脂肪酶菌株筛选、产酶条件优化及粗酶性质研究

Screening of lipase-producing strains and studies on cultivation conditions & properties of crude lipase

从西藏传统食品中分离出一株生产胞外脂肪酶的菌株,通过分子鉴定和形态观察,确定其为黑曲霉AN0512.本文优化了AN0512的产酶条件,并研究了粗酶性质.结果表明,采用植物油1%(v/v)、酵母提取物1%(w/w)、KH2PO40.2%(w/w)、MgSO40.05%(w/w)、KCl0.05%(w/w)等组成的培养基,接种量为1.5%(v/v)时,在28℃、180r/min下培养96h后,发酵液中脂肪酶活性最大达到30IU/mL.在30℃、pH7.0的酶反应条件下粗酶的脂肪酶活性达到最大;在60℃时粗酶仍保留60%以上的脂肪酶活性,显示其较好的耐热性;Ca2+、Fe2+、Co2+、Mg2+、Mn2+能促进粗酶的活性,其中Fe2+的促进作用最大.粗酶液中应含有活性较高的、耐热的低温金属脂肪酶.

An extraeellular lipase-produeing strain,which is identified as Aspergillus niger AN0512 by 18s rRNA sequence analysis and morphology observation, is screened from traditional food in Tibet. The cultivation conditions for lipase production of AN0512 are optimized, and properties of the crude li pase are studied. The optimal fermentation conditions for lipase production are as followings： seed oil 1% （v/v）, yeast extract powder 1%（w/w）, KHzPO4 0.2%（w/w）,MgSO4 0.05%（w/w）,KC1 0.05% （w/w）, inoculum size 1.5 （v/v）, under which the highest enzyme activity can be achieved to 30 IU/ mL at 28 Cand 180 r/min for 96h. The maximal enzyme activity of the crude lipase is achieved at the condition of 30℃ and pH 7.0. The crude lipase is heat-resistant for it can even be retained for more than 60% enzyme activity at 60 ℃. Ca2＋ , Fe2＋ , Co2＋ , Mg2＋ , and Mn2＋ activate the crude lipase and Fe2＋ has the greatest activation effect. It is implied that highly active, heat-resistant and cold-adaptedmetallo-lipase may be included in the crude enzyme.