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Effects of temperature, pH, water activity and CO 2 concentration on growth of Rhizopus oligosporus NRRL 2710
Author(s) -
Sparringa R.A.,
Kendall M.,
Westby A.,
Owens J.D.
Publication year - 2002
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1046/j.1365-2672.2002.01534.x
Subject(s) - rhizopus oligosporus , hypha , fermentation , mycelium , food science , water activity , chemistry , growth rate , botany , biology , water content , geotechnical engineering , engineering , geometry , mathematics
Aims: To investigate the effects of temperature, pH, water activity ( a w ) and CO 2 concentration on the growth of Rhizopus oligosporus NRRL 2710. Methods and Results: Hyphal extension rates from mycelial and spore inocula were measured on media with different a w (˜ 1·0, 0·98 and 0·96) and pH (3·5, 5·5 and 7·5) incubated at 30, 37 or 42°C in atmospheres containing 0·03, 12·5 or 25% (v/v) CO 2 . The effects of environmental conditions on hyphal extension rate were modelled using surface response methodology. The rate of hyphal extension was very sensitive to pH, exhibiting a pronounced optimum at pH 5·5–5·8. The hyphal extension rate was less sensitive to temperature, a w or CO 2 , exhibiting maximum rates at 42°C, a w ˜ 1·0 and 0·03% (v/v) CO 2 . Conclusions: The fastest hyphal extension rate (1·7 mm h −1 ) was predicted to occur at 42°C, pH 5·85, a w ˜ 1·0 and 0·03% CO 2 . Significance and Impact of the Study: The present work is the first to model the simultaneous effects of temperature, pH, a w and CO 2 concentration on mould growth. The information relates to tempe fermentation and to possible control of the microflora in Tanzanian cassava heap fermentations.