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Producing cell‐free culture broth of rhamnolipids as a cost‐effective fungicide against plant pathogens
Author(s) -
Sha Ruyi,
Jiang Lifang,
Meng Qin,
Zhang Guoliang,
Song Zhirong
Publication year - 2012
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.201100295
Subject(s) - rhamnolipid , fungicide , microbiology and biotechnology , biology , food science , pseudomonas aeruginosa , chemistry , bacteria , botany , genetics
Biosurfactants of rhamnolipids have been enthusiastically investigated for substitutes of synthetic agrochemicals against plant pathogens. However, all such studies have been conducted on rhamnolipids with high purity which have limitations due to high costs. This paper focused on the applicability of rhamnolipid‐containing cell‐free culture broth. It was found that rhamnolipids in cell‐free culture broth of Pseudomonas aeruginosa ZJU211 were largely composed of di‐rhamnolipid and mono‐rhamnolipid with the ratio varying with culture time. After 96 h of fermentation, the mass ratio of di‐rhamnolipid over mono‐rhamnolipid increased to 2.6:1. Crude rhamnolipids in a form of cell‐free culture broth showed high antifungal activity against colony growth and biomass accumulation of seven plant pathogens comprising two Oomycetes , three Ascomycota and two Mucor spp. fungi, among which three plant pathogens were firstly reported in this paper showing inhibition to rhamnolipids. Particularly, rhamnolipids showed potent activity against two Oomycetes that acquire resistance to commercial compound of metalaxyal. Furthermore, di‐rhamnolipid was elucidated to dominate the antifungal activity of crude rhamnolipids by in vitro studies. At last, the efficacy and safety of cell‐free culture broth was preliminarily illustrated on plants in vivo . So cell‐free culture broth as a crude rhamnolipid product could be served as a potential cost‐effective and environmental‐friendly fungicide in agriculture. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)