Antimicrobial Activity of Marine Actinomycetes and the Optimization of Culture Conditions for the Production of Antimicrobial Agent(s)

Abstract

Citation: Moaz M. Hamed, Lamis Sh. Abdelfattah and Nayer M. Fahmy, Antimicrobial Activity of Marine Actinomycetes and the Optimization of Culture Conditions for the Production of Antimicrobial Agent(s), J Pure Appl Microbiol., 2019; 13(4):2177-2188. Abstract The aim of the present study was to isolate antagonistic actinomycetes from marine sediment collected from the Red Sea coast at Hurghada city and the Suez Gulf. A total of 16 actinomycete isolates were obtained in October 2018 and their antagonistic activities were evaluated against Aeromonas hydrophila, Vibrio damsela, Staphylococcus aureus ATCC6538, Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa ATCC 9027, Salmonella typhimurium ATCC 14028, Escherichia coli ATCC 19404 and Candida albicans ATCC 10231 by using the agar well diffusion method. Among the 16 isolates, 14 (87.5%) isolates exhibited antimicrobial activity against most of the tested pathogens. The most potent isolate was identified by 16S rRNA sequence analysis as Streptomyces sp. and designated Streptomyces sp. MK388207. The experimental design of Plackett-Burman was implemented to optimize the culture conditions for antimicrobial agent(s) production by the most powerful isolate against C. albicans ATCC 10231 when grown in starch nitrate broth and the data revealed that negative (-) levels of KNO 3 , K 2 HPO 4 and pH and positive (+) levels of starch, MgSO 4 .7H 2 O, FeSO 4 and incubation period supported the production of the antimicrobial agent(s). Growth under the optimized culture conditions led to a 1.4-fold rise in antimicrobial activity. The ethyl acetate extract of Streptomyces sp.MK388207 was subjected to gasliquid chromatography mass spectrometry (GC MS) and revealed the presence of six fractions with the major component being phenol, 2,4-bis (1,1 dimethylethyl). The findings of this study suggested that the antagonistic marine Streptomyces, in particular Streptomyces sp MK388207, the antibacterial compounds produced by this isolate, could be used as antibiotics that could have future applications in the pharmaceutical industry.

Production and Partial Characterization of α-Amylase Enzyme from Marine Actinomycetes

“…Streptomyces griseorubens strain (MMH 9) [ 17 ], Streptomyces rochei strain (HMM 13) [ 18 ], Streptomyces parvus strain (8) [ 19 ], and Streptomyces sp. strain (M12) [ 20 ] were isolated from marine sediment samples in the Gulf of Suez and deposited in Genbank with accession numbers KR133201, KR108310, KP675949, and MK388207, respectively, by Dr. Moaz M. Hamed. These marine actinobacterial isolates were maintained on a slant containing starch nitrate agar medium (SNM) with a specific composition per liter: 20 g of starch, 1 g of K 2 HPO 4 , 2 g of KNO 3 , 0.5 g of MgSO 4 , and 18 g of agar.…”

Bioactivity of Metabolites from Actinomycetes Isolates from Red Sea, Egypt

“…In a multivariable scheme, statistical experimental designs are the most effective strategies for quickly identifying significant variables, and for reducing errors in assessing the impact of diverse factors [8,33,34]. We evaluated the influence of starch nitrate medium on the synthesis of antimicrobial agents from S. qinglanensis H4 against S. aureus ATCC6538 by using Plackett-Burman design.…”

“…Hamed et al 2019 reported that, increasing starch and MgSO 4 concentrations led Streptomyces sp. MK388207 to enhance antagonistic activity by about 1.4-fold against C. albicans ATCC 10231 [8]. Another study by [35] reported that increasing the incubation length, peptone, inoculum size, temperature, pH, and saltwater concentration by Enterococcus faecium enhanced the inhibition zone by roughly 1.6 times.…”

“…The only option to solve this issue is to continue the hunt for new antibiotics, particularly in environments that have received less attention. Microorganisms originating from many marine sources provide potential antibacterial compounds that might be utilized to treat numerous infectious ailments and could eventually replace conventional medications [8]. As the number of new bioactive compounds discovered by terrestrial actinomycetes decreases, a substantial amount of study has been focused on screening actinomycetes from various environments for their capacity to produce new secondary metabolites.…”

“…Because of this, microbial isolates could produce more bioactive chemicals if nutritional and physical parameters were altered throughout the incubation phase. Surface approach and the Plackett-Burman experimental design are employed to construct the nutritional circumstances, and by optimizing all impacting parameters together, the feasibility of a single-factor optimization is removed [8].…”