EFFECTS OF PROBIOTICS Pedicoccus, Bacillus subtilis AND Lactobacillus acidiophilus ON FOOD SAFETY INDICATORS IN AQUAPONIC SYSTEMS

Fred Gonzales, Jr*, Janelle V Hager, George J. Pate, Zackary W. Perry, James H. Tidwell
Aquaculture Research Center
Kentucky State University
Frankfort, Kentucky 40601
fred.gonzales@kysu.edu

Foodborne pathogens are a source of concern in ready-to-eat foods such as leafy greens. Aquaponic systems combine recirculating aquaculture and soilless vegetable production to produce a wide variety of vegetable produce. Food safety concerns stem from the direct integration of fish culture water with plant grow beds. Typically, pathogens affecting fish are not a risk to human health; however, vectors such as systemic water, birds, mice, and humans may introduce pathogenic organisms. The addition of probiotics into aquaponic system water may competitively exclude pathogenic bacteria by actively altering the composition of microbial communities.

Researchers evaluated the effects of a probiotic mix containing equal parts Pediococcus spp., Bacillus subtilis, and Lactobacillus acidophilus in aquaponic systems. Six, 500 gallon replicate aquaponic systems were each stocked with six kg (~50 fish) of Nile tilapia (Oreochromis niloticus) and 71 Nevada heat tolerant lettuce (Lactuca sativa) plants. Randomized probiotics treatments were inoculated weekly with the probiotic cocktail at a concentration of 106 colony-forming units (CFUs/ml). System water, plant leaves, and plant root samples were collected weekly. Samples were processed, plated onto selective media, and enumerated. Colonies of interest including potential Salmonella spp., Escherichia coli, Enterobacter spp., Vibrio spp., and Listeria monocytogenes were isolated and identified using the bioMérieux Vitek 2 bacterial identification system.

This study was run in two lettuce cycles to reproduce a typical production cycle. A two sample t-test will be used to analyze data between the control and treatment.