ORCID Profile
0000-0002-7957-620X
Current Organisation
Chiang Mai University
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Publisher: Elsevier BV
Date: 05-2019
DOI: 10.1016/J.PEP.2019.01.005
Abstract: Lactobacillus pentosus BA-7 and L. pentosus QA1-5 are tannin-tolerant lactic acid bacteria that were isolated from Miang, a traditional fermented tea-leaf found in northern Thailand and a tannin-rich substrate. Tannase encoding genes were isolated, cloned and overexpressed in Escherichia coli BL21(DE3). The recombinant tannase was produced with production yields of 40 and 39 KU/L for LpTanBA-7 and LpTanQA1-5, respectively. Both revealed the same molecular weight of 50 kDa as estimated by SDS-PAGE and were optimally active under alkaline pH conditions LpTanQA1-5 revealed optimal temperatures in a range of 37-40 °C as is typically found in lactic acid bacteria, while LpTanBA-7 was active at higher temperatures with an optimum temperature range of 45-55 °C. LpTanBA-7 was found to be more stable within the same range of temperatures than LpTanQA1-5. Furthermore, it was active and stable toward various organic solvents and produced 50 mg/mL of gallic acid from 100 mg/mL tannic acid. Based on the results, LpTanBA-7 is considered a new alkali-moderately thermophilic tannase obtained from lactic acid bacterium that may be capable of a feasible production capacity of gallic acid and its esters. Furthermore, tannase that is active at high temperatures could also be used in tea products in order to develop a sweet aftertaste, as well as to improve levels of antioxidant activity.
Publisher: Frontiers Media SA
Date: 14-06-2021
DOI: 10.3389/FMICB.2021.689413
Abstract: Lactic acid bacteria (LAB) have been used as starter cultures and producers of enzymes, antimicrobial peptides or metabolites that contribute to the flavor, texture and safety of food products. Lactiplantibacillus plantarum , one of the best-studied LAB, is considered as safe and effective cell factory for food applications. In this study, our aim was to use L. plantarum as the producer for high levels of a food-grade lactobacillal α-amylase, which has potential applications in food, fermentation and feed industries. The native form of an α-amylase (AmyL) from L. plantarum S21, an amylolytic LAB isolated from Thai fermented rice noodles, was expressed in L. plantarum WCFS1 using the pSIP expression system. The secretion of the α-amylase was driven by the native signal peptides of the α-amylases from L. plantarum S21 (SP_AmyL) and Lactobacillus amylovorus NRRL B-4549 (SP_AmyA), as well as by three Sec-type signal peptides derived from L. plantarum WCFS1 Lp_2145, Lp_3050, and Lp_0373. Among the tested signal peptides, Lp_2145 appears to be the best signal peptide giving the highest total and extracellular enzymatic activities of α-amylase AmyL from L. plantarum S21, which were 13.1 and 8.1 kU/L of fermentation, respectively. These yields were significantly higher than the expression and secretion in L. plantarum WCFS1 using the native signal peptide SP_AmyL, resulting in 6.2- and 5.4-fold increase in total and extracellular activities of AmyL, respectively. In terms of secretion efficiency, Lp_0373 was observed as the most efficient signal peptide among non-cognate signal peptides for the secretion of AmyL. Real-time reverse-transcriptase quantitative PCR (RT-qPCR) was used to estimate the mRNA levels of α-amylase transcript in each recombinant strain. Relative quantification by RT-qPCR indicated that the strain with the Lp_2145 signal peptide-containing construct had the highest mRNA levels and that the exchange of the signal peptide led to a change in the transcript level of the target gene.
Publisher: Elsevier BV
Date: 02-2018
DOI: 10.1016/J.IJBIOMAC.2017.09.060
Abstract: Gene encoding cyclomaltodextrinase (Cdx) from amylolytic lactic acid bacterium Enterococcus faecium K-1 was cloned and nucleotide sequence was analyzed. The open-reading frame consisted of 1767bp encoding 588 deduced amino acids. Consequently, four typically conserved regions of the glycoside hydrolase family 13 were revealed however, nine exceeding amino acids (DSYQMTDVP) were found at the 282-290 position in comparison to previously reported cyclomaltodextrinases. This difference is believed to have an influence on the substrate specificity of this enzyme. The recombinant CDases expressed in Escherichia coli BL21 (CDX_E) and Lactobacillus plantarum WCFS1 (CDX_L) with high expression levels of 8041 and 5511U/L were purified by Ni-NTA affinity chromatography. The active form CDX is a dimeric protein with two identical subunits of 62kDa, approximately. Both CDX_E and CDX_L revealed nearly similar properties, but the thermostability of CDX_L was slightly higher. Mn
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