Identification and Characterization of a Novel Bacterial Species Found in the Lebanese Soil

Abstract

The disruption of the soil's ecosystem causes a disturbance in microbial communities and leads to the emergence of dangerous resistant pathogens and most antibiotic resistance genes. An unknown bacterial strain was collected from a mushroom compost in the Lebanese soil as part of another project aiming to identify bacteria capable of being used in bio-cementation. Our study aims to identify and characterize the unknown strain, its features, behavior, and infectious potential. Standardized techniques were used to determine the morphology and staining properties of the bacteria, biochemical and physiological reactions, and susceptibility and resistance to different antimicrobial agents. Since the strain originated from a mushroom compost in the soil, potassium hydroxide ruled out fungal entities. The bacteria are Gram-negative, rod-shaped, obligate aerobes, non-spore forming and non-encapsulated, urease, coagulase, and catalase-positive, oxidase-negative, possessing β-hemolytic activity, and resistant to UV light. The bacterial strain did not form biofilms at the air liquid interface and produced calcium carbonate precipitates. Antimicrobial susceptibility tests were carried out using antibiotics of major classes and Cannabidiol (CBD) oil. The strain conferred resistance to azithromycin, doxycycline, and trimethoprim-sulfamethoxazole. CBD demonstrated bactericidal activity at low doses but did not have an effect at higher concentrations. Based on the results obtained, we determined that the strain belonged to the genus Gluconacetobacter. All in all, these findings provide preliminary results related to the potential virulence of the bacterial species and its resistance to different antimicrobials. Future in vivo studies are required to determine the infectivity spectrum of the bacteria. Whole genome sequencing is also essential to detect and analyze resistance genes, virulence factors, and clusters for the production of bio-cement.