Beta hemolytic and beta-lactam antibiotic-resistant strain of Lysinibacillus sphaericus isolated from a tea growing region of West Bengal, India

Abstract. Nandi S, Bhattacharya M. 2025. Beta hemolytic and beta-lactam antibiotic-resistant strain of Lysinibacillus sphaericus isolated from a tea growing region of West Bengal, India. Asian J Trop Biotechnol 22: 1-6. River water and soil are primary sources of bacteria. Some of them often acquire pathogenicity under stressful environmental conditions. Regarding the pathogenicity of a bacterium, hemolysin is the most virulence factor. In this study, 16 isolates possess beta-hemolytic abilities out of 32 isolated copper tolerant bacteria. One of the strains was identified as Lysinibacillus sphaericus (NJCT1) using 16S rRNA sequencing. Lysinibacillus sphaericus is rarely pathogenic in humans but is known for its larvicidal and antagonistic activity in bacteremia-associated infections in immunocompromised patients. Kaljani River basin, the lifeline for the rapidly growing population in the tea-producing region of West Bengal, India, is the source of Gram-positive bacteria used in this study. Due to its pathogenic character, it can create a health problem for the locals if they use the river water frequently. The antibiotic susceptibility study, which involved testing the bacterial strain against a panel of commonly used antibiotics, showed that L. sphaericus (NJCT1) is resistant to 7 antibiotics (colistin, penicillin-g, amoxicillin, ceftazidime, cefuroxime, rifampin, and methicillin). This bacterial strain exhibited resistance against the ?-lactam drug class, whereas complete susceptibility was recorded against drug classes like fluoroquinolones. As the most sensitive drug, fluoroquinolones could solve the problem caused by L. sphaericus isolated from the Kaljani River.