AUTHOR=Xu Zhenshang , Kong Jian , Zhang Susu , Wang Ting , Liu Xinli 

TITLE=Comparison of Enzyme Secretion and Ferulic Acid Production by Escherichia coli Expressing Different Lactobacillus Feruloyl Esterases

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.568716

DOI=10.3389/fmicb.2020.568716

ISSN=1664-302X

ABSTRACT=<p>Construction of recombinant <italic>Escherichia coli</italic> strains carrying feruloyl esterase genes for secretory expression offers an attractive way to facilitate enzyme purification and one-step production of ferulic acid from agricultural waste. A total of 10 feruloyl esterases derived from nine <italic>Lactobacillus</italic> species were expressed in <italic>E. coli</italic> BL21 (DE3) to investigate their secretion and ferulic acid production. Extracellular activity determination showed all these <italic>Lactobacillus</italic> feruloyl esterases could be secreted out of <italic>E. coli</italic> cells. However, protein analysis indicated that they could be classified as three types. The first type presented a low secretion level, including feruloyl esterases derived from <italic>Lactobacillus acidophilus</italic> and <italic>Lactobacillus johnsonii</italic>. The second type showed a high secretion level, including feruloyl esterases derived from <italic>Lactobacillus amylovorus</italic>, <italic>Lactobacillus crispatus</italic>, <italic>Lactobacillus gasseri</italic>, and <italic>Lactobacillus helveticus</italic>. The third type also behaved a high secretion level but easy degradation, including feruloyl esterases derived from <italic>Lactobacillus farciminis</italic>, <italic>Lactobacillus fermentum</italic>, and <italic>Lactobacillus reuteri</italic>. Moreover, these recombinant <italic>E. coli</italic> strains could directly release ferulic acid from agricultural waste. The highest yield was 140 μg on the basis of 0.1 g de-starched wheat bran by using <italic>E. coli</italic> expressed <italic>L. amylovorus</italic> feruloyl esterase. These results provided a solid basis for the production of feruloyl esterase and ferulic acid.</p>