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Effects of culture conditions on spore types of C lonostachys rosea 67‐1 in submerged fermentation
Author(s) -
Sun M.H.,
Chen Y.M.,
Liu J.F.,
Li S.D.,
Ma G.Z.
Publication year - 2014
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/lam.12193
Subject(s) - chlamydospore , spore , fermentation , conidium , biology , biological pest control , inoculation , botany , horticulture , food science , microbiology and biotechnology
Abstract The promising biocontrol isolate C lonostachys rosea 67‐1 was investigated to clarify the effects of culture conditions on chlamydospore production in submerged fermentation. Culture conditions significantly affected both performance and types of C . rosea sporulation. C . rosea 67‐1 was hard to generate chlamydospores under conventional conditions. However, the proportion of resistant spores increased to 17·4 and 15·5% in PD and rice meal media, respectively, in 8 days. Chlamydospore productivity was boosted (>threefold) with the addition of 50–200 mg l −1 CuSO 4 . The pH of the medium played a vital role in 67‐1 sporulation. The percentage of chlamydospores decreased rapidly with increased p H (88·1% at p H 3·0 to 1·0% at pH 6·5). The optimal p H for conidia production was 6·0–6·5, at which chlamydospore forming was strongly inhibited. Regulating p H during fermentation contributed to improving output and proportion of resistant spores. When 67‐1 was inoculated into broth with an initial p H of 6·5, followed by adjustment to pH 3·5 after 48 h, the number of chlamydospores reached 1·1 × 10 8 ml −1 . The impact of temperature and rotational speed was also analysed; an ultimate capacity of chlamydospores was achieved at 30°C and the speed above 120 rev min −1 ( P < 0·05). Significance and Impact of the Study Clonostachys rosea is one of the most promising biocontrol agents in countering many plant fungal diseases. However, large‐scale production and commercialization are hampered by the lack of understanding of the impacts of culture conditions on performance and types of C. rosea sporulation and subsequently inadequate research on the techniques for chlamydospore production. In addressing these concerns, this study provides a unique insight into the manipulation of C. rosea sporulation and chlamydospore fermentation of the biocontrol fungus.