Abstract
Alginate-degrading bacteria or alginate lyases can be used to oligomerize alginate. In this study, an alginate-degrading bacterium with high alginolytic activity was successfully screened by using Sargassum fusiforme sludge. When the strain was grown on a plate containing sodium alginate, the transparent ring diameter (D) was 2.2 cm and the ratio (D/d) of transparent ring diameter to colony diameter (d) was 8.8. After 36 h in culture at a temperature of 28 °C shaken at 150 r/min, the enzymatic activity of the fermentation supernatant reached 160 U/mL, and the enzymatic activity of the bacterial precipitate harvested was 2,645 U/mL. The strain was named Cobetia sp. cqz5-12. Its genome is circular in shape, 4,209,007 bp in size, with a 62.36% GC content. It contains 3,498 predicted coding genes, 72 tRNA genes, and 21 rRNA genes. The functional annotations for the coding genes demonstrated that there were 181 coding genes in the genome related to carbohydrate transport and metabolism and 699 coding genes with unknown functions. Three putative coding genes, alg2107, alg2108 and alg2112, related to alginate degradation were identified by analyzing the carbohydrate active enzyme (CAZy) database. Moreover, proteins Alg2107 and Alg2112 were successfully expressed and exhibited alginate lyase activity.
Highlights
Alginate-degrading bacteria or alginate lyases can be used to oligomerize alginate
Thereafter, the polysaccharide substrate spectrum of the strain was verified based on genetic information. By considering both the crude enzyme experiments and the whole genome sequence information, researchers determined that sodium alginate can be thoroughly degraded by Algibacter alginolytica sp. novHZ22, and proposed that the structure and mechanism of polysaccharide utilization loci (PUL) be the goal of further r esearch[17]
When a colony of this strain formed on a solid plate containing sodium alginate, 1% calcium chloride was used to soak the colony for 30 min, and a transparent circle could be clearly observed around the colony (Fig. 1a)
Summary
Alginate-degrading bacteria or alginate lyases can be used to oligomerize alginate. In this study, an alginate-degrading bacterium with high alginolytic activity was successfully screened by using Sargassum fusiforme sludge. Thereafter, the polysaccharide substrate spectrum of the strain was verified based on genetic information By considering both the crude enzyme experiments and the whole genome sequence information, researchers determined that sodium alginate can be thoroughly degraded by Algibacter alginolytica sp. In order to select the most efficient alginate-degrading microorganism or alginate lyase for use in the industrial production of AOS, we needed to modify the present alginate-degrading microbe or alginate lyase, or else isolate a new, more efficient alginate-degrading microorganism, and purify a new alginate lyase from it For this purpose, the strain Cobetia sp. The complete genomic information about the strain was obtained, from which the coding gene sequences potentially related to alginate degradation were obtained and attempts were made to express these sequences. Further research can be performed using this data with the goals of understanding the degrading mechanism at the molecular level and, in turn, improving its alginolytic efficiency
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