Abstract
The marine ecosystem is one of the richest sources of biologically active compounds, such as enzymes, among which seaweed is one of the most diverse marine species and has a rich diversity of bacteria that produce different enzymes. Among these, the bacteria-derived xylanase enzyme has many applications in the fruit juice, paper, and baking industries; so, to consider the economic value of the xylanase enzyme and the isolation and identification of xylanase-producing bacteria is of particular importance. In this study, specimens of the alga Ulva flexuosa species were collected from the coasts of Bandar Abbas and Qeshm Island. The bacteria coexisting with the algae were isolated using a nutrient agar medium. The bacteria producing the xylanase enzyme were then screened by a specific solid culture medium containing xylan, and the activity of the xylanase enzyme isolated from the bacteria was measured using a xylan substrate. The bacteria with the highest enzymatic activity were selected and identified by 16S rRNA gene sequence analysis, and the culture medium conditions for the enzyme production by the selected bacterial strains were optimized. Among the bacterial community, two strains with the highest xylanase activity, which belonged to the genera Bacillus and Shewanella, were identified as Bacillus subtilis strain HR05 and Shewanella algae strain HR06, respectively. The two selected bacteria were registered in the NCBI gene database. The results demonstrated that the two selected strains had different optimal growing conditions in terms of pH and temperature, as well as the sources of carbon and nitrogen for enzyme production. It seems that the xylanase enzyme isolated from the bacterial strains HR05 and HR06, which coexist with alga Ulva flexousa, could be potential candidates for biotechnology and various industries, such as pulp production, paper, and food manufacture, due to their high activity and optimal alkaline pH.