Inhibitory effects of some metal complexes on four culturable bacteria isolated from indoor air of 30 Unilorin offices

Abstract

Abstract Microbial contamination indoors significantly impacts air quality and human health. This study focused on microbial contamination in indoor environments, specifically in 30 offices at the University of Ilorin. The research aimed to isolate, characterize, and identify bacteria present in the indoor air. Additionally, the antibiotic sensitivity of the isolated bacteria to four metal complexes was examined. Two offices were sampled in each of the fifteen faculties using the settling plate technique over a five-week period. The bacterial colonies were counted, expressed in cfu m-3, and purified for identification using molecular tools based on 16S rRNA. Four metal complexes (Co(suf)AMZ, Mn(suf)AMZ, Cu(suf)AMZ, and Ni(suf)AMZ) were tested for antibiotic sensitivity using the agar well diffusion method. The study found three Bacillus species and one Pseudomonas species among the isolated bacteria. Bacillus pumilus was consistently present in all offices throughout the entire sampling period. Pseudomonas sp. and Bacillus subtilis appeared in all offices sampled in the fifth week. The total bacterial count ranged from 215 cfu m-3 to 11,164 cfu m-3. Metal complexes Co(suf)AMZ and Ni(suf)AMZ did not inhibit Bacillus altitudinis, while Ni(suf)AMZ, Mn(suf)AMZ, and Cu(suf)AMZ inhibited the growth of Bacillus pumilus. The environmental conditions of the offices showed a maximum temperature of 36.0 oC, a minimum of 27.1 oC, a maximum relative humidity of 54±3.5 %, and a minimum of 30±0.7 %. The study recommends proper sanitation in offices to reduce the risk of opportunistic infections associated with the identified bacteria and enhancement of the complexes used.