PT  - JOURNAL ARTICLE
AU  - Matthew Barcus
AU  - Dario Mizrachi
AU  - Xin Gen Lei
TI  - Identification and kinetics characterization of a wax ester hydrolase from a feather-degrading actinomycete
AID  - 10.1101/178673
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 178673
4099  - http://biorxiv.org/content/early/2017/08/21/178673.short
4100  - http://biorxiv.org/content/early/2017/08/21/178673.full
AB  - Streptomyces fradiae var. k11 is a Gram-positive soil microorganism capable of degrading chicken feathers. Apart from being mostly protein, chicken feathers have a considerable level of lipids, with wax esters being the largest lipid class. The waxes may pose a challenge while rendering the feathers into coproducts, such as feather meal, and so the identification of a wax-ester hydrolase is warranted. A draft genome sequence of S. fradiae var. k11 was used to identify 14 gene sequences of potential lipid-degrading enzymes. The genes were expressed in E. coli BL21(DE3) cells on a pET vector and screened for activity. Four of the 14 enzymes had detectable activity, with two of the enzymes, SFK3309 and SFK3087, active against p-nitrophenyl palmitate, a representative water-insoluble substrate. A modified enzymatic assay was designed to measure activity against three model wax substrates: jojoba oil, beeswax, and cetyl-palmitate. SFK3309 was characterized to hydrolyze all three wax substrates. Kinetic experiments for SFK3309 were performed with cetyl-palmitate at 37°C, pH 8.0. The Km was determined to be 850 µM and the Kcat was 11.63 s-1. Through the characterization of SFK3309 as a wax-ester hydrolase, biotechnological implications of wax ester hydrolases in the rendering of many industrial wastes can be substantiated for further studies.