Enhanced chitinase production by <i>Chitinolyticbacter meiyuanensis</i> SYBC-H1 using staged pH control

Abstract

None of the authors of this manuscript has any financial or personal relationship with other people or organizations that could inappropriately influence their work.to their wide range of biotechnological applications, such as shellfish waste management (Nakagawa et al., 2011), generation of fungal protoplasts (Fleuri et al., 2009), production of single cell protein (Wang et al., 2006), production of N-acetyl-b-D-glucosamine (GlcNAc) and derivatives (Lin et al., 2009) and bio-control of fungal plant pathogens (Joo, 2005).Despite the potential commercial benefits, the application of chitinases has been limited by low productivity (Liu et al., 2013), which is of particular relevance to the production by the enzymatic degradation of chitin. Thus, increasing the levels of chitinase production is a key to improving GlcNAc production on an industrial scale. In a previous study, increasing the chitinase production , mainly via strain screening (Meena et al., 2013), strain mutation (Li et al., 2007), genetic modification (Iqbal et al., 2012) and medium optimization (Singh et al., 2013). Furthermore, the control of culture conditions, including the pH, was shown to be important for controlling the level of chitinase activity.The effect of pH on cell growth and enzyme production differs among microorganisms. Chitinase can be divided into alkaline (Bhushan and Hoondal, 1998), acidic (Chang et al., 2014), and neutral (Takeo et al., 2009) chitinase, according to its isoelectric point. The change of the growth medium pH owing to the accumulation of GlcNAc produced by the hydrolysis of chitin (Halder et al., 2013) does not benefit both cell growth and chitinase production in chitinase fermentation. However, there are few reports about the effect of pH on chitinase production in batch fermentation.A highly efficient chitinolytic bacterium Chitinolyticbacter meiyuanensis SYBC-H1 producing alkaline chitinase was isolated in our lab (Hao et al., 2011a, b;Zhang et al., 2016). In the present study, the influence Enhanced chitinase production by Chitinolyticbacter meiyuanensis SYBC-H1 using staged pH control (Received August 22, 2015 The pH of a microbiological culture is important for both cell growth and chitinase accumulation, but the optimal pH is not normally the same for both. The objective of this study was to investigate the effect of pH on chitinase production by Chitinolyticbacter meiyuanensis strain SYBC-H1 (ATCC BAA-2140) in a mineral medium. The results of batch culture at different pH values showed that the optimum pH for cell growth and chitinase production varied with time, although KOH produced the best results for cell growth and chitinase production, NaOH was chosen because of cost considerations. We designed a three-stage pH control strategy using NaOH as the neutralizing agent. Maximum cell growth (1.07 g dry cell weight/l) and maximum chitinase activity (13.6 U/ml) were observed after culture at 26∞C for 72 h in a mineral medium. These values were greater by 129% and 162%, respectively, and the length of time...

Molecular characterization of a novel chitinase CmChi1 from Chitinolyticbacter meiyuanensis SYBC-H1 and its use in N-acetyl-d-glucosamine production

“…Unless otherwise indicated, the enzyme reaction mixture containing the suitably diluted enzyme and different polysaccharide substrates at a final concentration of 10 g/L in 50 mM sodium citrate buffer (pH 5.2) was incubated for 30 min at 50 °C. The amount of reducing sugars was determined spectrophotometrically at 540 nm [ 15 ]. One unit of chitinase activity was defined as the amount of enzyme required to produce 1 μmol reducing sugar at 50 °C in 1 min.…”

“…The fermentative production of extracellular chitinases from strain SYBC-H1 was enhanced by optimization of culture condition and medium [ 14 ]. In previous studies, SYBC-H1 chitinases production was also optimized using a staged pH control strategy [ 15 ], and GlcNAc was produced from crude chitin powders using the chitinases from strain SYBC-H1 [ 16 ]. However, there are few reports about the coding genes, cloning, enzyme characteristics and catalytic characteristics of the chitinases from the family Neisseriaceae at present [ 17 , 18 ].…”

Identification of Chitinolytic Enzymes in Chitinolyticbacter meiyuanensis and Mechanism of Efficiently Hydrolyzing Chitin to N-Acetyl Glucosamine

“…SYBC-H1 was cultured according to our previous studies (Zhang et al, 2016a(Zhang et al, , 2018b. The genomic DNA was extracted using the TIANamp Bacteria DNA Kit (Tiangen Biotech Co., Ltd., Beijing, China).…”