Amylase producing actinobacteria were isolated and characterized from terrestrial environment. There are a limited number of reports investigating the marine environment; hence, in the present study, four marine enzymes were tested for their amylase production ability. On starch agar plates, the Streptomyces rochei strain showed a higher hydrolytic zone (24 mm) than the other isolates. Growth under optimized culture conditions using Plackett-Burman’s experimental design led to a 1.7, 9.8, 7.7, and 3.12-fold increase for the isolates S. griseorubens, S. rochei, S. parvus, and Streptomyces sp., respectively, in the specific activity measurement. When applying the Box-Behnken design on S. rochei using the most significant parameters (starch, K2HPO4, pH, and temperature), there was a 12.22-fold increase in the specific activity measurement 7.37 U/mg. The α-amylase was partially purified, and its molecular weight was determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. α-Amylase was particularly active at pH 6 and 65°C. The purified enzyme was most active at 65°C and pH 6, thermal stability of 70°C for 40 min, and salt concentration of 1 M with Km and Vmax of 6.58 mg/ml and 21.93 μmol/ml/min, respectively. The α-amylase was improved by adding Cu+2, Zn+2, and Fe+2 (152.21%, 207.24%, and 111.89%). Increased production of α-amylase enzyme by S. rochei KR108310 leads to production of significant industrial products.

Background: Because of the ability of their bioactive metabolites production, many researchers were attracted to investigate and isolating marine actinomycetes from unique location with a unique environment. Information on antimicrobial activity and antifouling agents by Streptomyces sp. from the Ras Garib area, Gulf of Suez, Egypt is limited. One of the metabolites produced by the actinomycetes was biosurfactant. This paper describes the possibility of marine actinomycetes isolates for the production of biosurfactants, In addition to the possibility of using it as antimicrobial and antifouling agents.Results: Marine actinobacterial isolates RG3 and RG8 had emulsification indexes of 76 and 68%, respectively. The two marine actinobacterial isolates were identified using 16srDNA as Streptomyces althioticus RG3 and Streptomyces californicus RG8, and submitted in the database of genetic information with accession number MW661230 and MW661234, respectively. Biosurfactants were stable at 10% NaCl, in case of Streptomyces althioticus RG3 and stable at 10%–15% NaCl in the case of Streptomyces californicus RG8. A temperature of 35℃ was suitable for the stability of biosurfactants produced by both strains. Both strains produced the most biosurfactant when exposed to alkaline conditions. We characterized the biosurfactants produced by both strains including features such as the chemical composition of the biosurfactants and FTIR analysis. The antimicrobial activity of biosurfactants extract evaluated using a well diffusion method against Vibrio alginolyticus MK170250, Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 4027, and Staphylococcus aureus ATTC 25923. Streptomyces althioticus RG3 biosurfactants have been shown to have better antimicrobial activity than Streptomyces californicus RG8, indicating that they may be used in pharmaceutical industries and in the manufacture of antifouling products.Conclusions: Streptomyces althioticus RG3 and Streptomyces californicus RG8, isolated from Ras Garib, Gulf of Suez, Egypt, were able to develop very stable biosurfactants under stress conditions, which could be useful in a variety of industries such as pharmaceuticals and antifouling manufacturing.