Amrinder Singh1 Mukesh Kumar2 and Raj Kumar Salar1*
1Department of Biotechnology, Chaudhary Devi Lal University, Sirsa-125055, Haryana, India.
2Department of Biotechnology Engineering, Ambala College of Engineering and Applied Research, Devsthali-133101, Ambala, Haryana, India
A novel antimicrobial compounds producing strain of fungus was isolated from rhizospheric soil and identified as Aspergillus niger MTCC 12676 on the basis of morphological characters and molecular identification. Antimicrobial activity of this strain was evaluated by using different solvents against Gram positive bacteria Streptococcus mutans and Staphylococcus aureus, Gram-negative bacteria, Pseudomonas fluorescence and Escherichia coli and two yeast namely Candida tropicalis and Candida glabrata. Ethanol and ethyl acetate solvents exhibited significant antimicrobial activity against most of the tested microorganisms with more pronounced effect in case of ethyl acetate. MIC of ethanol extract ranged from 0.125-1.25 mg/ml whereas that of ethyl acetate was in the range of 0.312-0.0625 mg/ml. Antibiotic susceptibility pattern revealed that Staphylococcus aureus and Candida glabrata were resistant against the ciprofloxamine and fluconazole respectively. Combination of ciprofloxamine with different extracts (Ethanol and Ethyl acetate) exhibited synergistic effect in case of E. coli, P. fluorescence and S. mutans. Similarly, combination of the two extracts with antibiotic fluconazole had a positive synergistic effect in case of C. albicans.
Keywords: Aspergillus niger, Antimicrobial activity, MIC, Synergistic effect, rhizospheric soil.