Diversity, biofilm formation and antimicrobial susceptibility of aerobic heterotrophic bacteria isolated from cooling towers.

Authors

Marcus Vinícius Dias-Souza, Andrea Lima Alves, Ubiana de Cássia Mourão Silva, Aline Daniela Lopes Júlio, Andréa Veiga, Sergio Pagnin, Vera Lúcia Dos Santos

Published in

World journal of microbiology & biotechnology. Volume 42. Issue 8. Jul 14, 2026. Epub Jul 14, 2026.

Abstract

Cooling towers (CTw) are essential for industrial refrigeration but provide favourable conditions for microbial growth and biofilm formation, potentially facilitating the spread of antimicrobial-resistant bacteria (ARB). This study examines bacterial diversity, biofilm potential and antimicrobial susceptibility in two industrial CTw in Brazil using culture-based and metataxonomic (16 S rRNA gene amplicon sequencing) approaches. Fourteen bacterial genera and 22 species were identified, including Bacillus spp. (60% of isolates), Acinetobacter spp. (14%) and others like Pseudomonas, Serratia, and Ochrobactrum, many linked to biofilm formation and ARB. Metataxonomic analysis revealed a broader and more diverse microbial community, comprising families such as Burkholderiaceae, Comamonadaceae, and Sphingomonadaceae, which are known for their biofilm resilience. Pathogens including Legionella were also detected. Bacterial richness was higher in CTw 2, likely due to untreated industrial and domestic effluent inputs, whereas CTw 1, supplied with treated secondary industrial effluent, exhibited lower diversity. Functional predictions indicated genes associated with biofilm formation, quorum-sensing, motility and xenobiotic degradation. Antimicrobial susceptibility testing showed high resistance to β-lactams and nitrofurantoin, with meropenem being the most effective. Higher resistance rates in CTw 2 suggest selective pressure from industrial contaminants. These findings underscore the complex microbial ecology of CTw and the coexistence of cultivable and non-cultivable bacteria with biofilm-forming capacity and antimicrobial resistance traits in these systems.

PMID:
42446838
Bibliographic data and abstract were imported from PubMed on 14 Jul 2026.

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