产脂肪酶菌株筛选及柠檬酸杆菌产酶条件优化

脂肪酶可以催化甘油三酯水解成脂肪酸和甘油，已广泛应用在工业领域，而获得产酶微生物是研究的基础。采用油脂平板法筛选出1株脂肪酶产生菌。经16S rRNA序列分析可知，该菌株属于柠檬酸杆菌(Citrobacter werkman and Gillen)。单因素试验对其进行产酶条件优化，优化后产酶条件（g/L）：淀粉2.0，KH₂PO₄ 1.0，K₂HPO₄·3H₂O 2.2，(NH₄)₂SO₄ 1.0，MgSO₄·7H₂O 0.1，牛肉膏2.0，橄榄油10.0 mL，pH 7.5，接种量1.5%(v/v)，37 ℃培养43 h。获得最大酶活为384 U/mL，是优化前的13倍。可以利用该菌制备脂肪酶。

Screening of Lipase Producing Bacteria and Conditions Optimization of Lipase Production by Citrobacter sp.

Lipase can catalyze hydrolysis of triglyceride into fatty acids and glycerol, and has been widely applied in industries, and to obtain lipase producing microorganisms is the basis of the study. A novel lipase producing microbe was isolated from lipid contaminated soil samples using plate screening method. It was purified and identified as Citrobacter sp. through 16S rRNA sequence analysis. The enzyme production condition was optimized by single factor experiment. The optimum culture condition was 2.0 (g/L, the same below) of soluble starch, 1.0 KH₂PO₄, 2.2 K₂HPO₄·3H₂O, 1.0 (NH₄)₂SO₄, 0.1 MgSO₄, 2.0 beef extract, olive oil 10 mL, pH 7.5 and 1.5% of inoculum, culture for 43 h at 37 °C in shaker. The obtained enzymatic activity was 384 U/mL at the highest, and it was 13 fold of that before the optimization. This strain could be used to produce lipase.