Cairns-Fuller V, Aldred D, Magan N
Applied Mycology Group, Institute of BioScience and Technology, Cranfield University, Silsoe, Bedford, UK.
J Appl Microbiol. 2005;99(5):1215-21. doi: 10.1111/j.1365-2672.2005.02695.x.
To examine the effect of interactions between water, temperature and gas composition on growth and ochratoxin A (OTA) production by isolates of Penicillium verrucosum in vitro and in situ on grain-based media and wheat grain.
Three isolates of P. verrucosum were examined in relation to radial growth rate and OTA production, and to interacting conditions of water activity (a(w)), temperature and gas composition on a milled wheat medium. Subsequently, detailed temporal studies were carried out on gamma irradiated wheat grain over the range 0.75-0.995 a(w), 10-25 degrees C and air, 25 or 50% CO(2). This showed that optimum growth of P. verrucosum was at 0.98 a(w) in vitro at 25 degrees C, but at 0.95 a(w) and 25 degrees C on wheat grain. The a(w) minimum for growth was about 0.80 a(w), although no OTA was produced under this condition even after 56 days. Significant inhibition of growth and OTA production occurred with 50% CO(2), and 0.90-0.995 a(w) at 25 degrees C.
The optimum and marginal conditions for growth and OTA production on wheat grain have been identified. At least 50% CO(2) is needed to inhibit growth and OTA production by >75% in moist grain (0.90-0.995 a(w)).
First detailed identification of optimal and marginal interacting conditions of water/temperature and gas composition on growth and OTA production by P. verrucosum on wheat grain. This is a critical component of the postharvest management strategy for minimizing contamination by this important mycotoxin and predicting risk, based on environmental conditions, during drying and storage.
研究水分、温度和气体成分之间的相互作用对疣孢青霉分离株在体外以及在基于谷物的培养基和小麦籽粒上原位生长及赭曲霉毒素A（OTA）产生的影响。
研究了三株疣孢青霉在磨碎的小麦培养基上的径向生长速率和OTA产生情况，以及水分活度（a(w)）、温度和气体成分之间的相互作用条件。随后，对经γ射线辐照的小麦籽粒在0.75 - 0.995 a(w)、10 - 25℃以及空气、25%或50% CO₂条件下进行了详细的时间研究。结果表明，疣孢青霉在体外25℃时a(w)为0.98时生长最佳，但在小麦籽粒上a(w)为0.95且温度为25℃时生长最佳。生长的最低a(w)约为0.80，尽管在此条件下即使经过56天也未产生OTA。在25℃时，50% CO₂以及a(w)为0.90 - 0.995时，生长和OTA产生受到显著抑制。
已确定小麦籽粒上生长和OTA产生的最佳及临界条件。在潮湿谷物（0.90 - 0.995 a(w)）中，至少需要50% CO₂才能使生长和OTA产生受到>75%的抑制。
首次详细确定了水分/温度和气体成分对疣孢青霉在小麦籽粒上生长和OTA产生的最佳及临界相互作用条件。这是收获后管理策略的关键组成部分，可基于环境条件在干燥和储存期间将这种重要霉菌毒素的污染降至最低并预测风险。
