en تخصصي Special مقاله اصیل Original Article <div style="text-align: justify;">Introduction: The increasing population, water scarcity, and resource limitations challenge sanitation management, especially in developing countries. Traditional wastewater treatments, like flush toilets and chemically treated portable toilets, have drawbacks such as high energy consumption and odor issues. Lactic acid fermentation using Lactobacillus spp. presents a costeffective, sustainable alternative by lowering pH and inhibiting pathogens. This study evaluated the effect of Lactobacillus casei fermentation on simulated fecal matter for potential use in fishing vessels, rural areas, and resource-limited settings.<br> Methods: L. casei exhibited exponential growth up to 8 hours before stabilizing, with reduced proliferation at ambient temperature. Simulated fecal matter was prepared with microcrystalline cellulose, psyllium husk, oleic acid, mineral salts, soybean flour, and 15% molasses to enhance lactic acid production. Experiments were conducted using simulated feces compared to human feces, evaluating pH, microbial concentration, and physicochemical parameters.<br> Results: Fermentation with L. casei (10% and 20%) reduced pH to approximately 4.0 within six days, remaining stable until day 30. Lactic acid production followed a similar trend, while Escherichia coli concentrations (initially 2.55 &times; 107 CFU/g) significantly decreased, with maximum reduction by day six. Comparable effectiveness between 10% and 20% L. casei suggests reduced inoculum concentrations may suffice for microbial control.<br> Conclusion: These findings support L. casei fermentation as a promising biotechnological approach for pathogen reduction in waste treatment. The potential application of this method in portable sanitation systems, especially in rural areas with limited resources, is highlighted, contributing to sustainable waste management and pathogen control.</div> Lactobacillus casei, Escherichia coli, Lactic acid fermentation, Fecal matter 1 8 http://ehemj.com/browse.php?a_code=A-10-1-458&slc_lang=en&sid=1 Yohiss del Rocío Medina-Chávez yohissdelrocio@gmail.com 100319475328460022405 0009-0006-6215-4226 No Laboratorio de Calidad de Aguas y Medio Ambiente de la Universidad Tecnológica del Perú, Av. Tacna y Arica 160, 04001 Arequipa, Perú Daniela Camacho-Valencia C26618@utp.edu.pe 100319475328460022406 100319475328460022406 No Laboratorio de Calidad de Aguas y Medio Ambiente de la Universidad Tecnológica del Perú, Av. Tacna y Arica 160, 04001 Arequipa, Perú José Antonio Villanueva-Salas jvillans@ucsm.edu.pe 100319475328460022407 100319475328460022407 No Universidad Católica de Santa María, Urb. San José s/n Umacollo, 04001 Arequipa, Perú Stamber Alvaro Ramírez-Revilla sramirezr@utp.edu.pe 100319475328460022408 100319475328460022408 Yes Correspondence to: Laboratorio de Calidad de Aguas y Medio Ambiente de la Universidad Tecnológica del Perú, Av. Tacna y Arica 160, 04001 Arequipa, Perú