The global antibiotic crisis is driven by the rapid emergence of bacterial resistance, necessitating innovative approaches to discover novel antibiotics. Soil bacteria, known for producing antibiotics to outcompete neighbors, represent a promising source of antimicrobial compounds. In this study, soil samples from a dry, gravelly area of the Brackenridge Field Laboratory (30.28359°N, -97.77945°W) were analyzed to identify potential antibiotic-producing bacteria. Serial dilutions yielded a microbial density of 123 and 58 CFUs on 10^-1 and 10^-2 plates, respectively. Co-culturing with E. coli and E. raffinosus revealed that 18.75% of isolates inhibited E. coli, while 6.25% inhibited E. raffinosus.
Isolate 3 exhibited dual resistance to Ampicillin and E. coli, making it a standout candidate for further investigation. Morphological, physiological, and metabolic characterization revealed diverse traits among isolates, including motility, lactose fermentation, and distinct colony morphologies. PCR confirmed successful DNA amplification in isolates 3 and 4, while Gram staining classified isolates as both Gram-positive and Gram-negative. Metabolic profiling highlighted unique properties, such as catalase activity in isolates 3 and 4 and beta-hemolysis in isolate 4, indicating potential clinical or ecological significance.
Despite limited antibiotic production, the findings highlight the resilience and adaptive capabilities of soil bacteria in arid environments, particularly in nutrient-limited conditions. The study emphasizes the importance of further research into environmental factors influencing antibiotic production and resistance. By exploring the biochemical diversity of soil microbiota, this research contributes to global efforts to mitigate the antibiotic crisis and advance the discovery of novel antimicrobial agents.
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