200: Genetic Determinants Related to Persistence of Environmental Microflora in Dairy Processing Environments

Introduction

Cross-contamination from the processing environment can compromise food safety. In dairy processing facilities, microorganisms persist in the environment due to their ability to form biofilms. By studying the genomic makeup of microbial communities, we can uncover the genetic factors that drive biofilm formation. This study examines the biofilm-associated genetic components in microflora from air and floor swab samples of dairy processing environments to assess their persistence.

Methods

Floor swab samples were collected from five adjacent sites along each of the five processing lines, and air samples were taken from the same lines using an air sampler and aerobic plate count (APC) strips. Swabs were plated on the Tryptic soy agar (TSA) plates and incubated at 37⁰C/24-48h. Distinct colonies from the APC strips and TSA plates having different colony morphology were grown individually in Tryptic soy broth. Genomic DNA was extracted from the individual isolates using the Wizard Genomic DNA extraction kit and subjected to whole-genome sequencing with the PromethION nanopore sequencer. After genome assembly, annotations were generated using the RAST server to identify genes and metabolic subsystems related to biofilm formation. Species identification was conducted using the Type strain genome server.

Results

A total of 22 isolates were sequenced, revealing variations in the microflora between air and floor swab samples. Pseudomonas (14%) and Klebsiella (10%) spp. were most prevalent in swab samples, while Bacillus spp. (10%) was most prevalent in air samples. Genes associated with key biofilm-related functions were identified across all isolates, including those related to adhesion, membrane transport, regulation, detoxification, capsular, extracellular polysaccharide, and cell signaling, which were more prevalent in swab samples, while dormancy and sporulation genes were more prevalent in air isolates. The abundance of biofilm-associated genes in swab isolates suggests a higher risk of long-term persistence and cross-contamination, while air microflora exhibits genes favoring short-term persistence.

Significance

Identification of genetic determinants of the environmental microflora associated with biofilm formation provides valuable insights into the mechanisms driving the persistence in dairy processing facilities. Understanding these genetic components can help in developing effective strategies to prevent biofilm formation and improve food safety.

Authors: Vaishali Poswal, Sanjeev Anand, J.L. Gonzalez Hernandez, Brian Kraus