Marine urease with higher thermostability, pH and salinity tolerance from marine sponge-derived Penicillium steckii S4-4

Urease has a broad range of applications,however,the current studies on urease mainly focus on terrestrial plants or microbes.Thus,it is quite necessary to determine if marine-derived ureases have diferent characteristics from terrestrial origins since the fnding of ureases with superior performance is of industrial interest.In this study,the marine urease produced by Penicillium steckii S4-4 derived from marine sponge Siphonochalina sp.was investigated.This marine urease exhibited a maximum specifc activity of 1542.2 U mg protein−1.The molecular weight of the enzyme was 183 kDa and a single subunit of 47 kDa was detected,indicating that it was a tetramer.The N-terminal amino acid sequence of the urease was arranged as GPVLKKTKAAAV with greatest similarity to that from marine algae Ectocarpus siliculosus.This urease exhibited a K_(m) of 7.3 mmol L^(−1) and a V_(max) of 1.8 mmol urea min^(−1) mg protein^(−1).The optimum temperature,pH and salinity are 55℃,8.5 and 10%,respectively.This urease was stable and more than 80%of its maximum specifc activity was detected after incubating at 25–60℃for 30 min,pH 5.5–10.0 or 0–25%salinity for 6 h.Compared with the terrestrial urease from Jack bean,this marine urease shows higher thermostability,alkaline preference and salinity tolerance,which extends the potential application felds of urease to a great extent.