Sanitization of hydroponic farming facilities in Singapore: what, why, and how

• Published in: Applied and environmental microbiology 2024-07, Vol.90 (7), p.e0067224
• Main Authors: Tham, Cliff An Ting, Zwe, Ye Htut, Ten, Michelle Mei Zhen, Ng, Geraldine Shang Ya, Toh, Jillinda Yi Ling, Poh, Bee Ling, Zhou, Weibiao, Li, Dan
• Format: Article
• Language: English
• Subjects: Applied and Industrial Microbiology; Bacteria - classification; Bacteria - drug effects; Bacteria - isolation & purification; Biofilms - drug effects; Biofilms - growth & development; Disinfectants - pharmacology; Disinfection - methods; Farms; Food Microbiology; Hydrogen Peroxide - pharmacology; Hydroponics; Salmonella typhimurium - drug effects; Salmonella typhimurium - growth & development; Salmonella typhimurium - physiology; Singapore; Sodium Hypochlorite - pharmacology
• ISSN: 0099-2240; 1098-5336; 1098-5336
• DOI: 10.1128/aem.00672-24

This study performed microbial analysis of nutrient film technique (NFT) hydroponic systems on three indoor farms in Singapore (the "what"). To justify the necessity of sanitizing hydroponic systems, strong biofilm-forming bacteria were isolated from the facility and investigated for their influence on colonization on polyvinyl chloride (PVC) coupons in hydroponic nutrient solutions (the "why"). Finally, sanitization solutions were evaluated with both laboratory-scale and field-scale tests (the "how"). As a result, the microbiome composition in NFT systems was found to be highly farm specific. The strong biofilm formers C2 and C3 were found to facilitate the attachment and colonization of on PVC coupons. When forming dual-species biofilms, the presence of C2 and C3 also significantly promoted the growth of ( < 0.05). Compared with hydrogen peroxide (H O ) and sodium percarbonate (SPC), sodium hypochlorite (NaOCl) exhibited superior efficacy in biofilm removal. At 50 ppm, NaOCl reduced the Typhimurium, C2, and C3 counts to