Šokarda Slavić Marinela, Pešić Milja, Vujčić Zoran, Božić Nataša
Centre of Chemistry, Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Studentski trg 12-16, Belgrade, 11000, Serbia.
Department of Biochemistry, Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, Belgrade, 11000, Serbia.
Appl Microbiol Biotechnol. 2016 Mar;100(6):2709-19. doi: 10.1007/s00253-015-7101-4. Epub 2015 Nov 7.
α-Amylase from Bacillus licheniformis ATCC 9945a (BliAmy) was proven to be very efficient in hydrolysis of granular starch below the temperature of gelatinization. By applying two-stage feeding strategy to achieve high-cell-density cultivation of Escherichia coli and extracellular production of BliAmy, total of 250.5 U/mL (i.e. 0.7 g/L) of enzyme was obtained. Thermostability of amylase was exploited to simplify purification. The hydrolysis of concentrated raw starch was optimized using response surface methodology. Regardless of raw starch concentration tested (20, 25, 30 %), BliAmy was very effective, achieving the final hydrolysis degree of 91 % for the hydrolysis of 30 % starch suspension after 24 h. The major A-type crystalline structure and amorphous domains of the starch granule were degraded at the same rates, while amylose-lipid complexes were not degraded. BliAmy presents interesting performances on highly concentrated solid starch and could be of value for starch-consuming industries while response surface methodology (RSM) could be efficiently applied for the optimization of the hydrolysis.
地衣芽孢杆菌ATCC 9945a（BliAmy）的α-淀粉酶被证明在糊化温度以下对颗粒淀粉的水解非常有效。通过采用两阶段补料策略实现大肠杆菌的高密度培养和BliAmy的胞外生产，共获得了250.5 U/mL（即0.7 g/L）的酶。利用淀粉酶的热稳定性简化纯化过程。使用响应面法优化了浓缩生淀粉的水解。无论测试的生淀粉浓度如何（20%、25%、30%），BliAmy都非常有效，在24小时后，30%淀粉悬浮液的水解最终水解度达到91%。淀粉颗粒的主要A型晶体结构和无定形区域以相同的速率降解，而直链淀粉-脂质复合物未被降解。BliAmy在高浓度固体淀粉上表现出有趣的性能，对于淀粉消耗行业可能具有价值，而响应面法（RSM）可有效地用于水解的优化。
