Good Biocontrol Agent Research Articles

Role of Rhizobacteria Associated with Diseased Tomato Plants towards their Response with Ralstonia sp The Bacterial Wilt Agent

In this study, we have aimed to determine the antagonistic effects of various rhizobacteria against representatives of bacterial wilt disease; Ralstonia pseudosolanacearum with a comparison from control sterile distilled water (SDW) aliquots. During in-vitro study, bacterial wilt agent was clearly inhibited in their growth by significant percentage by 32 different strains through perforated agar plate method. Results showed 10 potential strains among those 32 strains viz. DIB76/BCS-8, DIB76/BCS-9, DIB76/BCS-10, DIB76/BCS-12, DIB76/BCS-19, DIB76/BCS-20, DIB76/BCS-21, DIB76/BCS-24, DIB76/BCS-26 and DIB76/BCS-27 had the highest growth suppression for 9 different strains of R. pseudosolanacearum as compared to other bacterial strains. Trials with tomato crop at polyhouse had no incidence of bacterial wilt than those for control. Study, thus identifies 10 rhizobacterial strains from rhizosphere soil of diseased tomato plant possessing potential antagonistic activity against the wilt pathogen and has prospects as good biocontrol agents.

Larvicidal Effect of Vorticella microstoma (Ehrenberg, 1830) on Mosquito Larvae, and Morphological Changes under Induced Environmental Conditions.

Development of microbiota assemblage usually occurs in all most all domestic and peridomestic mosquito breeding habitats. There may be parasitic, epibiont, pathogenic, or even predatory species among this biota, and to investigate their potential against the mosquito population is worth studying. This may contribute to formulating environmentally agreeable approaches in controlling mosquitoes which is a current need. Vorticella spp. is a peritrich ciliate, and its trophont stage has become epibiont to certain biota. Further, their existence in seasonal water bodies that dry off during drought in tropical weather conditions is not known. Therefore, the potential of the larvicidal effect of Vorticella microstoma on different species of mosquito larvae was studied. We found that V. microstoma causes the 100% death of the third instar larvae of Culex tritaeniorhynchus (Giles, 1901) within 48 h of exposure. In contrast to that, this species did not cause any mortality to Aedes albopictus (Skuse, 1894) and Aedes aegypti (Linnaeus in Hasselquist, 1762) mosquito larvae in repeated trials. The dynamics of polymorphism of V. microstoma was studied under induced environmental conditions. V. microstoma remained as trophont stage throughout at room temperature (25 ± 2°C). When the temperature was reduced to 6°C, V. microstoma settled in the cyst stage. Evidently, V. microstoma is a good biocontrol agent of Culex species mosquito larvae, and they able to overcome drought periods in cyst forms. The findings of this study would be considered as the first step for a new avenue to work on environmentally agreeable manner in reducing the Culex spp. mosquito populations.

Characterization of bacteriophage VVP001 and its application for the inhibition of Vibrio vulnificus causing seafood-borne diseases

Vibrio vulnificus is a major food-borne pathogen that causes septicemia and cellulitis with a mortality rate of >50%. However, there are no efficient natural food preservatives or biocontrol agents to control V. vulnificus in seafood. In this study, we isolated and characterized a novel bacteriophage VVP001. Host range and transmission electron microscopy morphology observations revealed that VVP001 belongs to the family Siphoviridae and specifically infects V. vulnificus. Phage stability tests showed that VVP001 is stable at a broad temperature range of −20 °C to 65 °C and a pH range from 3 to 11, which are conditions for food applications (processing, distribution, and storage). In vitro challenge assays revealed that VVP001 inhibited V. vulnificus MO6-24/O (a clinical isolate) growth up to a 3.87 log reduction. In addition, complete genome analysis revealed that the 76 kb VVP001 contains 102 open reading frames with 49.64% G + C content and no gene encoding toxins or other virulence factors, which is essential for food applications. Application of VVP001 to fresh abalone samples contaminated with V. vulnificus demonstrated its ability to inhibit V. vulnificus growth, and an in vivo mouse survival test showed that VVP001 protects mice against high mortality (survival rate >70% at a multiplicity of infection of 1000 for up to 7 days). Therefore, the bacteriophage VVP001 can be used as a good natural food preservative and biocontrol agent for food applications.

Managing the Rugose Spiraling Whitefly Using Novel Technologies: Feasibilities and Possibilities

Rugose spiraling whitefly (RSW), Aleurodicus rugioperculatus Martin. is an invasive pest feeding on all the green leaved plants including oil palm causing nutrient as well as photosynthetic loss resulting in yield reductions. To manage the pest incidence, use of various possible and feasible measures in an integrated manner is the only available answer. Although many of these measures are not fool proof in giving 100 per cent control of the pest, in the present conditions it is the only solution to implement in the infested areas to reduce the pest incidence and infestation to below threshold limits. Based on the results obtained at different places, Good Agricultural Practices have been drawn for the successful mitigation of the pest. Most of these were tested in farmers’ fields and found suitable to implement in all the infested areas in an integrated manner rather than alone. The compatibility among different practices when implemented together shows the significance of individual as well as combined practices in managing the pest population. Since the pest is an invasive one with no boundaries on feeding, it is required to draw attention on Intergrated Pest Management (IPM) practices to check the population effectively. For this purpose all the possible measures like stopping procurement of nursery plants from the infested areas, taking control measures on all the feeding plants, growing pest repellent plants like marigold all around the garden, hanging sticky traps in the gardens to attract the adult flies and thereby reduce the pest load, conservation of existing and release of available parasitoids and predators need to be carried out in an integrated manner. Entomopathogen, Isaria fumosorosea fungus is a good and effective Myco biocontrol agent for causing maximum mortality of the pest population. The feasible practices on its multiplication using locally available low cost material were developed at ICAR-Indian Institute of Oil Palm Research, Pedavegi. The methodology to multiply the mother culture by farmers in their homes was also developed which is helpful for further multiplication and usage of it against the pest. The cost of multiplication of mother culture using locally available materials was found to be half the price to that of the laboratory prepared one. This methodology nullifies the farmers’ dependency for mother culture on various institutes/laboratories and helps to have sufficient culture with them. Keywords: Rugose spiraling whitefly, Isaria fumosorosea, Encarsia guadeloupae, oil palm.

Lesson from Ecotoxicity: Revisiting the Microbial Lipopeptides for the Management of Emerging Diseases for Crop Protection.

Microorganisms area treasure in terms of theproduction of various bioactive compounds which are being explored in different arenas of applied sciences. In agriculture, microbes and their bioactive compounds are being utilized in growth promotion and health promotion withnutrient fortification and its acquisition. Exhaustive explorations are unraveling the vast diversity of microbialcompounds with their potential usage in solving multiferous problems incrop production. Lipopeptides are one of such microbial compounds which havestrong antimicrobial properties against different plant pathogens. These compounds are reported to be produced by bacteria, cyanobacteria, fungi, and few other microorganisms; however, genus Bacillus alone produces a majority of diverse lipopeptides. Lipopeptides are low molecular weight compounds which havemultiple industrial roles apart from being usedas biosurfactants and antimicrobials. In plant protection, lipopeptides have wide prospects owing totheirpore-forming ability in pathogens, siderophore activity, biofilm inhibition, and dislodging activity, preventing colonization bypathogens, antiviral activity, etc. Microbes with lipopeptides that haveall these actions are good biocontrol agents. Exploring these antimicrobial compounds could widen the vistasof biological pest control for existing and emerging plant pathogens. The broader diversity and strong antimicrobial behavior of lipopeptides could be a boon for dealing withcomplex pathosystems and controlling diseases of greater economic importance. Understanding which and how these compounds modulate the synthesis and production of defense-related biomolecules in the plants is a key question—the answer of whichneeds in-depth investigation. The present reviewprovides a comprehensive picture of important lipopeptides produced by plant microbiome, their isolation, characterization, mechanisms of disease control, behavior against phytopathogens to understand different aspects of antagonism, and potential prospects for future explorations as antimicrobial agents. Understanding and exploring the antimicrobial lipopeptides from bacteria and fungi could also open upan entire new arena of biopesticides for effective control of devastating plant diseases.

Evaluation of enzyme production and biocontrol agent of zinc nanoparticles from Gonatorrhodiella parasitica

Background and objectives Biosynthesis of zinc nanoparticles (Zn NPs) is considered one of the new approaches for enzyme production and good biofertilizer and biocontrol agent for pathogenic disease of plant. The selected fungal strain Gonatorrhodiella parasitica was used for biosynthesis of Zn NPs. Determination of enzyme activity in fermentation medium containing olive mill wastes (OMW) as substrate for production of protease, pectinase, and chitinase at different pH values (6) was done to produce detailed information on the progress of reduction of zinc nitrate on the nanosecond times (6.0, 8.0, and 10.0). Absorbance ultraviolet–visible spectra of Zn NPs at pH 6.0 were at λmax 280 nm. Transmission electron spectroscopy measurements indicate that extracellular biosynthesis of Zn NPs by G. parasitica was in the size of 16 nm. Composting of OMW inoculated with G. parasitica for 15–30 days led to decrease in total phenol, flavonoids, 2,2 diphenyl-1-picrylhydrazyl (DPPH), and aflatoxins found in OMW. Comparison of G. parasitica free and nano zinc particles as biocontrol agent of soil-borne fungi causing preemergence and postemergence damping off of green bean plants (seed treatment) under field conditions measured from 7 to 60 days and its effect of growth parameters confirm the use of Zn NPs for enzymes production and biocontrol application. Materials and methods The local fungal strain G. parasitica used in this study was isolated from soil and identified at the Department of Chemistry of Natural and Microbial Products at the National Research Center. Determination of enzymes activity (pectinase, chitinase and protease) was done. Determination of major phytochemicals in prepared extracts (total phenolic content, total flavonoid content, DPPH scavenging activity, and aflatoxin) was done. A field experiment was conducted during the 2018 season at Kafer-Eldawar (Behira) Governorate, in a heavily naturally infested field, to study the effect of free and Zn NPs of G. parasitica on soil-borne fungi causing preemergence and postemergence damping off of green bean plants (seed treatment) under field conditions. Results and conclusion Composting of OMW inoculated with G. parasitica for 15–30 days led to decrease in total phenol, flavonoids, DPPH, and aflatoxins found in OMW. Moreover, suppressive soil-borne fungi caused preemergence and postemergence root rot of green bean plants (seed treatment) under field conditions.

Evaluation of Metarhizium anisopliae for rice planthopper control and its synergy with selected insecticides

Rice planthoppers are one of the most prominent pests of rice, and high resistance to insecticides has become a challenge for their control. In the present study, we investigated the effects of a new fungal strain M. anisopliae CQMa421 on two important rice planthoppers, Nilaparvata lugens (Stål) and Sogatella furcifera (Horváth) under both laboratory and field conditions. The synergy of M. anisopliae with insecticides (i.e., thiamethoxam, pymetrozine and buprofezin) on the two pests was also examined. The fungus M. anisopliae CQMa421 infected N. lugens and S. furcifera adults, with an LT50 of approximately 4 days observed under high conidial concentrations (1 × 108 conidia/ml). M. anisopliae also exhibited good compatibility with two selected insecticides, thiamethoxam and pymetrozine. The combined use of M. anisopliae with thiamethoxam or pymetrozine resulted in a shorter LT50 of approximately 1 day for N. lugens and S. furcifera than did the use of M. anisopliae alone. In the field trials, M. anisopliae effectively suppressed populations of rice planthoppers, and high control efficiency was observed with the combined application of M. anisopliae and thiamethoxam. Taken together, our results suggest that the fungus M. anisopliae CQMa421 is a good biocontrol agent for N. lugens and S. furcifera and that the combined use of M. anisopliae with insecticides is an alternative strategy for pest control.

Isolation and characterization of Aspergillus niger NBC001 underlying suppression against Heterodera glycines

Heterodera glycines is the most pervasive soybean pests worldwide. Biocontrol provides a strategy to sustainably control nematodes. In this study, 22 fungal isolates were obtained and identified from cysts of Heterodera spp. Among them, Aspergillus niger NBC001 showed high nematicidal activity against H. glycines. The 2-fold dilution of NBC001 culture filtrate caused 89% mortality of second-stage juveniles and inhibited more than 98% of egg hatching in vitro. In both pot and field experiments, the numbers of H. glycines cysts in soybean seedlings dressed with the the 5-fold concentrated culture filtrate of NBC001 were significantly reduced by 43% and 28%, respectively. In addition, application of NBC001 remarkably reduced the penetration of nematodes into the roots. Histochemical and fluorometric staining analyses indicate that application of NBC001 stimulated hydrogen peroxide activity in the roots and triggered callose deposition in the leaves and roots. Transcription of the PR1a and EREBP genes in the salicylic acid and ethylene signaling pathways was upregulated in soybean plants treated with NBC001. However, the application of concentrated culture filtrate of NBC001 had no significant impacts on the soil microbial community based on next generation DNA sequencing technology. In summary, NBC001 may be a good biocontrol agent against H. glycines via stimulation of the immunity/defense of the plant host.

Biocontrol traits of Bacillus licheniformis GL174, a culturable endophyte of Vitis vinifera cv. Glera

BackgroundBacillus licheniformis GL174 is a culturable endophytic strain isolated from Vitis vinifera cultivar Glera, the grapevine mainly cultivated for the Prosecco wine production. This strain was previously demonstrated to possess some specific plant growth promoting traits but its endophytic attitude and its role in biocontrol was only partially explored. In this study, the potential biocontrol action of the strain was investigated in vitro and in vivo and, by genome sequence analyses, putative functions involved in biocontrol and plant-bacteria interaction were assessed.ResultsFirstly, to confirm the endophytic behavior of the strain, its ability to colonize grapevine tissues was demonstrated and its biocontrol properties were analyzed. Antagonism test results showed that the strain could reduce and inhibit the mycelium growth of diverse plant pathogens in vitro and in vivo. The strain was demonstrated to produce different molecules of the lipopeptide class; moreover, its genome was sequenced, and analysis of the sequences revealed the presence of many protein-coding genes involved in the biocontrol process, such as transporters, plant-cell lytic enzymes, siderophores and other secondary metabolites.ConclusionsThis step-by-step analysis shows that Bacillus licheniformis GL174 may be a good biocontrol agent candidate, and describes some distinguished traits and possible key elements involved in this process. The use of this strain could potentially help grapevine plants to cope with pathogen attacks and reduce the amount of chemicals used in the vineyard.

Identification of a small antimycotic peptide produced by Bacillus amyloliquefaciens 6256

Bacillus sp. 6256 is a good biocontrol agent against Botrytis cinerea which caused tomato gray mold disease. Strain 6256 was identified as B. amyloliquefaciens by analysis of its partial gyrB gene sequence. To identify and characterize the antimycotic peptides from the culture broth of the bacterium, the antimicrobial substances produced by B. amyloliquefaciens 6256 were isolated by ammonium sulfate precipitation, Superdex 200 gel filtration chromatography and DEAE anion exchange chromatography. The purified compound was designated as P657. The biological activity of P657 was stable at as high as 100 °C for 20 min and in pH value ranged from 5 to 10. The antimycotic compound was resistant to trypsin and proteinase K, and could completely inhibit spore germination of Botrytis cinerea in vitro. MALDI-TOF-MS analysis results showed the presence of fengycins A (C16–C17) and fengycins B (C15–C17) isoforms in P657.

Identification and determination of characteristics of endophytes from rice plants and their role in biocontrol of bacterial blight caused by Xanthomonas oryzae pv. oryzae

Summary Endophytic bacteria of rice plants (Oryza sativa L.) from eight different cultivars were screened for their ability in inducing disease symptoms, plant growth promotion and antagonistic activity against Xanthomonas oryzae pv. oryzae. Out of the 63 whole isolates, five were plant pathogens. Based on phenotypic characteristics and 16S rDNA sequence analysis, these were identified as Pseudomonas oryzihabitans, P. fulva, Pantoea ananatis, Pantoea sp., Cellulomonas sp. Four out of the 63 isolates behaved as potentially good plant growth-promoting and biocontrol agents. These were identified as Bacillus sp., B. subtilis, Pseudomonas putida and Enterobacter sp. This is the first report of pathogenic and endophytic bacteria from rice grown in field conditions in North of Iran.

Desirable Traits of a Good Biocontrol Agent against Verticillium Wilt.

The soil-borne fungus Verticillium causes serious vascular disease in a wide variety of annual crops and woody perennials. Verticillium wilt is notoriously difficult to control by conventional methods, so there is great potential for biocontrol to manage this disease. In this study we aimed to review the research about Verticillium biocontrol to get a better understanding of characteristics that are desirable in a biocontrol agent (BCA) against Verticillium wilt. We only considered studies in which the BCAs were tested on plants. Most biocontrol studies were focused on plants of the Solanaceae, Malvaceae, and Brassicaceae and within these families eggplant, cotton, and oilseed rape were the most studied crops. The list of bacterial BCAs with potential against Verticillium was dominated by endophytic Bacillus and Pseudomonas isolates, while non-pathogenic xylem-colonizing Verticillium and Fusarium isolates topped the fungal list. Predominant modes of action involved in biocontrol were inhibition of primary inoculum germination, plant growth promotion, competition and induced resistance. Many BCAs showed in vitro antibiosis and mycoparasitism but these traits were not correlated with activity in vivo and there is no evidence that they play a role in planta. Good BCAs were obtained from soils suppressive to Verticillium wilt, disease suppressive composts, and healthy plants in infested fields. Desirable characteristics in a BCA against Verticillium are the ability to (1) affect the survival or germination of microsclerotia, (2) colonize the xylem and/or cortex and compete with the pathogen for nutrients and/or space, (3) induce resistance responses in the plant and/or (4) promote plant growth. Potential BCAs should be screened in conditions that resemble the field situation to increase the chance of successful use in practice. Furthermore, issues such as large scale production, formulation, preservation conditions, shelf life, and application methods should be considered early in the process of selecting BCAs against Verticillium.

A note on parasitisation of top borer by Isotima javensis Rohwer (Hymenoptera: Ichneumonidae)

Isotima javensis is a solitary ecto parasitoid of the sugarcane top borer, S. exceptalis. It attacks the prepupal stage and deposits an egg either on the prepupa or near its vicinity. The extent of parasitisation was observed 2.12%, 4.28%, 7.14%, 5.88% and 5.23 % in I, II, III, IV and V broods of top borer, respectively. The contribution of mortality of pupae of the top borer by parasitisation is high in III and IV broods (Aug-Oct), the time when the brood infestation remains generally very high. The maximum female ratio (59.72%) was observed in III brood of parasitisation followed by 55.20 % in IV brood. In I and II broods, however more or less equal number of males and females can be observed in the field. Equality in the sex ratio at this time ensures fertilisation of almost all the females for retaining the vigour and vitality of the species. The absence of unfertilized parasites naturally removes the chances of parthenogenetic reproduction and thus the number of females gradually rises in the succeeding season. It is concluded that there are several attributes of parasitoid i.e. specific parasite of top borer; its life cycle is much shorter than its host; active throughout the period of activity of the host and even it hibernates under north Indian conditions which make it a good biocontrol agent. It is suggested that parasitoid may be exploited in biological control programme, more detailed study is required for mass multiplication in the laboratory on an alternate host, release technique and survival in the sugarcane field.

Can toxicants used against cotton mealybug Phenacoccus solenopsis be compatible with an encyrtid parasitoid Aenasius bambawalei under laboratory conditions?

The cotton mealybug, Phenacoccus solenopsis Tinsley (Sternorrhyncha: Pseudococcidae) is a serious pest of various cultivated plants in Pakistan. Recent reports show that the parasitoid Aenasius bambawalei Hayat (Hymenoptera: Encyrtidae) is a good biocontrol agent of the pest. Compatibleness is important in any IPM programme, and the insecticide used must have little or no effects on the biological control agent. This study investigated the compatibility of neem treatments and a commercial insecticide, imidacloprid on A. bambawalei. Bioassays were laid out in a completely randomized design (CRD) under laboratory conditions. Results showed that the adult stage of the parasitoid was more susceptible to the commercial insecticide imidacloprid than the concealed pupal stage. Moreover, on the basis of the International Organization for Biological Control (IOBC) toxicity categories of the commercial insecticide, imidacloprid was moderately toxic throughout the study period (Ex >80%) while neem was slightly toxic after 24h of use (Ex <80%). Results also suggest that A. bambawalei release should be delayed for at least 1week after neem treatments. Because imidacloprid destroys A. bambawalei, it might cause resurgence of P. solenopsis; thus, farmers should avoid integrating the insecticide in the control of P. solenopsis.

Effective composting of empty fruit bunches using potential Trichoderma strains

Oil palm fibres are easy to degrade, eco-friendly in nature and once composted, they can be categorized under nutrient-enriched biocompost. Biocompost is not only a good biofertilizer but also a good biocontrol agent against soil-borne pathogens. In this research, experimental works on the composting of empty fruit bunches (EFB) from the oil palm industry were conducted using two potential Trichoderma strains. Analysis of pH initially found the soils to be slightly acidic. However, after composting, the soils were found to be alkaline. Trichoderma propagules increased by 72% in the soils compared to other fungi. Soil electrical conductivity was found to be 50.40μS/cm for compost A, 42.10μS/cm for compost B and 40.11μS/cm for the control. The highest C:N ratio was obtained for compost A at 3.33, followed by compost B at 2.79, and then the control at 1.55. The highest percentages of nitrogen (N), phosphorus (P), and potassium (K) were found in compost A (0.91:2.13:6.68), which was followed by compost B (0.46:0.83:5.85) and then the control (0.32:0.26:5.76). Thus, the biocomposting of oil palm fibres shows great potential for enhancing soil micronutrient, plant growth performance, and crop yield production.

The biocontrol efficacy and antibiotic activity of Streptomyces plicatus on the oomycete Phytophthora capsici

A Streptomyces plicatus isolate B4-7 was obtained from a citrus farm. B4-7 suppressed up to 75% mycelial growth of Phytophthora capsici, Phytophthora cinnamomi, Phytophthora palmivora and Phytophthora parasitica in the dual culture test on PSA plates. The hyperparasitism of B4-7 against P. capsici was confirmed under the scanning electron microscope. The chitin-potato sucrose broth, potato sucrose broth, rice bran broth and oatmeal broth cultural filtrates of B4-7 inhibited the mycelial growth and the zoospore germination of P. capsici in the in vitro tests. Abnormal formation of P. capsici zoospores were observed by light microscope after treating with B4-7 cultural filtrates for 24h. When the B4-7 cultural filtrates and P. capsici zoospore were inoculated simultaneously on bell pepper leaves, 100% disease suppression was observed. In the pot test, the B4-7 oatmeal (OM) cultural broth when added 3h post inoculation of P. capsici showed 75% crown rot disease reduction. The anti-fungal compound purified from B4-7 OM cultural broth was identified as borrelidin using spectral analysis. The results suggested that S. plicatus B4-7 could be a good biocontrol agent to be integrated in the Phytophthora blight management program.

Odonata Diversity at University of Southern Mindanao, Kabacan, Cotabato

Odonata are good biocontrol agents of agricultural pests and vector mosquitoes and even an indicator of environmental changes and health status of ecosystem. However, there are limited studies that have been conducted especially on lowland ecosystems. The study was conducted using time constraint with 4 exposure hours and opportunistic sampling protocols. Result of the study revealed 13 species of odonata belonging to three families, 2 of which are Zygopterans and only one family belonging to Anisoptera with 11 species. Libellulidae dominates the recorded species. 8 species are found in USMARC and 6 species in housing. One Philippine endemic was documented - Rhinocypha colorata . Diversity is low in the two sampling sites and high disturbance is found in housing (63%). Similarity index showed that 92% are disconcordant species. Low species diversity and low endemism of odonata is an indicator that the area is already disturbed as measured by the high number of common/oriental species and existence of environmental and anthropogenic activities. Thus, a conservation strategy for this important species will be implemented. Keywords: odonata, USM, disturbance, oriental species

Português

Biological control has been integrated into substances known as (Generally Regarded As Safe), these substances are commonly used as food additives, and its main role is to assist the biological agents antagonistic action. This study aimed to test the effects of five GRAS substances over the growth of four strains of yeast (5822, 5852, 5859, 5872) selected by presenting characteristics of good biocontrol agents. To perform the test, the strains were grown in GYMP broth with the addition of substances sodium bicarbonate, sodium carbonate, calcium carbonate, calcium chloride and potassium chloride at concentrations of 1%, 3% and 5% with the exception of chloride whose potassium concentrations were 0.1%, 0.5% and 1% (maximum concentration permitted by law). On days 1, 4, 7, and 10 after incubation an aliquot of 50 µl was removed and plated cultures, and the results expressed as CFU / ml. Among the four tested strains, only 5852 was able to survive seven days in the presence of sodium bicarbonate at the three concentrations tested. Demonstrating the ability of this yeast to be used in integrated biological control protocols with this substance.

Isolation and characterization of an antifungal protein from Bacillus licheniformis HS10

Bacillus licheniformis HS10 is a good biocontrol agent against Pseudoperonospora cubensis which caused cucumber downy disease. To identify and characterize the antifungal proteins produced by B.licheniformis HS10, the proteins from HS10 were isolated by using 30–60% ammonium sulfate precipitation, and purified with column chromatography on DEAE Sepharose Fast Flow, RESOURCE Q and Sephadex G-75. And the SDS–PAGE and MALDI-TOF/TOF-MS analysis results demonstrated that the antifungal protein was a monomer with molecular weight of about 55kDa, identified as carboxypeptidase. Our experiments also showed that the antifungal protein from B. licheniformis HS10 had significantly inhibition on eight different kinds of plant pathogenic fungi, and it was stable with good biological activity at as high as 100°C for 30min and in pH value ranged from 6 to 10. The biological activity was negatively affected by protease K and 10mM metal cations except Ca2+.

Trichoderma harzianum seed treatment controls Fusarium verticillioides colonization and fumonisin contamination in maize under field conditions

In northern Italy, the most frequently occurring class of mycotoxins in maize are fumonisins, mainly those produced by Fusarium verticillioides. Currently, good agricultural practices (GAPs) represent the best line of defense for controlling the contamination of maize by Fusarium-toxins. Annual fluctuations in weather conditions can strongly reduce the advantages conferred by GAPs, and thus integration with biological control strategies can be a sustainable way to achieve reliable control of Fusarium colonization and toxin contamination. Trichoderma harzianum is a good biocontrol agent against a wide range of plant pathogens, and previous studies have reported its ability to reduce F. verticillioides colonization under greenhouse conditions. Field trials were conducted in two locations to assess the effect of seed treatment with T. harzianum strain T22 on F. verticillioides kernel colonization and on fumonisin contamination under various natural conditions. An average reduction of 58% in fungal infestation and 53% in mycotoxin contamination was observed during our three-year experiments. This research suggests that seed biopriming with T. harzianum T22 can be a promising and environmentally friendly way to control F. verticillioides kernel colonization and fumonisin accumulation.