Isolation, identification and evaluation of the anti-diabetic activity of secondary metabolites extracted from bacteria associated with the Persian Gulf sponges (Haliclona sp. and Niphates sp.)

Sponge-associated bacteria have a special position in marine biotechnology due to their unique biological activities. The main objective of this study was to isolate and identify the bacteria associated with sponges around Qeshm Island, Iran, which inhibit the activity of alpha-glucosidase and alpha-amylase enzymes by the produced metabolites. Samples were collected from sponge species living in the study area, including the genera Haliclona and Niphates. Isolation was performed using culture-dependent techniques. A total of 155 bacterial isolates were collected. The diversity pattern of bacteria in the sponge samples showed that the Vibrio and Bacillus constituted the predominant bacterial population. The assessment of alpha-glucosidase inhibitory activity of metabolites extracted from the isolated bacteria showed that 6 isolates could inhibit the enzyme activity with IC50 values ​​ranging from 153.5 to 495.4 μg/ml, while 9 bacterial isolates inhibited the activity of alpha-amylase enzyme in IC50 values ​​at the range of 112.9 to 670.9 μg/ml. The cytotoxic activity of the metabolites extracted on human umbilical cord endothelial cells showed the toxicity of the three extracts at effective concentrations, while seven isolates showed no toxicity. Genetic identification indicated 97% to 100% similarity of the potent isolates with the NCBI gene bank including Bacillus pumilus, Bacillus safensis, Vibrio alginolyticus, Pseudomonas stutzeri, Vibrio parahaemolyticus, Pseudomonas lurida, Bacillus tequilensi, and Streptomyces enissocaesilis. The results of this study provided a new understanding of the diversity pattern of cultivable sponge-associated bacteria and their inhibitory activity on alpha glucosidase and alpha amylase enzymes.