Production of β-1,3-glucanase and chitinase of two biocontrol agents and their possible modes of action
ABSTRACT Pichia membranefaciens Hansen and Candida guilliermondii (Cast) Langeronet Guerra are two antagonists of R. stolonifer on harvested nectarine and peach fruits. In this study, β-1,3-glucanase and chitinase activities of the antagonists were
induced in vitro and in vivo. The highest β-1, 3-glucanase activity was detected in Lilly-Barnett minimal salt medium supplemented with glucose in combination
with CWP of R. stolonifer as a carbon source. The β-1,3-glucanase activity of P. membranefaciens reached the maximum level, being 114.0 SU (specific activity unit), and that of C. guilliermondii reached 103.2 SU. The lowest β-1,3-glucanase activity was observed in the medium containing glucose as sole carbon source.
P. membranefaciens was able to produce significantly higher levels of chitinase (exochitinase and endochitinase) in vitro than C. guilliermondii grown in Czapeck minimal medium. An increase in β-1,3-glucanase and chitinase activity was also triggered by wounding, adding
of carbon sources and yeast cells. The results showed that both β-1,3-glucanase and chitinase from P. membranefaciens and C. guilliermondii exhibited some effects on controlling R. stolonifer, and might have a synergistic activity against R. stolonifer.
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ABSTRACT: The aim of this study was to determine the putative modes of action of 59 viticultural yeasts (31 Saccharomyces and 28 non-Saccharomyces) that inhibited fungi isolated from sour and grey rot in grapes. Inhibition of fungal mycelial growth by metabolites, enzyme activities (laminarinases, chitinases), antifungal volatiles, competition for nutrients (siderophores, Niche Overlap Index (NOI)), inhibition of fungal spore germination and decreased germinal tube length and induction of resistance were assayed. Biofungicide yeasts were classified into "antifungal patterns", according to their mechanisms of action. Thirty isolates presented at least two of the mechanisms assayed. We propose that inhibition of fungal mycelial growth by metabolites, laminarinases, competition for nutrients, inhibition of fungal spore germination and decreased germinal tube length, and antifungal volatiles by Saccharomyces and non-Saccharomyces viticultural yeasts is used as putative biocontrol mechanisms against phytopathogenic fungi. Twenty-four different antifungal patterns were identified. Siderophore production (N)and a combination of siderophore production and NOI>0.92 (M)were the most frequent antifungal patterns observed in the biofungicide yeasts assayed. Elucidation of these mechanisms could be useful for optimization of an inoculum formulation, resulting in a more consistent control of grey and sour rot with Saccharomyces and non-Saccharomyces biocontrol yeasts. Copyright © 2015 Elsevier B.V. All rights reserved.International journal of food microbiology 03/2015; 204:91-100. DOI:10.1016/j.ijfoodmicro.2015.03.024 · 3.16 Impact Factor
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ABSTRACT: The nematicidal effect of Pseudomonas fluorescens, Paecilomyces lilacinus, Pichia guilliermondii and Calothrix parietina singly or in combination was tested against root-knot nematode, Meloidogyne incognita. Treatments with P. fluorescens and P. lilacinus caused mortality of M. incognita as 45% and 30% of juveniles after 48 h of exposures, respectively compared to water control in vitro. Under greenhouse conditions, all treatments reduced the disease severity and enhanced plant growth compared to untreated control. Application of P. fluorescens, P. lilacinus and P. guilliermondii Moh 10 was more effective compared to C parietina. There was a negative interaction between C. parietina and either P. lilacinus or P. guilliermondii. Fresh and dry weight of shoots and roots of plants were significantly reduced as a result of infection with M. incognita, however application of biocontrol agents singly or in mix recovered this reduction. Moreover, they enhanced the growth parameters compared with the control. Our results proved that application of different biocontrol agents (P fluorescens, P. lilacinus and P guilliermondii) not only has a lethal effect on nematode, but also enhances the plant growth, supplying many nutritional elements and induction the systemic resistance in plants. Presence of C. parietina as a soil inhabitant cyanobacterium could antagonize biocontrol agents leading to the reduction of their practical efficiency in soil. (c) 2010 Elsevier Ltd. All rights reserved.Crop Protection 03/2011; 30(3):285-292. DOI:10.1016/j.cropro.2010.12.009 · 1.54 Impact Factor
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ABSTRACT: Postharvest diseases cause considerable losses to harvested fruits, vegetables, roots, and tubers during transportation from farmers’ field to market and in storage. Synthetic fungicides are the primary means to control postharvest diseases. However, microbial control has emerged as one of the most promising alternatives to chemical fungicides. Several microbial agents have been widely investigated for use on different postharvest pathogens. The efficacy of the microbial antagonist(s) can be enhanced if they are used with low doses of fungicides, salt additives, and plant products. At the international level, different microbial antagonists such as Candida sake, Candida oleophila, Cryptococcus laurentii, and Debaryomyces hansenii are being used. Biocontrol products such as Aspire, BioSave, and Shemer have also been developed and registered. Although the results of this technology are encouraging, the formulation and application methods are key issues for the efficacy and successful outcome of the commercial product.Bioaugmentation, Biostimulation and Biocontrol, Edited by Ajay Singh, Nagina Parmar, Ramesh C. Kuhad, 01/2011: chapter 13: pages 311-355; Springer Berlin Heidelberg., ISBN: 1613-3382