Evaluating the Impact of Bacillus subtilis on Salmonella Biofilm Formation: A Co-Culture Study
T. D. Induwara
Belarusian State medical University, Minsk, Dzerzhinsky Ave., 83 220083, Republic of Belarus.
D. N. N. Madushanka
Department of Livestock Production, Faculty of Agricultural Sciences, Sabaragamuwa University of Sri Lanka, Belihuloya, Sri Lanka.
T. S. P. Jayaweera
Department of Livestock Production, Faculty of Agricultural Sciences, Sabaragamuwa University of Sri Lanka, Belihuloya, Sri Lanka.
H. A. D. Ruwandeepika *
Department of Livestock Production, Faculty of Agricultural Sciences, Sabaragamuwa University of Sri Lanka, Belihuloya, Sri Lanka.
*Author to whom correspondence should be addressed.
Abstract
Background: Biofilms are structured bacterial communities that enhance microbial survival and significantly contribute to persistent, antibiotic-resistant infections in clinical settings.
Aims: This study aimed at investigating the interaction between Salmonella spp. and Bacillus subtilis (ATCC 6633) during biofilm formation and assessing the potential antagonistic effects of B. subtilis in co-culture systems.
Study Design: Quantitative and qualitative analysis of biofilms formed by Salmonella isolates in mono- and dual-species cultures with B. subtilis In vitro.
Place and Duration of Study: The study was conducted at the Livestock Laboratory, Department of Livestock Production, Faculty of Agricultural Sciences, Sabaragamuwa University of Sri Lanka.
Methodology: Ten Salmonella isolates obtained from the laboratory repository maintained at -800 C were cultured as mono and dual-species biofilms with B. subtilis in 96 wells micro titer plates. Quantification of the biofilm formation was done by using a microtiter plate assay according to the standard protocol. As a qualitative assay, the fluorescence microscopy was used to visualize cellulose components in the biofilm matrices following the Calcofluor white staining procedure.
Results: Eight out of ten (8/10) Salmonella isolates exhibited a significant reduction (P < 0.05) in biofilm formation when co-cultured with B. subtilis, with reductions ranging from 21.6% to 64.9%. Fluorescence microscopy confirmed disrupted biofilm architecture and reduced cellulose content in dual-species biofilms compared to the mono species biofilm. Two isolates showed no significant reduction in biofilm formation when co cultured.
Keywords: Salmonella, Bacillus subtilis, biofilm formation, biofilm inhibition, co-culture interaction, fluorescence microscopy, antagonistic activity