The Microbial World: Control of Microbial Growth

Abstract

This report details the results of four experiments that investigated the effect of physical and chemical techniques on the control of microbial growth, which have been carried out through three laboratory sessions in BIO60002 at Islamia University of Bahawalpur Pakistan. In the first set of experiments (Part 1), moist-heat sterilisation by autoclave, the antimicrobial activity of six disinfectants and antiseptics against Bacillus subtilis, antibiotic sensitivity profile of Staphylococcus epidermidis and Escherichia coli and the Minimum Inhibitory Concentration (MIC) of phenol on E. coli were evaluated. In the second set (Part 2), the bactericidal effects of moist heat (60°C) and Ultraviolet (UV) irradiation was evaluated against B. subtilis and then class-wise results were compared with four species. B. subtilis endospores were eliminated in both packing conditions in the autoclave. The efficacy of the disinfectants also differed, with White King and Tea Tree Oil having the widest zone of inhibition. The MIC of phenol was found as 1:200. The results of the UV treatment were very effective, destroying all colonies of B. subtilis within 40 seconds, while the thermoresistance of endospores is well known, and they did not always reduce colony counts at 60°C.

Keywords: Chemical Techniques; Microbial Activities; Disinfectants

Citation

Asghar A, Ali H. The Microbial World: Control of Microbial Growth. WebLog J Microbiol. wjm.2026.i1801. https://doi.org/10.5281/zenodo.23103418