Microbiological contamination of lettuce (Lactuca sativa) reared with tilapia in aquaponic systems and use of bacillus strains as probiotics to prevent diseases: A systematic review

by Angélica Adiação Jossefa, Leonildo dos Anjo Viagem, Brunno da Silva Cerozi, Sebastian Wilson Chenyambuga

Aquaponic systems are food production systems that combine aquaculture and hydroponic in a closed recirculation system where water provides nutrients to plants while plants purify water for fish. In this system, tilapia is the most commonly cultured fish and can be easily integrated with vegetable cultivation. However, tilapia host a diverse microbiota some of which are pathogenic and can infect humans. Previous studies have reported contamination of lettuce by pathogenic bacteria which can cause human diseases. Thus, there is an urgent need to employ effective methods to control those bacteria, and Bacillus strains have been successfully used in this context. This systematic review aimed to provide a comprehensive overview of lettuce contamination by pathogenic bacteria and the use of Bacillus as probiotics to prevent diseases in aquaponics systems. This systematic review was performed using Preferred Reporting Items for Systematic Review and Meta-Analysis Statement (PRISMA) Guidelines. A total of 1,239 articles were retrieved and based on eligibility criteria, six articles were included after screening. The review revealed that Enterobacteriaceae, Coliforms, and Shiga Toxin-producing E. coli are the predominant bacteria contaminating lettuce leaves in Aquaponic systems, and Shiga Toxin-Producing E. coli can internalize in the lettuce leaves, putting public health at risk. The included studies did not report the presence of V. cholerae in lettuce grown in aquaponic systems, and the use of Bacillus as probiotics to control Escherichia coli and Vibrio Cholerae. Further research is needed to explore the potential of tilapia to act as a source of pathogenic bacteria that can contaminate lettuce, as well as to investigate the effectiveness of Bacillus strains as probiotics to control these bacteria and ensure food safety.