Isolation, characterization and mitigation of biofilm formers for the shelf life extension of farm fresh produce
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Date
2023-03
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CCSHAU, Hisar
Abstract
The present study was conducted to isolate, screen and characterize biofilm forming microorganisms, to compare preservation methods for mitigation of biofilm formers and to evaluate the effect of biofilm retreating methods on the shelf life of farm fresh produce.
Fresh farm produce samples (cabbage, spinach and carrot) were procured to isolate and screen biofilm former. Out of 76 isolates, twenty biofilm former based on their morphological characteristics were selected for further studies. E. coli MTCC249 and S. aureus MTCC133 were taken as control. Biofilm development was confirmed through qualitative tests like Congo red agar, test tube technique, tryptic soy broth test, microtitre plate assay, enzyme activity and scanning electron microscopy. Antibiotic susceptibility and molecular characterization of four isolates (FM1, FM3, FM4 and FM6) forming firm biofilms on the surfaces of cabbage leaves was performed. By BLAST analysis and Seq match databases, four isolates were identified as Bacillus species with accession no. ON849074, ON849074, ON849077 and ON849075 of FM1, FM3, FM4 and FM6, respectively.
To compare the various preservation methods for the mitigation of biofilm former, cabbage leaves were inoculated with isolated and standard cultures. These samples were subjected to a series of treatment applications with independent parameters at different levels like pH, UV light exposure, temperature, salt, peroxyacetic acid, lactic acid and Nisin, respectively. Several combination treatments were created using the Box Behnken, response surface methodology. The combined treatment settings were optimized based on microbial log reduction as the response.
Shelf life studies of cabbage leaves evaluated the effect of treatments showing the maximum inhibition of biofilm formation till spoilage. Physico-chemical attributes viz. moisture, pH, acidity, total sugars, phenolics, carotenoids, pectin, colour and microbial load were studied. Overall, combining Nisin, salt, and UV treatments led to a significant reduction of biofilm former compared to independent treatments. In the future, more research might investigate the cutting-edge fields of predictive microbiology and mathematical modelling to combat biofilm former in the fresh produce industry.