Development of enzyme cocktails for complete saccharification of chitin using mono-component enzymes from Serratia marcescens

One potential strategy for biorefining of chitin-rich biomass entails enzymatic saccharification, which, so far, has been scarcely explored. Here, saccharification of chitin was explored using response surface methodology available in the MODDE^®10 software, to develop optimal cocktails of five mono-component enzymes from Serratia marcescens, three chitinases, SmChiA, SmChiB, SmChiC, a lytic polysaccharide monooxygenase, SmLPMO10A (or “CBP21”), and a beta-N-acetylhexosaminidase, SmCHB (“chitobiase”). These five enzymes were recombinantly produced in Escherichia coli. For both shrimp and crab chitins, SmChiA was the most abundant (40% and 38%, respectively) in the optimized cocktails, whereas SmChiB, SmChiC and SmLPMO10A were present at 30% and 26%, 15% and 23%, and 3% and 2%, respectively. Saccharification yields were 70%–75%, whereas a “minimal” cocktail of SmChiA and SmCHB gave only 40% saccharification. These results show that enzymatic saccharification of chitin requires multiple enzyme activities applied at dosages similar to those used for saccharification of cellulose.