芽孢杆菌A-30产碱性β-1,4-聚糖酶固体发酵研究

OPTIMIZATION OF CONDITIONS ON SOLID STATE FERMENTATION OF ALKALION β-l,4-GLYCANASE FROM BACILLUS SP. A-30

筛选得到一株高产β－１，４－聚糖酶的耐碱性芽孢杆菌Ａ－３０，其固体发酵（Ｓｏｌｉｄ ｓｔａｔｅ ｆｅｒｍｅｎｔａｔｉｏｎＳＳＦ）时最适培养条件：起始ｐＨ为８．０、培养温度３２℃、１０％（ｖ／ｗ）接种量，含水量为６６．６％（ｖ／ｗ），以０．５％的ＮａＮＯ_３为无机氮源，发酵９６ｈ，木聚糖酶活可达６４５７ＩＵ／ｇ（Ｄｒｙ ｂａｃｔｅｒｉａｌ ｂｒａｎ），纤维素酶活（ＣＭＣａｓｅ）可以达到１８．６６ＩＵ／ｇ。氮源组成、温度、ｐＨ及发酵时间等对Ａ－３０所产木聚糖酶和纤维素酶比例有较大影响。葡萄糖对Ａ－３０的阻遏效应不如在液体发酵（Ｓｕｂｍｅｒｇｅｄ Ｆｅｒｍｅｎｔａｔｉｏｎ ＳＭＦ）中明显，在６％的葡萄糖浓度下，Ａ－３０仍能够产生３５％以上的β－１，４－聚糖酶。

A strain A-30 which produced extracellular alkali-tolerant β-l,4-glycanase was screened and identified as Bacillus sp.. Its solid state fermentation (SSF) conditions which were optimized were as follows: 309 fresh medium in flake, initial pH8.0, temperature 32℃, 10% (v/w) inoculum, water concentration 66.6%, and fermentation period 96h, The xylanase astivity was as high as 6457IU/gDBB (dry bacterial bran) and CMCase activity amounted to 18.66IU/gDBB. Nitrogen sources, temperature, pH and culture time had great effects on the ratio of xylanase and CMCase. The repressive effect of glucose in SSF was not apparent as in Submerged Fermentation (SMF), when the concentration of glucose was so high as six percent the amount of β-l,4-glycanase produced from A-30 could exceed 35%.