一株产油脂降解酶与生物表面活性剂的嗜麦芽寡养单胞菌的筛选及其特性

Isolation and characterization of a lipase- and biosurfactant-producing strain of Stenotrophomonas maltophilia

摘要:

餐厨垃圾中含有难降解油脂，易发生酸败，进而造成环境污染。目的 从餐厨垃圾中筛选高效产脂肪酶菌株，优化其产酶条件，并评价其胞外产物在餐厨垃圾中的油脂降解潜力。方法 采用中性红培养基从食堂泔水中分离筛选产脂肪酶菌株，并结合形态学特征及16S rRNA基因序列进行鉴定；通过单因素试验和响应面法优化脂肪酶产酶条件；分析脂肪酶性质及胞外聚合物(extracellular polymeric substances, EPS)的乳化性能。结果 从泔水样品中获得1株产脂肪酶能力强且具有生物表面活性的菌株C24202，鉴定为嗜麦芽寡养单胞菌(Stenotrophomonas maltophilia)。响应面优化结果显示，其最佳发酵条件为：乳糖10.0 g/L、酵母膏7.5 g/L、乳化大豆油40.0 g/L、FeSO₄ 8.0 g/L、温度34 ℃、初始pH 6.5、培养72 h，此时脂肪酶活力达(229.64±2.17) U/mL，为优化前的2.55倍。该脂肪酶最适温度为60 ℃，在50 ℃下孵育6 h仍保留50.70%的活性。菌株产生的EPS具有良好的乳化性能，其EI₂₄值为46.92%，红外光谱分析表明其可能为聚合型糖脂肽类生物表面活性剂。结论 该菌株兼具产耐热脂肪酶和生物表面活性剂的能力，在油脂降解及含油废水处理领域具有良好的应用前景。

Abstract:

Kitchen waste contains recalcitrant lipids that are prone to rancidification and can cause environmental pollution.Objective To isolate efficient lipase-producing strains from kitchen waste, optimize their enzyme production conditions, and evaluate the lipid-degrading potential of their extracellular products in kitchen waste.Methods Lipase-producing strains were isolated from canteen swill via the neutral red medium and identified based on morphological characteristics and 16S rRNA gene sequences. Lipase production conditions were optimized through single-factor experiments and response surface methodology. The properties of the lipase and the emulsification performance of extracellular polymeric substances (EPS) were analyzed.Results A strain designated C24202, exhibiting strong lipase- and biosurfactant-producing activity, was isolated and identified as Stenotrophomonas maltophilia. The fermentation conditions were optimized as follows: lactose 10.0 g/L, yeast extract 7.5 g/L, emulsified soybean oil 40.0 g/L, FeSO₄ 8.0 g/L, and incubation at 34 ℃ and initial pH 6.5 for 72 h. Under these conditions, the lipase activity reached (229.64±2.17) U/mL, representing a 2.55-fold increase compared with the pre-optimization level. The lipase exhibited an optimal temperature of 60 ℃ and retained 50.70% of its activity after incubation at 50 ℃ for 6 h, demonstrating good thermal stability. The EPS produced by strain C24202 showed strong emulsifying capacity, with an EI₂₄ value of 46.92%. FTIR analysis suggested that the EPS may be polymeric glycolipopeptide-type biosurfactants.Conclusion Strain C24202 possesses dual capabilities of producing thermostable lipase and biosurfactants, demonstrating promising potential for lipid degradation and the treatment of oil-containing wastewater.