Hunting for New Antibiotics from the Soil Bacteria of Tabuk Natural Reserves

Background: Antimicrobial resistance is spreading all over the world and at the same time the rate of discovery of antimicrobials in general and antibiotics in particular is diminished. Historically and currently many antibiotics are discovered and isolated from soil bacteria and other natural sources. In this project our aim is to search for antibiotic producing bacteria from soil samples.

Methods: Soil samples from different locations from King Salaman Bin Abdulaziz Royal Reserve were collected. Soil samples were cultured in Actinomyces special medium and incubated at 35 °C for 4 days. Isolates were further identified and categorized using VITEK-2 system. Two set of experiments were employed to evaluate the potential of antibiotic production and activity from these isolates against known pathogenic bacteria from both gram-positive and gram-negative Molecular identification of the isolates that exhibited inhibitory activity was performed by PCR. The identification of Actinomyces was confirmed or refuted molecularly by detecting the 16sRNA band in all the samples that were examined for their capacity to create inhibitory compounds.

Results: Many samples were identified through VITEK-2 as Actinomyces, others were unidentified and some were known irrelevant samples. Supernatant of the suspension of Actinomyces samples and the other unidentified samples succeeded to inhibit the growth of Staphylococcus aureus and Klebsiella pneumoniae in the checkerboard experiments.

Conclusion: Some of the isolates were Actinomyces that are potentially secreting inhibitory substances and some of them were Actinomyces but not producing inhibitory substances. Further research is recommended to characterize these inhibitory substances.