustainable agriculture requires substantial research, effective adoption, and comprehension of the interactions between plants, pathogens, and the environment. To accomplish this, this review made an effort to locate and summarize earlier publications on the function of microbial biocontrol agents against postharvest crop diseases. Additionally, this review aims to investigate biocontrol mechanisms, their modes of operation, potential future applications for bioagents, as well as difficulties encountered during the commercialization process.

Parasitism Potential and Laboratory Rearing of Psyllaephagus sp., a Newly Discovered Parasitoid of Cacopsylla chinensis

Psyllaephagus sp. (Hymenoptera: Encyrtidae) is a newly recognized and important parasitoid of Cacopsylla chinensis (Yang and Li) (Hemiptera: Psyllidae), a pest of pear orchards. Its parasitism potential and rearing were studied in the laboratory. The studies showed that the most suitable hosts were fourth- and fifth-instar nymphs of pear psyllids (C. chinensis). The development duration of Psyllaephagus sp. females and males was 15.25 ± 0.37 and 13.57 ± 0.27 days when laying eggs in fourth-instar psyllid nymphs. The wasps did not survive longer than three days when they were fed only water, while they survived about an average of 20 days (23.20 ± 1.12 for females and 19.00 ± 0.80 for males) when fed 20% honey water. The provision of honey water could thus increase adult parasitoid longevity significantly. The lifetime fecundity of Psyllaephagus sp. females was 21.60 ± 0.88. Tests of parasitoid efficiency showed that the wasp’s functional response was Holling type II, with the number of hosts parasitized increasing with the host density to a maximum parasitism rate. The model suggested that a single Psyllaephagus sp. female could parasitize a maximum of 13.66 nymphs per day. The mutual interference of foraging Psyllaephagus sp. females occurred at high parasitoid densities. Psyllaephagus sp. has potential as a biocontrol agent for use against C. chinensis.

Efficacy of preharvest application of biocontrol agents against gray mold in grapevine.

The use of biocontrol agents (BCAs) represents a promising alternative to conventional methods for the management of gray mold in vineyards during the berry ripening stage. The main advantages of BCAs are the short preharvest interval and lack of chemical fungicide residues in wine. In this study, eight commercial BCAs (based on different Bacillus or Trichoderma species and strains, Aureobasidium pullulans, Metschnikowia fructicola, and Pythium oligandrum) and a reference fungicide (boscalid) were applied to a vineyard during berry ripening over three seasons to evaluate the dynamics over time in terms of their relative efficacies in gray mold control. At 1-13 days after application of BCAs to the berry surfaces in field conditions, the berries were collected and artificially inoculated with conidia of Botrytis cinerea under controlled laboratory conditions, and gray mold severity was observed after 7 days of incubation. Significant differences were observed in gray mold severity among years, according to the number of days the BCAs grew on the berry surface before B. cinerea inoculation, and the season by day interaction (altogether accounting for >80% of the experimental variance). The variability in BCA efficacy was closely related to the environmental conditions at the time of application and in the following days. Overall, the BCA efficacy increased with the degree days accumulated between BCA application in the vineyard and B. cinerea inoculation in the dry (no rain) periods (r = 0.914, P = 0.001). Rainfall and the associated drop in temperature caused a relevant reduction of BCA efficacy. These results demonstrate that BCAs are an effective alternative to conventional chemicals for the preharvest control of gray mold in vineyards. However, environmental conditions can considerably affect the BCA efficacy.

Fungi Associated with the Spoilage of Sweet Orange (Citrus sinensis) Fruits and their Management by Bio-Control Agents

Different Sweet Orange fruits (Citrus Sinensis) rot fungi were isolated from rotted fruits.These were Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus, Penicillium digitatum. During pathogenicity test two fungi Aspergillus niger and Penicillium digitatum were proved to be most pathogenic. The Aspergillus niger fungi during dual culture with Bacillus substilis, Bacillus substilis srtain2, Pseudomonas fluorescens, Pseudomonas aeruginosa , Bacillus methylotrophicus, Bacillus cereus, Bacillus aryabhattai and Streptomyces strain showed different level of inhibation zones. Bacillus cereus was the most effective and caused 71.5% inhibition and Pseudomonas aeruginosa was least 53.28% and others Bacillus substilis, Bacillus substilis srtain2, Pseudomonas fluorescens, Bacillus methylotrophicus , Bacillus aryabhattai ,and Streptomyces caused 68.05%, 64.00%, 70.25%, 59.37%, 57.75% and, 55.25%, respectively. Penicillium digitatum fungi during dual culture with Bacillus substilis, Bacillus substilis srtain2, Pseudomonas fluorescens, Pseudomonas aeruginosa , Bacillus methylotrophicus, Bacillus cereus, Bacillus aryabhattai and Streptomyces strain showed different level of inhibation zones. Bacillus cereus was the most effective and caused 69.25% inhabition and Pseudomonas aeruginosa was least 51.75% respectively. During experiment on fruits the most effective biocontrol agent Bacillus cereus and Streptomyces strain were tested on fruits and it was found that Bacillus cereus and Streptomyces strain were effectively control the rot by Aspergillus niger and showed data 49.45%, 43.55%. During experiment on fruits the most effective biocontrol agent Bacillus cereus and Streptomyces strain were tested on fruits and it was found that Bacillus cereus and Streptomyces strain were effectively control the rot by Penicillium digitatum and showed data (51.62%, 45.67%). Experiment were performed for protective and curative effects. During protective effect the two biocontrol agents Bacillus methylotrophicus and Bacillus cereus reduced the percentage rottenig by 64.74% and 57.52% respectively in case of Aspergillus niger and in case of Penicillium digitatum the effect of two Biocontrol agents Bacillus methylotrophicus and Bacillus cereus caused 59.37% and 54.63% respectively reducuction in decaying. During the Curative effect the two biocontrol agents Bacillus methylotrophicus and Bacillus cereus reduced the rottenig percentage 62.53% and 55.84% respectively in case of Aspergillus niger but in case of Penicillium digitatum the effect of the Biocontrol agents Bacillus methylotrophicus and Bacillus cereus caused 58.29% and 51.99% respectively reducuction in decaying. Use of Biocontrol agents as protective is better than the curative.

Additive Effect of the Composition of Endophytic Bacteria Bacillus subtilis on Systemic Resistance of Wheat against Greenbug Aphid Schizaphis graminum Due to Lipopeptides.

The use of biocontrol agents based on endophytic bacteria against phloem-feeding insects is limited by a lack of knowledge and understanding of the mechanism of action of the endophyte community that makes up the plant microbiome. In this work, the mechanisms of the additive action of endophytic strains B. subtilis 26D and B. subtilis 11VM on the resistance of bread spring wheat against greenbug aphid Schizaphis graminum, was studied. It was shown that B. subtilis 26D secreted lipopeptide surfactin and phytohormones cytokinins, and B. subtilis 11VM produced iturin and auxins into the cultivation medium. Both strains and their lipopeptide-rich fractions showed direct aphicidal activity against greenbug aphid. For the first time, it was shown that B. subtilis 26D and B. subtilis 11VM in the same manner, as well as their lipopeptide-rich fractions, activated the expression of salicylate- and ethylene-dependent PR genes, and influenced plant redox metabolism, which led to an increase in plant endurance against aphids. The composition of endophytic strains B. subtilis 26D + B. subtilis 11VM had an additive effect on plant resistance to aphids due to an increase in the number of endophytic bacterial cells, and, as well as due to the synergistic effect of their mixture of lipopeptides - surfactin + iturin, both on the aphid mortality and on the expression of PR1 and PR3 genes. All these factors can be the reason for the observed increase in the growth of plants affected by aphids under the influence of B. subtilis 26D and B. subtilis 11VM, individually and in composition. The study demonstrates the possibility of creating in the future an artificial composition to enhance plant microbiome with endophytic bacteria, which combines growth-promoting and plant immunity stimulating properties against phloem-feeding insects. This direction is one of the most promising approaches to green pesticide discovery in the future.

Interactions between Entomopathogenic Fungi and Entomopathogenic Nematodes.

Entomopathogenic fungi and entomopathogenic nematodes are globally distributed soil organisms capable of infecting and killing a vast variety of insects. Therefore, these organisms are frequently used as biocontrol agents in insect pest management. Both entomopathogenic fungi and nematodes share the soil environment and thus can infest and compete for the same insect host; however, natural co-infections are rarely found due to the cryptic soil environment. Our current knowledge on their interactions within hosts mainly comes from laboratory experiments. Because of the recent trend of combining biocontrol agents to increase their efficacy, many studies have focused on the co-application of different species of EPF and EPNs against various insect pests with variable outcomes ranging from synergistic effects and additive effects to antagonism. In addition, the effect on the development and reproduction of each pathogen varies from normal reproduction to exclusion, and generally the outcomes of the interactions are dependent on pathogen and host species, pathogen doses, and the timing of infection. The present review aims to summarize the current knowledge on the interactions of entomopathogenic fungi and nematodes within an insect host and to estimate the possible effects of the interactions on natural pathogen populations and on their use in biocontrol.

An Extensive Review of Strawberry (Fragaria×ananassa) Diseases and Integrated Management Approaches: Current Understanding and Future Directions

Strawberry production has increased by more than double in the past two decades. Meanwhile, it is also susceptible to various diseases which have become a limiting factor in its yield increment. Indiscriminate use of chemicals in the management of diseases has brought several adverse effects to the environment and human health. Thus, this review aims to present the different diseases of strawberries including their epidemiology, disease cycle, and symptoms. Moreover, the focus has been given to Integrated Management. More than ten dozen of literature including journal articles, books, websites, and organizational reports were thoroughly reviewed to get the related information. Botrytis grey mold rot, anthracnose, strawberry leaf spot, powdery mildew, and red stele are the major fungal diseases whereas angular leaf spot is the serious bacterial disease of strawberries. It is severely infected by viruses such as strawberry mottle virus and crinkling and vein banding virus. In addition to this nematode causes ring spots, root-knot, and root lesions on strawberries. Integrated disease management approaches should be adopted for effective and sustainable management. It may include cultural methods, physical methods, use of bio-control agents, botanical fungicides, and at last chemicals if the disease is severe.

Use of biosurfactants produced by Bacillus subtilis H1 and Pseudomonas aeruginosa PAO1 as a disinfectant and plant growth stimulation

Sustainable agriculture involves the maximum use of the resource potential of the earth, with the constant renewal of the fertility of the ecosystem. One method of transition to sustainable agriculture is the use of biological control agents, which include biosurfactants. We assessed the possibility of using crude biosurfactants obtained from Bacillus subtilis H1 and Pseudomonas aeruginosa PAO1 as dressing agents for untreated wheat seeds and the presence of seed germination stimulating properties. It was shown that crude rhamnolipids obtained from Pseudomonas aeruginosa PAO1 inhibited the area occupied by fungal mycelia at a concentration of 500 mg/l. Surfactin, derived from Bacillus subtilis H1, inhibited fungal growth at a concentration of 100 mg/L. Stimulation of germination of wheat seeds by 1.9 and 2 times was determined by rhamnolipid at a concentration of 500 mg/l and surfactin at a concentration of 100 mg/l for 168 hours of germination. The use of biocontrol agents is a promising method that can improve product quality while reducing the negative impact on the environment.

Isolation and in vitro screening of native Trichoderma isolates against economically important pathogens of Japanese Mint (Mentha arvensis)

Japanese mint (Mentha arvensis) is a common edible aromatic herb of considerable economic importance and the crop is reported to be infected by several fungal pathogens. As Mentha contains essential oil which is used in pharmaceutical industries, the use of biocontrol agents is considered as a potential eco-friendly component in plant disease management. Hence an investigation was conducted in the Department of Plant Pathology, RPCAU, Pusa, Bihar to evaluate native Trichoderma isolates against two economically important foliar pathogens of Japanese Mint (Mentha arvensis) i.e., Alternaria alternata and Curvularia lunata. Total 7 Trichoderma isolates were isolated from the rhizosphere of various medicinal plants and those were categorized based on their morphological characteristics. Initially, all Trichoderma isolates developed whitish mycelium which later differed from light to dark green in color and the growth rate ranged from 11.25 mm to 18.00 mm per day. During the evaluation of antagonistic activity, all the Trichoderma isolates significantly reduced the growth of Alternaria alternata and Curvularia lunata mycelia in vitro condition. Among the seven isolates, Tr6 recorded the highest inhibition of Alternaria alternata (65.66%) and Curvularia lunata (45.04%) followed by Tr3 which showed 57.00% and 40.32% mycelial growth inhibition of Alternaria alternata and Curvularia lunata respectively after 168 hours of incubation. Tr6 isolate also exhibited the highest biochemical activities viz., indole acetic acid, ammonia, and siderophore production. The results from the current investigation revealed that Tr6 isolate was found most potential in the suppression of pathogens growth as well as in the production of phyto stimulators. In future studies, this isolate can further be evaluated for successful management of diseases of Japanese mint (Mentha arvensis).

Endophytic Bacillus subtilis P10 from Prunus cerasifera as a biocontrol agent against tomato Verticillium wilt.

Endophytic bacteria serve key roles in the maintenance of plant health and growth. Few studies to date, however, have explored the antagonistic and plant growth-promoting (PGP) properties of Prunus cerasifera endophytes. To that end, we isolated endophytic bacteria from P. cerasifera tissue samples and used a dual culture plate assay to screen these microbes for antagonistic activity against Verticillium dahliae, Botryosphaeria dothidea, Fusarium oxysporum, F. graminearum, and F. moniliforme. Of the 36 strains of isolated bacteria, four (strains P1, P10, P16, and P20) exhibited antagonistic effects against all five model pathogens, and the P10 strain exhibited the strongest antagonistic to five pathogens. This P10 strain was then characterized in-depth via phenotypic assessments, physiological analyses, and 16s rDNA sequencing, revealing it to be a strain of Bacillus subtilis. Application of a P10 cell suspension (1×108 CFU/mL) significantly enhanced the seed germination and seedling growth of tomato in a greenhouse setting. This P10 strain further significantly suppressed tomato Verticillium wilt with much lower disease incidence and disease index scores being observed following P10 treatment relative to untreated plants in pot-based experiments. Tomato plants that had been treated with strain P10 also enhanced defense-related enzymes, peroxidase, superoxide dismutase, and catalase activity upon V. dahliae challenge relative to plants that had not been treated with this endophytic bacterium. The results revealed that the P10 bacterial strain has potential value as a biocontrol agent for use in the prevention of tomato Verticillium wilt.

Prodigiosin Pigmentinin Tenebrio molitor (Coleoptera:Tenebrionidae) Üzerindeki İnsektisidal Aktivitesi

Microorganisms and their metabolites have the potential to provide a sustainable alternative to chemical insecticides. Serratia marcescens is an entomopathogenic bacterium that produces hydrolytic enzymes and toxins. It also produces a red pigment called prodigiosin, which has a variety of biological properties. In this study, the prodigiosin pigment was extracted from S. marcescens Se9 isolate with acidified ethanol and concentrated using a rotary evaporator. The insecticidal potential on larval and adult stages of Tenebrio molitor was then investigated. It was found that the mortality rate of larvae exposed to the lowest concentration (125 ppm) of crude pigment was 5%, while the mortality rate of larvae exposed to the highest concentration (2000 ppm) was 68%. The LC50 value of the crude pigment for the larval stage was determined to be 924 ppm. On the other hand, even at the highest pigment concentration (2000 ppm), only 30% mortality was observed in adults. The LC50 value of the crude pigment for the adult stage was determined to be 4570 ppm. It was determined that the pigment had a toxic effect on the pest, but the larval stage was more sensitive than the adult stage. The study showed that prodigiosin pigment appears to be a promising biocontrol agent for use against T. molitor.

Characterization of the Mechanism of Action of Serratia rubidaea Mar61-01 against Botrytis cinerea in Strawberries.

Several bacterial strains belonging to Serratia spp. possess biocontrol capability, both against phytopathogens and human pathogenic species, thanks to the production of secondary metabolites, including as a red-pink, non-diffusible pigment, 2-methyl-3-pentyl-6-methoxyprodiginine (prodigiosin). Botrytis cinerea is the causal agent of gray mold, which is an economically relevant disease of many crops worldwide. Gray mold is normally controlled by chemical fungicides, but the environmental and health concerns about the overuse of pesticides call for environmentally friendly approaches, such as the use of biocontrol agents. In this study, the efficacy of a specific strain of Serratia rubidaea (Mar61-01) and its metabolite prodigiosin were assessed against B. cinerea under in vitro and in vivo conditions. This strain was effective against B. cinerea, and the effect of prodigiosin was confirmed under in vitro and in vivo conditions. The strain suppressed mycelial growth of B. cinerea (71.72%) in the dual-culture method. The volatile compounds produced by the strain inhibited mycelial growth and conidia germination of B. cinerea by 65.01% and 71.63%, respectively. Efficacy of prodigiosin produced by S. rubidaea Mar61-01 on mycelial biomass of B. cinerea was 94.15% at the highest concentration tested (420 µg/mL). The effect of prodigiosin on plant enzymes associated with induction of resistance was also studied, indicating that the activity of polyphenol oxidase (PPO), superoxide dismutase (SOD) and phenylalanine ammonia lyase (PAL) were increased when prodigiosin was added to the B. cinerea inoculum on strawberry fruits, while catalase (CAT) and peroxidase (POD) did not change. In addition, the volatile organic compounds (VOCs) produced by S. rubidaea Mar61-01 reduced mycelial growth and inhibited conidial germination of B. cinerea in vitro. The findings confirmed the relevant role of prodigiosin produced by S. rubidaea Mar61-01 in the biocontrol of B. cinerea of strawberries, but also indicate that there are multiple mechanisms of action, where the VOCs produced by the bacterium and the plant-defense reaction may contribute to the control of the phytopathogen. Serratia rubidaea Mar61-01 could be a suitable strain, both to enlarge our knowledge about the potential of Serratia as a biocontrol agent of B. cinerea and to develop new biofungicides to protect strawberries in post-harvest biocontrol.

Production of iturin A by Bacillus velezensis ND and its biological control characteristics.

Bacillus subtilis, as a biocontrol bacterium, possess a variety of biological functions and the capacity to control plant pathogens. Iturin A is a biosurfactant with broad-spectrum antifungal activity produced by fermentation of B. subtilis. In this study, the dynamic parameters of solid-state fermentation (SSF) and submerged fermentation (SMF) of Bacillus velezensis ND were compared, and a method for producing iturin A with a yield of 12.46 g/kg utilizing SSF was proposed. It has significant advantages over SMF and has the highest yield of all previously reported studies. B. velezensis ND also contains protease activity, cellulase activity, iron-carrying activity, the ability to synthesis 3-indoleacetic acid (IAA), fixation nitrogen, and degrade phosphorus. In cotton pot experiments, it can effectively increase cotton growth and minimize Verticillium wilt. This strain's superior fermentation efficiency, biological function, and biocontrol ability are sufficient to demonstrate its promise for the development and use of biocontrol agents.

Production of potato seed tubers under the effect of Trichoderma sp. and rhizobacteria in greenhouse conditions

Potato (Solanum tuberosum L.) is one of the main crops in the Andean region and due to environmental aspects, the use of biocontrol agents is considered a safe way to produce potato seed tubers.The objective of the study was to evaluate potato inoculation with Trichoderma sp. as a matrix and rhizobacteria Bacillus simplex and Azotobacter sp. on the growth of potato seedlings from in vitro culture, for the production of seed tubers in a greenhouse. The inoculation of microorganisms was carried out in pots, using five potato genotypes for processing. The inoculation treatments were: control, Trichoderma sp., Trichoderma sp. + Azotobacter sp., Trichoderma sp. + Bacillus simplex, Trichoderma sp. + B. simplex + Azotobacter sp. The potato genotypes were cv. Unica (CIP392797.22), cv. Bicentenaria, the advanced clones CIP 396311.1, CIP 399101.1, and the experimental clone UH-09 from the Universidad Nacional José Faustino Sánchez Carrión. A completely randomized design was used, under a factorial arrangement and comparisons between treatments were made at p<0.05. All inoculant treatments exceeded the control in number and weight of tubers per plant as well as in tuber size. Inoculations of Trichoderma sp. alone or with Azotobacter sp. increased plant height, number of leaves per plant and vegetative uniformity; inoculations with the Trichoderma sp. + B. simplex + Azotobacter sp. consortium, improved the dry weight of the foliage, number of shoots per plant and vegetative vigor. There were significant interactions between potato genotypes and inoculant treatments for plant uniformity, vegetative vigor, and the foliage's dry weight. Coinoculation with Trichoderma sp. and some bacterial strains promote the growth of in vitro potato seedlings, increasing the size and weight of the seed tubers and plant biomass, indicating an interrelation between fungi and bacteria that influence the production of potatoes in a greenhouse.

Antifungal Activity of Verticillin D Isolated from Clonostachys rosea EC28 against Alternaria burnsii and Sclerotium rolfsii

Alternaria leaf spot and white crown rot caused respectively by Alternaria sp and Sclerotium rolfsii are responsible for significant economic losses in tomato cultivation in Côte d'Ivoire. Chemical control of these diseases has its limits due to the harmful effects of synthetic fungicides on the environment and the health of farmers and populations. As a result, biological control through the use of biocontrol agents represents one of the alternative solutions. Clonostaschys rosea EC 28, a biocontrol agent is an endophyte fungus isolated from Ceiba pentandra, whose objective of this study was to show the antifungal properties of verticillin D produced by this fungus against A. burnsii and S. rolfsii. C. rosea EC 28 was cultured on rice medium and extracted with ethyl acetate. Open silica gel column chromatography of this crude extract led to the purification of two secondary metabolites that were identified by mass spectrometry and NMR as verticillin D and ergosterol. The activity in vitro antigerminative of A. burnsii spores and against growth mycelial growth of S. rolfsii of these molecules have been determined. Verticillin D inhibited A. burnsii spore germination and growth mycelial growth of S. rolfsii with respective MICs of 0.25 mg / mL and 5mg/ mL. Ergosterol n / A present none activity antifungal. These results provide a database for the use of Clonostachys rosea EC 28 as a potential biocontrol agent for two major tomato diseases in Ivory Coast.

Anti-Salmonella polyvinyl alcohol coating containing a virulent phage PBSE191 and its application on chicken eggshell

The use of antibiotics in the food industry is avoided due to the increase of antibiotic-resistant bacteria. Therefore, the bacteriophage is emerging as an alternative agent. Here, we characterized the Salmonella Enteritidis phage PBSE191 and applied it to a polyvinyl alcohol (PVA) film. Transmission electron microscopic analysis revealed that it belonged to the Caudoviricetes class, with an icosahedral head and flexible tails. The phage showed rapid and strong lytic activity within 1 h. It was active against a broad range of Salmonella isolates, including six serotypes. In 25 min, 99 % of the initial population was adsorbed to the bacterial cell surface. The phage was also applied to 10 % (w/v) PVA films and coatings, which were then characterized in terms of phage stability and antibacterial performance, both in vitro and in foods. The phage remained stable in the 10 % (w/v) PVA solution containing 20 % (w/w, based on PVA weight) sorbitol (PVAS20), indicating that the phage was stable under dry conditions and strongly released in the polymer. Furthermore, significant bacterial cell reduction (2.0 × 105 CFU/film within 2 h) was observed in the phage-containing PVAS20 films. In addition, the PBSE191-containing PVAS20 coating on the chicken eggshell surface showed significant anti-Salmonella efficiency (about 2 log CFU reduction) within 24 h. Overall, the PBSE191 phage possesses a high potential as a biocontrol agent for use as an additive, or as an active antibacterial packaging to improve food safety against Salmonella contamination.

Effect of Antagonistic Microorganisms on Fruit Colour Development and Sensory Properties of Papaya (Carica papaya) var. Red Lady

An experiment was conducted in the Department of Agricultural Microbiology and Post-Harvest Technology, COH, Bagalkot, Karnataka during the year 2017-2018 with intention of minimizing the post harvest diseases during storage by using ecofriendly approach that is use of biocontrol agents and their effects on fruit colour development and sensory parameters. A wide range of fungi, bacteria, yeast and actinomycetes can be used as antagonistic microorganisms against post-harvest pathogens in many horticulture produce. In the present experiment, five effective antagonistic microorganisms were assessed for their antifungal activity against Colletotrichum gleosporiodies, the causal agent of post-harvest Anthracnose disease of papaya fruits and fortheir effects on fruit development and sensory properties of papaya var. Red Lady. In the present experiment the papaya fruits treated with biocontrol agents and observed that, the papaya fruits treated with BCA5-Isolate No.10(T5) exhibited higher L*(56.53), a*(12.33), b*(43.60) colour values, higher carotene value (1.85 mg/100 g), total sugar content (11.6%) and good sensory scores for colour (8073), taste (8.6) and textue (9.03) at 9 days after storage under ambient storage condition followed by BCA-Isolate No.09(T4) and carbendazium at 0.1% for 5 min (T7). Treated on inoculated papaya fruits with C. gloeosporioides, T5 (BCA5 -Isolate No. 10) recorded higher L*(55.67), a*(11.61), b*(41.78) colour values, higher carotene value (1.42 mg/100 g), total sugar content (10.4%) and good sensory scores for colour (8.3), taste (8.13) and textue (8.73) at 9 days after storage under ambient storage condition followed by BCA4 -Isolate No.9 (T4) and carbendazium at 0.1% (T7). These two isolates identified in this experiment can be effectively used alternative to chemicals against anthracnose which were effective in fruit colour development and sensory parameters.