Temporal Variations in the Biofilm Formation Ability of Vibrio sp. Isolated from Giant Freshwater Prawn (Macrobrachium rosenbergii)

Abstract

The formation of biofilms by Vibrio-like pathogens is a crucial adaptation that enhances their virulence and survival in harsh conditions. Due to the pronounced resistance exhibited by biofilm bacteria, it is crucial to assess these aspects to implement effective mitigation and preventive measures. The present study examines the temporal variation of biofilm formation by Vibrio spp. isolated from Macrobrachium rosenbergii. The Vibrios used for the study were isolated from M. rosenbergii captured from Sri Lankan reservoirs located in the Hambanthota and Monaragala districts. Ninety-six well microtiter plates were used to determine the biofilm-forming ability of isolated Vibrios at 24 hrs, 48 hrs, 72 hrs, 96 hrs, and 120 hrs post incubation times at room temperature. Following the investigation, the isolates were classified into four categories: Non-Biofilm Formers (NBF), Weak Biofilm Formers (WBF), Moderate Biofilm Formers (MBF), and Strong Biofilm Formers (SBF). Fourteen colonies (41.18%) among thirty-four tested had a perpetual ability to biofilms (nine WBF, four MBF, and one NBF) whilst another thirteen (38.24%) showed an increasing ability in which seven were WBF initially and then became MBF. Three isolates showed no biofilm formation (NBF) at 24 hours post-incubation, and with time, they developed WBF. The other three isolates were WBF at 24 hours, MBF at 48, 72, and 96 hours, and SBF at 120 hours. Of the tested thirty-four colonies, only four colonies showed increasing biofilm-forming ability followed by a declining ability (WBF-24 hrs, MBF-48 & 72 hrs, and WBF-96 & 120 hrs). The remaining three isolates were MBF at 24 hours post incubation and NBF at four other incubation periods. Investigated Vibrio sp. showed varying flairs of biofilm formation abilities. These biofilm bacteria, capable of withstanding discrete stress conditions and various host defensive mechanisms and should be properly controlled to mitigate their risk.