ISSN: 0973-7510

E-ISSN: 2581-690X

Moustafa Y. El-Naggar1, Khouloud M. Barakat2 and Nawwara S. Aly1
1Botany & Microbiology Department, Faculty of Science, Alexandria University,
21511 Moharram Bey, Alexandria Egypt.
2Microbiology Lab., Marine Environment Div.,National Institute of Oceanography & Fisheries, Alexandria, Egypt.
J. Pure Appl. Microbiol., 2016, 10 (3): 1797-1808
© The Author(s). 2016
Received: 18/05/2016 | Accepted: 02/07/2016 | Published: 30/09/2016
Abstract

Fourteen actinomycete candidates were isolated from marine sediment (Mediterranean Sea, Alexandria, Egypt). The isolates were screened for their antagonistic activity against three Gram-positive (Staphylococcu aureus, Bacillus cereus and Micrococcus luteus) and three Gram-negative (Aeromonas hydrophila, Pseudomonas aeruginosa and Proteus sp) pathogenic bacteria. The most potent isolate was identified as Streptomyces chartreusis using 16S rRNA technology. Growth and antibacterial activity influencing parameters including culture medium, pH value and incubation temperature were all optimized using the procedures of response surface methodology.  The antibacterial activity was increased with the decrease in the pH level from seven to five and with the increase of temperature from 20 to 30oC. Maximum antibacterial activity (26.1 mm) was achieved after 4 days of incubation. A number of solvent systems have been experimented for the extraction of the bioactive compound(s). Ethyl acetate (EtOAc) crude extract showed highest activity against bacterial test strains with average inhibition zone diameter of 34.2 mm. The bio-toxicity of the crude extract showed a slight toxicity against the brine shrimp (Artemia salina). L.C50 was achieved at 1023 mg/l. The bioactivity of crude extract was superior to the activity exerted by the tested antibiotics (Amikacin, Amoxicillin/clavulanic acid; Chloramphenicol, Vancomycin, Erythromycin, Ciprofloxacin, Tetracycline). Based on data obtained by Fourier transform infrared spectrum (FT-IR) and gas chromatography – mass spectrum (GC-MS) and its library, the major compound was structurally identified as , cinnamaldehyde.

Keywords

S. chartreusis, Antagonistic activity, GC-MS, FT-IR, bio-toxicity, Cinnamamldehyde.

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© The Author(s) 2016. Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License which permits unrestricted use, sharing, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.