Electrochemical In Situ Hydrogen Peroxide Production Can Reduce Microbial Load in Bioponic Nutrient Solutions Derived from Organic Waste

Kriem, Lukas Simon; Pietzka, Carsten; Beckett, Marc; Gärtling, Luisa; Wriedt, Benjamin

doi:10.3390/agriculture13112122

Cited by 2 publications

References 40 publications

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Microbial Analysis and Sanitization of Hydroponic Farming Facilities in Singapore

Tham,

Zwe,

Ten

et al. 2024

Preprint

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This study performed microbial analysis of nutrient film technique (NFT) hydroponic systems at three indoor farms in Singapore. To justify the necessity to sanitize the hydroponic systems, strong biofilm-forming bacteria were isolated from the facility and investigated with their influence onSalmonellacolonizing on polyvinyl chloride (PVC) coupons in hydroponic nutrient solutions. Last, sanitization solutions were evaluated with both laboratory-scale and field-scale tests. As a result, the microbiome composition in NFT systems was found to be highly farm-specific. Strong biofilm formersCorynebacterium tuberculostearicumC2 andPseudoxanthomonas mexicanaC3 were found to facilitate the attachment and colonization ofSalmonellaon PVC coupons. When forming dual-species biofilms, the presence of C2 and C3 also significantly promoted the growth ofSalmonella(P< 0.05). Sodium hypochlorite (NaOCl) exhibited superior efficacy in biofilm removal compared to hydrogen peroxide (H2O2) and sodium percarbonate (SPC). NaOCl at 50 ppm reduced C2 and C3 counts to < 1 log CFU/cm2within 12 h, whereas neither 3% H2O2nor 1% SPC achieved such an effect. In operational hydroponic systems, the concentration of NaOCl needed to achieve biofilm elimination increased to 500 ppm, likely due to the presence of organic matter accumulated during the crop cultivation and the higher persistence of the naturally formed multispecies biofilms. The sanitization (500 ppm NaOCl for 12 h) did not impede subsequent plant growth but chlorination by-product chlorate was detected with high levels from the hydroponic solution and plants in the sanitized systems without rinsing.IMPORTANCEThis study’s significance lies first in its elucidation of the necessity to sanitize the hydroponic farming systems. The microbiome in hydroponic systems, although most of the times non-pathogenic, might serve as a hotbed for pathogens’ colonization and thus pose a higher risk for food safety. We thus explored sanitization solutions with both laboratory-scale and field-scale tests. Of the three tested sanitizers, NaOCl was the most effective and economical option, whereas one must note the vital importance of rinsing the hydroponic systems after sanitization with NaOCl.

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Microbial Analysis and Sanitization of Hydroponic Farming Facilities in Singapore

Tham,

Zwe,

Ten

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

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

Tham,

Zwe,

Ten

et al. 2024

Appl Environ Microbiol

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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 Salmonella 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 Corynebacterium tuberculostearicum C2 and Pseudoxanthomonas mexicana C3 were found to facilitate the attachment and colonization of Salmonella on PVC coupons. When forming dual-species biofilms, the presence of C2 and C3 also significantly promoted the growth of Salmonella ( P < 0.05). Compared with hydrogen peroxide (H 2 O 2 ) and sodium percarbonate (SPC), sodium hypochlorite (NaOCl) exhibited superior efficacy in biofilm removal. At 50 ppm, NaOCl reduced the Salmonella Typhimurium, C2, and C3 counts to <1 log CFU/cm 2 within 12 h, whereas neither 3% H 2 O 2 nor 1% SPC achieved this effect. In operational hydroponic systems, the concentration of NaOCl needed to achieve biofilm elimination increased to 500 ppm, likely due to the presence of organic matter accumulated during crop cultivation and the greater persistence of naturally formed multispecies biofilms. Sanitization using 500 ppm NaOCl for 12 h did not impede subsequent plant growth, but chlorination byproduct chlorate was detected at high levels in the hydroponic solution and in plants in the sanitized systems without rinsing. IMPORTANCE This study’s significance lies first in its elucidation of the necessity of sanitizing hydroponic farming systems. The microbiome in hydroponic systems, although mostly nonpathogenic, might serve as a hotbed for pathogen colonization and thus pose a risk for food safety. We thus explored sanitization solutions with both laboratory-scale and field-scale tests. Of the three tested sanitizers, NaOCl was the most effective and economical option, whereas one must note the vital importance of rinsing the hydroponic systems after sanitization with NaOCl.

show abstract

Electrochemical In Situ Hydrogen Peroxide Production Can Reduce Microbial Load in Bioponic Nutrient Solutions Derived from Organic Waste

Cited by 2 publications

References 40 publications

Microbial Analysis and Sanitization of Hydroponic Farming Facilities in Singapore

Microbial Analysis and Sanitization of Hydroponic Farming Facilities in Singapore

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

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