Optimization of xylanase production using inexpensive agro-residues by alkalophilic Bacillus subtilis ASH in solid-state fermentation
Optimization of xylanase production using inexpensive agro-residues by alkalophilic Bacillus subtilis ASH in solid-state fermentation
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DOI：
10.1007/s11274-007-9521-5
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发表时间：
2008-05-01
影响因子：
4.1
通讯作者：
Gupta, Vijay K.
中科院分区：
文献类型：
--
作者：
Sanghi, Ashwani;Garg, Neelam;Gupta, Vijay K.
嗜碱枯草芽孢杆菌（Bacillus subtilis）ASH利用麦麸、麦秸、稻壳、锯末、麦麸、花生和玉米麸皮等廉价易得的农业废渣进行固态发酵，生产出高水平的木聚糖酶。其中麦麸是最佳的发酵基质。在37 ° C和1：2（w/v）的底物与水分比下孵育72小时后，木聚糖酶产量最高。15%的接种量导致木聚糖酶的最大产量。通过添加酵母膏、蛋白胨和牛肉膏等营养物质来刺激酶的产生。相比之下，添加葡萄糖和木糖抑制了木聚糖酶的产生。葡萄糖（10%，w/v）的抑制程度为81%，它是浓度依赖性的。补充4%木糖的培养基引起59%的阻遏。在优化条件下，SSF中木聚糖酶的产量（8，964 U木聚糖酶/g干麦麸）比深层发酵高约两倍。因此，B。枯草芽孢杆菌使用廉价的农业残留物在SSF中产生非常高水平的木聚糖酶，该水平远高于任何其它细菌分离物所报道的水平。此外，该酶在室温下和自来水中产生，而无需在SSF中添加任何矿物盐，从而显著降低了木聚糖酶的生产成本，这增强了其工业潜力。
Alkalophilic Bacillus subtilis ASH produced high levels of xylanase using easily available inexpensive agricultural waste residues such as wheat bran, wheat straw, rice husk, sawdust, gram bran, groundnut and maize bran in solid-state fermentation (SSF). Among these, wheat bran was found to be best substrate. Xylanase production was highest after 72 h of incubation at 37 degrees C and at a substrate to moisture ratio of 1:2 (w/v). The inoculum level of 15% resulted in maximum production of xylanase. The enzyme production was stimulated by the addition of nutrients such as yeast extract, peptone and beef extract. In contrast, addition of glucose and xylose repressed the production of xylanase. The extent of repression by glucose (10%, w/v) was 81% and it was concentration-dependent. Supplementation of the medium with 4% xylose caused 59% repression. Under optimized conditions, xylanase production in SSF (8,964 U of xylanase/g dry wheat bran) was about twofold greater than in submerged fermentation. Thus, B. subtilis produced a very high level of xylanase in SSF using inexpensive agro-residues, a level which is much higher than that reported by any other bacterial isolate. Furthermore, the enzyme was produced at room temperature and with tap water without the addition of any mineral salt in SSF, leading to a marked decrease in the cost of xylanase production, which enhances its industrial potential.