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Effect of water activity and temperature on germination and growth of Penicillium digitatum , P. italicum and Geotrichum candidum
Author(s) -
Plaza P.,
Usall J.,
Teixidó N.,
Viñas I.
Publication year - 2003
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.1365-2672.2003.01909.x
Subject(s) - penicillium digitatum , geotrichum , penicillium italicum , germination , food spoilage , water activity , biology , mycelium , spore germination , conidium , botany , penicillium , postharvest , horticulture , water content , genetics , geotechnical engineering , bacteria , engineering
Aims: This study compares the effect of temperature (4–37°C) and water activity ( a w : 0·99–0·87) and their interactions on the germination rates, lag times prior to germination and mycelial growth ‘in vitro’ of Penicillium digitatum , P. italicum and Geotrichum candidum , the main postharvest pathogens affecting citrus fruits. Methods and Results: Germination and growth were markedly influenced by temperature and a w . Generally, lag times were longer and germination and growth rates were slower when conditions of temperature and a w were far from optimum. All the studied species were able to germinate over a range of 4–30°C at 0·995 a w , although in non‐optimal conditions P. digitatum only reached 40–60% of germinated conidia. At low temperatures, P. italicum germinated and grew faster than P. digitatum and G. candidum , particularly at 0·95 a w . Penicillium italicum was also able to germinate and grow in the driest studied conditions (0·87 a w ), while G. candidum did not germinate under 0·95 a w . Conclusions: Knowledge of the ecological requirements of these fungi is important in order to understand their behaviour in natural situations and to predict fungal spoilage on citrus fruits.