Cloning, expression and characterization of a novel salt-tolerant xylanase from Bacillus sp. SN5

Abstract

A xylanase gene (xyn10A) was cloned from Bacillus sp. SN5 and expressed in Escherichia coli. It encoded a 348-residue polypeptide of ~45 kDa. The deduced amino acid sequence had 68 % identity with the endo-1,4-beta-xylanase from Paenibacillus lactis 154 that belonged to family 10 of the glycoside hydrolases. Purified recombinant Xyn10A had maximum activity at 40 °C and pH 7.0, with the specific activity of 105 U/mg and a Km of 0.6 mg/ml for beechwood xylan. Xyn10A retained more than 80 % activity between 25 and 45 °C and 29 % activity at 5 °C. It exhibited the highest activity (134 %) in 0.5 M NaCl and still retained 90 % activity in 2.5 M NaCl. It retained about 87 % activity after incubation in 2 M NaCl for 24 h. The cold-active and halo-tolerant properties of Xyn10A make it promising for application in the food industry, especially in the processing of saline food and sea food.

Characterization of a Salt-Tolerant and Cold-Adapted Xylanase from Bacillus cellulosilyticus

“…The results showed differences from the other cold-adapted xylanases, such as xylanases from Bacillus sp. SN5 and G. mesophila KMM241 (Guo et al 2009;Bai et al 2012), which showed that Mg 2+ had no evident effect on activity. On the contrary, the activity of XynB from G. mesophila KMM241 was obviously inhibited by Mn 2+ (Guo et al 2009).…”

“…The xylanases from Glaciecola mesophila (Guo et al 2009), Bacillus sp. SN5 (Bai et al 2012), Zunongwangia profunda (Liu et al 2014), and goat rumen contents belonging to the GH10 family showed obvious cold-adapted activity (Wang et al 2011). Additionally, several xylanases from G. mesophila KMM241 (Guo et al 2013), Pseudoalteromonas haloplanktis (Petegem et al 2003), and the environmental DNA library of lagoons (Lee et al 2006) belonging to the GH8 family also exhibited the cold activity.…”

“…Xyn10A showed the highest sequence similarity (67%) to the xylanase from Bacillus akibai (Accession number WP_035668525.1) and the highest identity (61%) to the xylanase from Bacillus sp. SN5, among the characterized xylanases (Bai et al 2012). Fig.…”

“…The xylanases from Bacillus sp. SN5 (Bai et al 2012) showed the highest similarity (61%) with Xyn10A among characterized xylanases. Its optimum pH was 7.0 and not especially alkaline, though Bacillus sp.…”

“…Its optimum pH was 7.0 and not especially alkaline, though Bacillus sp. SN5 (Bai et al 2012) was the alkaliphilic strain. Compared with the other reported cold-adapted xylanases, only Xyn10A displayed the optimum activity at alkaline conditions.…”