产几丁质酶菌株的筛选、鉴定及其对玉米秸秆中优势霉菌的抑制作用

Screening and Identification of Chitinase Producing Strain and Its Inhibition Action to Dominant Moulds in Corn Stalk

本试验旨在研究利用产几丁质酶菌株抑制玉米秸秆中优势霉菌的生长,为提高秸秆利用率提供理论依据。利用胶体几丁质培养基从玉米秸秆样品中筛选出一株产几丁质酶菌株BS-1,同时将优势霉菌进行分离、纯化。通过对BS-1菌株和优势霉菌形态学观察以及16 S r DNA或18 S r DNA序列测定进行菌种鉴定。利用3,5-二硝基水杨酸比色法测定BS-1菌株发酵24、48、72、96、120、144、168 h的几丁质酶活性,以及牛津杯法检测BS-1菌株发酵液对玉米秸秆中优势霉菌的抑制作用。结果显示,玉米秸秆样品中分离出的BS-1菌株经鉴定为枯草芽孢杆菌(Bacillus subtilis),4株优势霉菌分别为卷枝毛霉(Mucor circinelloides)、尖孢镰刀菌(Fusarium oxysporum)、米曲霉(Aspergillus oryzae)和黑曲霉(Aspergillus niger)。BS-1菌株在37℃下培养120 h产几丁质酶活性达到最高值3.23 U/m L。BS-1菌株发酵液对玉米秸秆中4株优势霉菌均有明显抑制作用,抑菌圈直径分别为18.13、18.48、17.55、15.68 mm。由此可见,筛选到的产几丁质酶枯草芽孢杆菌BS-1能够有效抑制玉米秸秆中的卷枝毛霉、尖孢镰刀菌、米曲霉、黑曲霉4株优势霉菌生长。

The objective of this experiment was to inhibit the growth of dominant moulds in corn stalk using chitinase producing strain, and provide a reference for improving the utilization efficiency of corn stalk. Chiti- nase producing strain of BS-1 was screened from corn stalk using colloidal chitin medium. At the same time, the dominant moulds were isolated and purified. Identification of strain BS-1 and dominant moulds were carried out through morphological observation and 16S rDNA or 18S rDNA sequence analysis. In addition, the chiti- nase activity of strain BS-1 was assayed using 3,5-dinitrosalicylic acid colorimetric method after 24, 48, 72, 96, 120, 144 and 168 h of fermentation and the inhibition action of fermentation liquid of strain BS-1 to domi- nant moulds was detected by oxford cup method. The results showed as follows： strain BS-1 isolated from corn stalk was Bacillus subtilis and four dominant moulds were Mucor circinelloides, Fusarium oxysporum, Asper- gillus oryzae and Aspergillus niger, respectively. After 120 h of fermentation at 37 ~C, the highest chitinase ac- tivity of strain BS-1 was obtained to be 3.23 U/mL. The fermentation liquid of strain BS-1 showed obvious in- hibition to four dominant moulds from corn stalk, the diameter of inhibition zone was 18.13, 18.48, 17.55 and 15.68 mm, respectively. In conclusion, the screened chitinase producing Bacillus subtilis BS-1 can effectively inhibit the growth of dominant moulds of Mucor circinelloides, Fusarium oxysporum, Aspergillus oryzae and Aspergillus niger from corn straw.