ABSTRACT
Background: Streptomyces levis is a member of Actinomycetes family. Chemical compounds extracted from this bacterium have been used as antibiotics, anti-tumoral, anti-bacterial, anti-fungal, antiviral, anticancer factors. The purpose of this study was to investigate different metabolites of Streptomyces strains isolated from north west soils, of Iran and antimicrobial effects of them
Methods: The soil samples were taken from north west of Iran in 2010. The isolated bacteria were purified and identified by conventional methods. The metabolites of this bacterium were extracted by 7 different solvents [diethyl ether, dichloromethane, hexane, ethyl acetate, chloroform, methanol and water]. The antimicrobial effects of metabolites were tested by disk agar diffusion method on Gram-positive and Gram- negative bacteria. The metabolites with antibacterial effects were analyzed by gas chromatography-mass spectrometry [GC-MS]
Results: Metabolites produced from diethyl ether solvent affected Gram- positive and Gram- negative strains and 15 different compounds identified in the active metabolite of the bacterium. The main ingredients were: Docosanoic acid, methyl ester [11.578%], 9-12-octadecadienoic acid [2.961%], 5-Tetracosenois acid, methyl ester [8.389%], Bis [2-ethylhexyl] phthalate [2.153%], and D-alpha-Tocopherol [0.959%]
Conclusion: Results of this study showed that docosanoic acid, methyl ester [11.578%] and 5-tetracosenois acid methyl ester [8.389%], were the main metabolites of Streptomyces levis isolated from north west soils of Iran. Antimicrobial effects of extracts could be due to the presence of 1, 2-benzene dicarboxylic acid diisooctyl ester compounds and bis [2-ethylhexyl] phthalate in the metabolite
ABSTRACT
In this study, lactic acid production by repeated batch fermentation using cell entrapped methods was compared. Barium alginate beads, agar gel and polyurethane foam cubes were employed as carriers to immobilize Lactobacillus casei subsp. casei for the purpose of L [+]-lactic acid production. Increasing concentrations of lactic acid during fermentation were better tolerated by barium alginate entrapped cells. Alginate beads had a considerable effect on lactic acid production and reduced the fermentation time by half. The volumetric productivity with barium alginate and agar immobilized cells were 0.625 and 0.425 [g/lh] respectively, whereas it was 0.375 [g/lh for conventional free-cell fermentation. Beside biocompatibility, barium alginate immobilized cells exhibited good mechanical strength during repetitive fermentations and could be used in repetitive batch cultures for more than 40 days. The novelty of this study is lactic acid production by repeated batch fermentation with immobilized L. casei using polyurethane foam [PUF] in an economical culture medium composed of whey and corn steep liquor supplemented by glucose