Purification and characterization of a salt-tolerant cellulase from the mangrove oyster, <italic>Crassostrea rivularis</italic>

Abstract

A cellulase with wide range of pH resistance and high salt tolerance was isolated from the digestive gland of the oyster Crassostrea rivularis living in mangrove forests. The 27 kDa cellulase named as CrCel was purified 40.6 folds by anion exchange chromatography and extraction from the gel after non-reducing sodium dodecylsufate-polyacrylamide gel electrophoresis. The specific activity of the purified cellulase was 23.4 U/mg against carboxymethyl cellulose (CMC). The N-terminal amino acid sequence of CrCel was determined to be NQKCQANSRV. CrCel preferably hydrolyzes β-1,4-glucosidic bonds in the amorphous parts of cellulose materials and displays degradation activity toward xylan. The K m and V max values of CrCel for CMC were determined to be 2.1% ± 0.4% and 73.5 ± 3.3 U mg −1 , respectively. The optimal pH value and temperature of CrCel were 5.5 and 40°C, respectively.The enzyme was stable in a wide range of pH, retaining over 60% activity after incubation for 80 min in the pH range of 3.0-9.0. In addition, CrCel showed remarkable tolerance to salt and remained active at high NaCl concentrations, but also retained over 70% activity after incubation in 0.5-2 M NaCl for up to 24 h. On the basis of the N-terminal sequence alignment and its similar properties to other animal cellulases, CrCel was regarded as a member of glycosyl hydrolase family 45 β-1,4-glucanases. CrCel is the first reported cellulase isolated from mangrove invertebrates, which suggests that it may participate in the assimilation of cellulolytic materials derived from the food sources of the oyster and contribute to the consumption of mangrove primary production. The unique properties of this enzyme make it a potential candidate for further industrial application.

A New Salt-Tolerant Thermostable Cellulase from a Marine Bacillus sp. Strain

“…5A). When pre-incubated for 1 h at different temperatures, the enzyme showed more than 40% of residual activity until 70°C, demonstrating considerable thermal stability when compared with other purified cellulases [8]. The purified enzyme showed the best activity at pH 6.5 (Fig.…”

“…After that, the sample was washed in distilled water for equal time, followed by soaking the gel for 3 h at 60°C in 0.05 M acetate buffer (pH 6.5). Subsequently, the gel was stained with 0.1% Congo-Red dye for 30 min and the excess dye was removed by 1 M NaCl until the appearance of clear bands demonstrating that CMC was hydrolyzed, as previously described [8].…”

“…Keywords: Sugarcane bagasse-degrading bacteria, thermostable enzymes, bioprocessing the reducing and non-reducing ends of cellulose to small glucose oligomers (cellobiose and cellodextrins), which in turn are hydrolyzed to single glucose units by enzymes denominated by β-glycosidases (E.C. 3.2.1.21) [8].…”

Effect of heat pretreatment before isoelectric solubilisation/precipitation on the characteristics of Pacific oyster (Crassostrea hongkongensis) and Antarctic krill (Euphausia superba) protein isolates

“…Solubility is the primary property of protein isolates because of its significant influence on the other functional properties of proteins. However, protein isolates are seriously affected by endogenous enzymes in the process of pH‐shifting protein extraction, especially those in shrimp and shellfish, which are rich in endogenous enzymes (Sun et al ., 2014; An et al, 2015). Such effects are not conducive to production control and product stability.…”

Isolation and Characterization of Thermophilic Enzymes Producing Microorganisms for Potential Therapeutic and Industrial Use

“…Susan found that Mucor-originated L-asparaginase activity was unaffected by the addition of 4% (w/v) NaCl 70 . Tianchen showed that the activity of Cellulase was moderately improved in the presence of 0.5-1 M NaCl and when NaCl concentration was progressively increased up to 4 M, the activity remained unchanged 71 .…”