一株油脂降解菌的分离筛选及固定化

Screening and immobilization of a strain capable of degrading oil

摘要:

【背景】高效菌株是影响生物法降解油脂污染物效率的关键因素之一。【目的】筛选高效的油脂降解菌，对其固定化条件进行优化，并评估固定化菌降解油脂效率。【方法】通过油脂降解平板筛选，从萍乡传统腊肉中分离到一株降解油脂能力较强的菌株；以16S rRNA基因鉴定了其分类地位，并采用3项致病性指标检测了其安全性。通过单因素试验和正交试验优化了固定化条件，对比了固定化菌和游离菌对大豆油油脂的降解效果，评估了固定化菌的重复使用效果及对实际污水中油脂的降解效果。【结果】筛选菌株为葡萄球菌(Staphylococcus sp.)，无致病性。最佳固定化条件为：海藻酸钠浓度4.0%，CaCl₂浓度2.0%，海藻酸钠溶液与菌液的体积比为1:1，交联时间8.0 h。固定化菌在pH 7.0、30.0 ℃、180.0 r/min培养3.0 d的情况下，对大豆油的油脂降解率最高可达65.7%，比游离菌高14.1%，比游离菌具有更宽的pH适应范围和更强的冷热稳定性，重复使用4次仍具有较好的油脂降解效果。【结论】固定化菌对食堂下水道污水油脂的降解率达到了41.6%，该固定化菌球对大豆油和实际污水都具有一定的油脂降解效果。

关键词:传统腊肉;油脂降解菌;分离筛选;固定化

Abstract:

[Background] Efficient strains are the key to the biodegradation of oil pollutants. [Objective] To screen an efficient oil-degrading strain, optimize its immobilization conditions, and evaluate the oil degradation efficiency of the immobilized strain. [Methods] A highly efficient oil-degrading strain was isolated from traditional bacon in Pingxiang by the plate culture method and identified by 16S rRNA gene sequencing. The safety of the strain was evaluated based on three pathogenic indicators. The immobilization conditions of the strain were optimized by single factor tests and an orthogonal design. The degradation effects of the immobilized strain and free strain on soybean oil were compared. Furthermore, the reuse effect and the degradation effect of the immobilized strain on the oil in sewage were evaluated. [Results] The strain was identified as Staphylococcus sp., and it was not pathogenic. The optimal immobilization conditions for the strain were 4.0% sodium alginate, 2.0% CaCl₂, sodium alginate solution:strain suspension volume ratio of 1:1, and crosslinking for 8 h. In the case of degrading soybean oil at pH 7.0, 30.0 ℃, and 180.0 r/min for 3 days, the immobilized strain achieved the highest degradation rate of 65.7%, which was 14.1% higher than that of the free strain. Moreover, the immobilized strain had tolerance to a wider pH range and stronger thermal stability than the free strain, and it demonstrated high oil-degrading ability after being repeatedly used for 4 times. [Conclusion] The degradation rate of the immobilized strain reached 41.6% for the oil in sewage. The immobilized strain can degrade both soybean oil and sewage oil, demonstrating a broad application prospect.

Key words:traditional bacon;oil-degrading strain;screening;immobilization