Enhanced Chitin Deacetylase Production Ability of Rhodococcus equi CGMCC14861 by Co-culture Fermentation With Staphylococcus sp. MC7.

Qinyuan Ma,Min Wang,Xiuzhen Gao,Linna Tu,Yanbing Shen,Xing Zhang,Yabo Guo,Wenqin Yan,Qi Han

doi:10.3389/fmicb.2020.592477

Abstract

Chitin deacetylase (CDA) can hydrolyze the acetamido group of chitin polymers and its deacetylated derivatives to produce chitosan, an industrially important biopolymer. Compared with traditional chemical methods, biocatalysis by CDA is more environment-friendly and easy to control. However, most reported CDA-producing microbial strains show low CDA producing capabilities. Thus, the enhancement of CDA production has always been a challenge. In this study, we report co-culture fermentation to significantly promote the CDA production of Rhodococcus equi CGMCC14861 chitin deacetylase (ReCDA). Due to co-culture fermentation with Staphylococcus sp. MC7, ReCDA yield increased to 21.74 times that of pure culture of R. equi. Additionally, the enhancement was demonstrated to be cell-independent by adding cell-free extracts and the filtrate obtained by 10 kDa ultrafiltration of Staphylococcus sp. MC7. By preliminary characterization, we found extracellular, thermosensitive signal substances produced by Staphylococcus that were less than 10 kDa. We investigated the mechanism of promotion of ReCDA production by transcriptomic analysis. The data showed that 328 genes were upregulated and 1,258 genes were downregulated. The transcription level of the gene encoding ReCDA increased 2.3-fold. These findings provide new insights into the research of co-culture fermentation for the production of CDA and quorum sensing regulation.

Highlights

Chitin is the second most abundant biopolymer after cellulose, mainly obtained from waste products of the seafood industry, and is available at a relatively low cost (Grifoll-Romero et al, 2018)
We report co-culture fermentation to significantly promote the CDA production of Rhodococcus equi CGMCC14861 chitin deacetylase (ReCDA)
Its colony size was smaller than R. equi CGMCC14861, but the colony morphology was identical except for the colony color (Ma et al, 2020b)

Summary

Introduction

Chitin is the second most abundant biopolymer after cellulose, mainly obtained from waste products of the seafood industry, and is available at a relatively low cost (Grifoll-Romero et al, 2018). Chitosan is the deacetylated derivative of chitin (Raval et al, 2017), and it has gained broad interest in industrial applications owing to its unique features and physiological properties such as antimicrobial, antioxidant, and dilute acid-soluble property (Rinaudo, 2006; Younes and Rinaudo, 2015). Commercially available chitosan is still mainly produced by traditional chemical methods. They have many drawbacks such as being environmentally unsafe and poorly controlled in addition to the unstable nature of the products, especially in the deacetylation stage (Tsigos et al, 2000; Hamed et al, 2016). CDA is not commercially available due to the lack of potential microbial strains (Suresh et al, 2014)

Methods

Results

Conclusion