弯曲乳酸杆菌HB02抑制黄曲霉生长及产毒

Inhibition of growth and aflatoxin production of Aspergillus flavus by Lactobacillus curvatus HB02

用厌氧培养法对1株具霉菌抑制活性的弯曲乳酸杆菌(HB02)进行了培养,用气相色谱和比色法测定了培养物中挥发性脂肪酸(VFA)及乳酸的含量,并通过共培养法检测了该菌对黄曲霉生长和产毒的抑制效果。试验结果显示:该菌在双层固体培养基上生长缓慢,而在改良MRS液体培养基中生长较快。37℃培养48 h后培养液中乙酸51.75mmol.L-1、丙酸0.77 mmol.L-1、丁酸0.37 mmol.L-1、乳酸28.06 mmol.L-1。乳酸试验表明,培养基中添加的乳酸越多,培养基pH值越低,黄曲霉菌丝产量越低,而黄曲霉毒素B1的产量则有增加的趋势,表明乳酸所致低pH值只能抑制黄曲霉生长而不能抑制其产毒。当HB02与黄曲霉共培养时,黄曲霉菌丝产量和黄曲霉毒素B1产量均比黄曲霉单独培养时低(P<0.01)。结论:HB02可显著抑制黄曲霉生长及黄曲霉毒素B1的产生。

Lactobacillus curvatus HB02, which could inhibit growth of fungi, was cultured on doubled-layered agar or in liquid anaerobic cultivation medium. The content of volatile fatty acid （VFA） or lactic acid in cultural medium was measured by gas chromatography or colorimeter. The inhibition of HB02 on growth and toxin generation of Aspergillus flavus was determined by co-culture of HB02 with the fungi. The results showed that HB02 grew faster in MRS liquid medium than in solid plate. And in the cultural medium, the content of acetic acid, propionic acid, butyric acid and lactic acid was 51.75 mmol·L^-1 , 0.77 mmol·L^-1, 0. 37 mmol·L^-1, and 28.06 mmol·L^-1, respectively. The further experiment showed that the more lactic acid was added in the medium, the lower the pH of medium was, and the lighter the mycelium was. While the production of aflatoxin B1 increased with the decrease of pH, which implied that the low pH resulted from lactic acid in medium inhibited the growth of Aspergillus flavus but not the production of aflatoxin B1. While the HB02 strain was co-cultured with Aspergillus flavus, the weight of the mycelium and the production of aflatoxin B1 were both significantly lower than those of Aspergillus flavus cultured without HB02. The results implied that the mechanism of the inhibition on the growth of fungi and the production of toxin by HB02 strain resulted from many factors involving the low pH of medium, other metabolized production and interact between microorganism.