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Antifungal lactic acid bacteria with potential to prolong shelf-life of fresh vegetables

Sathe, S.J., Nawani, N.N., Dhakephalkar, P.K., Kapadnis, B.P.
Journal of applied microbiology 2007 v.103 no.6 pp. 2622-2628
Aspergillus flavus, Botrytis cinerea, Fusarium graminearum, Magnaporthe salvinii, Rhizopus stolonifer, Sclerotinia minor, Thanatephorus cucumeris, Weissella, agar, antifungal properties, conidia, food spoilage, fungi, lactic acid bacteria, raw vegetables, ribosomal RNA, sequence analysis, shelf life, spoilage, vegetables
The aim of this study was to isolate and identify antifungal lactic acid bacteria from fresh vegetables, and evaluate their potential in preventing fungal spoilage of vegetables. Lactic acid bacteria from fresh vegetables were enriched in MRS (de Man Rogosa Sharpe) broth and isolated by plating on MRS agar. All the isolates (359) were screened for activity against Aspergillus flavus of which 10% showed antifungal activity. Potent antifungal isolates were identified by phenotypic characters and confirmed by partial 16S rRNA gene sequencing. These were screened against additional spoilage fungi viz. Fusarium graminearum, Rhizopus stolonifer, Sclerotium oryzae, Rhizoctonia solani, Botrytis cinerea and Sclerotinia minor by overlay method. Most of the isolates inhibited wide range of spoilage fungi. When fresh vegetables were inoculated with either cell suspension (10⁴ cells ml⁻¹) or cell-free supernatant of Lact. plantarum, followed by application of vegetable spoilage fungi (A. flavus and F. graminearum, R. stolonifer, B. cinerea each with 10⁴ conidia ml⁻¹) the vegetable spoilage was significantly delayed than control. Fresh vegetables constitute a good source of lactic acid bacteria with ability to inhibit wide range of spoilage fungi. Such bacteria can be applied to enhance shelf-life of vegetables. In the present study, we report for the first time the antifungal activity of Weissella paramessenteroides and Lact. paracollinoides isolated from fresh vegetables, against wide range of food spoilage fungi. Fresh vegetables can be used as a source of antifungal lactic acid bacteria. Their exploitation as biopreservative will help in prolonging shelf-life of fresh vegetables.