Biological and microbiological activities of isolated Enterobacter sp. ACD2 exopolysaccharides from Tabuk region of Saudi Arabia

Several forms of bacterial exopolysaccharides (EPSs) have been reported as having industrial and medical benefits. Previously, our group had achieved a high yield of EPS production (8.6 gm/L) from Enterobacter sp. isolated from the marine environment of Haqel Beach, in the Tabuk region of Saudi Arabia, by optimizing its culture conditions. Then, the strain selected was identified using conventional methods and confirmed by molecular characterization that used 16S Ribosomal RNA (16S rRNA) gene sequencing. In the present study, we determined the composition of this EPS and evaluated its anticoagulation, fibrinolytic, antimicrobial, and prebiotic activities. We determined the monosaccharide moieties of this EPS using acid hydrolysis by qualitative and quantitative paper chromatography (PC). The monosaccharide composition of this EPS was almost 25% glucose, 25% galactose, 40% fucose, in addition to 10% uronic acid, with traces of fructose. Sulfation modification was applied to the EPS produced. The biological and microbiological (anticoagulation, fibrinolytic, antimicrobial, and prebiotic) activities of both the native and sulfated EPS were investigated and both exhibited higher antibacterial activity against Staphyllococcus aureus and Escherichia coli, although neither form displayed antifungal activity against Candida albicans. The minimum inhibitory concentration (MIC) of the native and sulfated EPS that sustained the highest bacterial inhibition zone was 15 mg/dl. No prebiotic activities were recorded for either EPS. In conclusion, the biopolymer produced has significant biological activities that require further adaptation for practical and industrial applications. (c) 2020 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Automated summary

The research team isolated Enterobacter sp. from the marine environment and produced a high yield of EPS, with its monosaccharide composition and sulfation modification enhancing its antibacterial activity against Staphylococcus aureus and Escherichia coli. However, the EPS showed no significant antifungal activity against Candida albicans and did not exhibit prebiotic activities. Further research and adaptation are needed for practical and industrial applications.