Biotechnology for Biofuels
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2019
·Vol. 12
·期 1
·1-15
·
IF 5.452
Fang Wei,Xue Saisai,Deng Pengjun,Zhang Xuecheng,Wang Xiaotang,Xiao Yazhong,Fang Zemin
Background Starch is an inexpensive and renewable raw material for numerous industrial applications. However, most starch-based products are not cost-efficient due to high-energy input needed in traditional enzymatic starch conversion processes. Therefore, α-amylase with high efficiency to directly hydrolyze high concentration raw starches at a relatively lower temperature will have a profound impact on the efficient application of starch. Results A novel raw starch digesting α-amylase (named AmyZ1) was screened and cloned from a deep-sea bacterium Pontibacillus sp. ZY. Phylogenetic analysis showed that AmyZ1 was a member of subfamily 5 of glycoside hydrolase family 13. When expressed in Escherichia coli , the recombinant AmyZ1 showed high activity at pH 6.0–7.5 and 25–50 °C. Its optimal pH and temperature were 7.0 and 35 °C, respectively. Similar to most α-amylases, AmyZ1 activity was enhanced (2.4-fold) by 1.0 mM Ca 2+ . Its half-life time at 35 °C was also extended from about 10 min to 100 min. In comparison, AmyZ1 showed a broad substrate specificity toward raw starches, including those derived from rice, corn, and wheat. The specific activity of AmyZ1 towards raw rice starch was 12,621 ± 196 U/mg, much higher than other reported raw starch hydrolases. When used in raw starch hydrolyzing process, AmyZ1 hydrolyzed 52%, 47% and 38% of 30% (w/v) rice, corn, and wheat starch after 4 h incubation. It can also hydrolyze marine raw starch derived from Chlorella pyrenoidosa , resulting in 50.9 mg/g DW (dry weight of the biomass) of reducing sugars after 4 h incubation at 35 °C. Furthermore, when hydrolyzing raw corn starch using the combination of AmyZ1 and commercial glucoamylase, the hydrolysis rate reached 75% after 4.5 h reaction, notably higher than that obtained in existing starch-processing industries. Conclusions As a novel raw starch-digesting α-amylase with high specific activity, AmyZ1 efficiently hydrolyzed raw starches derived from both terrestrial and marine environments at near ambient temperature, suggesting its application potential in starch-based industrial processes.
研究领域:
生物化学
·
工业微生物学
·
酶工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Fuchang You,Yancheng Zheng,Xingguang Gong
As a key performance parameter of drilling fluids, filtration loss has received extensive attention. Although native starches have been proven to effectively control filtration, there are few comparative studies on native starches extracted from different plant sources. The objective of this study was to investigate the physicochemical properties of four native starches (wheat, corn, potato and cassava starches) and assess their effectiveness in filtration control within water-based drilling fluids, thereby elucidating the filtration control mechanisms of starch granules. Experimental results showed that after aging at temperatures ranging from 50 to 150 °C, potato starch exhibited good filtration control, achieving a minimum filtration loss of 4.0 mL. Amylopectin can directly affect the gelatinization temperature and internal structure of native starches, and gelatinized starch granules with a higher amylopectin content contain more active groups that interact with bentonite particles. These factors are the main reasons for the enhanced filtration control and temperature resistance of potato starch in water-based drilling fluids. The insights gained from this research on filtration control using native starches will promote the application and development of starches and their derivatives in water-based drilling fluids.
研究领域:
材料科学
·
石油工程
·
植物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
BIOCHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 4.446
He Li,Dongbang Yao,Jingru Ying,Xudong Han,Xuecheng Zhang,Xiuju Fang,Zemin Fang,Yazhong Xiao
A strategy that combines signal peptide (SP) optimization and translation efficiency improvement was used to enhance the extracellular production of raw starch-degrading α-amylase AmyZ1 from Pontibacillus sp. ZY in Bacillus subtilis . The optimal SP YpuA screened from 173 B. subtilis SPs mediated a 1.28-fold higher AmyZ1 activity than the original SP amyQ . Then, strategies of translation efficiency improvement, including optimizing the Shine-Dalgarno-like (SD-like) sequence, constructing a dual 5′-untranslated region (dual-UTR), optimizing the spacer region of the UTR, and optimizing the 5′-proximal coding sequence, were used to enhance AmyZ1 production. The resulting recombinant strain (BZYACO6) containing SD-like3, dUTR2, and an optimized 5′-proximal coding sequence (O6) produced the highest extracellular α-amylase activity of 2974.0 U/mL in shake flask, 2.07-fold higher than that of the original strain BZd34 (1437.6 U/mL). After fermentation optimization, the BZYACO6 strain produced an extracellular AmyZ1 activity of 3915.2 U/mL in shake flask and 25,070 U/mL in 3-L fermenter, representing the highest level of recombinant raw starch-degrading α-amylase production reported to date. Furthermore, this work provides a strategic reference for enhancing the extracellular production of other recombinant proteins in B. subtilis .
研究领域:
微生物学
·
生物技术
·
酶学
✓ 已验证
DOI
高影响因子
LWT-FOOD SCIENCE AND TECHNOLOGY
·
2021
·
IF 4.952
Lei Zhang,Lingli Zhong,Juying Wang,Yuqiang Zhao,Yiwei Zhang,Yitong Zheng,Weiliang Dong,Xianfeng Ye,Yan Huang,Zhoukun Li,Zhongli Cui
The process of raw starch conversion has attracted extensive attention in recent years due to its high energy conversion efficiency and saving of operational costs. In this study, extensive hydrolysis of raw starch by α-amylase AmyM from Corallococcus sp. EGB was investigated with robust substrate and products tolerance. AmyM showed broad substrate specificity toward raw starches with different types, and kept active and stable over a wide range of temperatures (30–70 °C) and pH values (5.0–9.0) and recycling. The V max values of AmyM towards wheat and corn raw starch were 1111 and 741 μmol/min/mg without depending on Ca 2+ , respectively. SEM analysis showed that AmyM hydrolysis results in the formation of porous and creviced surfaces around the starch granules peripheries. The cost-effective conversion of raw starch for the production of malto-oligosaccharides (MOSs) was identified. AmyM achieved high hydrolysis degree of 90% for 30% wheat and corn raw starch after 20 h at 45 °C with 5 U per mg of raw starch, resulting in formation of 70% MOSs and 30% dextrin. During this process, maltose (G2), maltotriose (G3) and maltotetraose (G4) were produced synchronously with G9 and G11, indicating the potential application in enzymatic conversion of raw starch under low temperature.
研究领域:
生物化学
·
酶学
·
食品科学
·
生物技术
✓ 已验证
DOI
高影响因子
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