氯嘧磺隆高效降解真菌F8的分离和鉴定

从田间多年施用氯嘧磺隆的土壤中,驯化分离得到一株能够以氯嘧磺隆为唯一碳源和能源生长的真菌F8,F8在麦芽汁液体培养基中发酵96h,对10mgL-1氯嘧磺隆的降解率为93.07%。F8明显促进土壤中氯嘧磺隆的降解,20μgkg-1氯嘧磺隆的降解半衰期由对照的46.52d缩短为15.03d。F8在麦芽汁平板培养基上形成的菌落为乳白色,圆形,干燥,绒毛状或粉状,中心突起;经电镜观察,细胞长宽比大于2,形成发达的假菌丝,连接成树枝状;糖类发酵试验表明:F8能发酵葡萄糖、蔗糖、麦芽糖、半乳糖,不能发酵淀粉、乳糖;同化碳源试验表明:F8能利用葡萄糖、蔗糖、麦芽糖,不能利用淀粉、乙酸钠;同化氮源试验表明:F8不能利用硝酸钾,能利用硫酸铵,尿素;能分解脂肪,能胨化牛奶,不能液化明胶,不能同化乙醇,不能产生淀粉化合物,不能产酸,不能产酯。根据其形态特征,生理生化特性、18SrRNA序列分析,初步鉴定F8为酿酒酵母(Saccharomyces cerevisiae)。

Isolation and Identification of a Fungi Strain F8 Capable of Degrading Chlorimuron-ethyl

Chlorimuron-ethyl is used widely all over the world for the control of broadleaf weeds in the soybean field. However chlorimuron-ethyl is not prone to degrade and carryover injury problem is very serious. Bioremediation is an effective and economic method to treat the soil that has been polluted by pesticides.To search for microorganisms that can degrade chlorimuron-ethyl with high efficiency, a fungi strain, coded as F8 which could utilize chlorimuron-ethyl as sole carbon and energy source for growth,was isolated and screened from the soil applied with chlorimuron-ethyl for longterm. The strain's degrading rate on chlorimuron-ethyl of 10mg L-1 in Mayazhi liquid medium for 96 h was 93.07 %. Introduction of F8 into soil was effective in promoting chlorimuron-ethyl degration too,and degradation half-life was shortened from 46.52d to 15.03d.The fungi colonies on Mayazhi plate appeared circular and milk white in color,dry,villiform or floury, and center protuberated. Length to width ratio of F8 cell is >2, forming pseudohyphal,link as arborization.The saccharide fermentation tests showed that the strain could ferment glucose, sucrose, maltose and galactose, but could not ferment amylum and lactose. The carbon source assimilation tests showed that the strain could utilize glucose, sucrose and maltose, but could not utilize amylum and sodium acetate. The nitrogen source assimilation tests showed that the strain could not utilize potassium nitrate, but could utilize ammonium sulphate and urea. Laboratory tests also showed that the strain could decompose fat, and could peptonize milk,but could not liquefy gelatin,could not assimilate ethanol,coulod not produce amylum compound,and coulod not produce acid and ester. Based on its morphological, physiological and biochemical properties as well as the 18S rRNA sequence analysis result, the strain was tentatively identified as Saccharomyces cerevisiae.