Immobilization of Providencia stuartii Cells in Pumice Stone and Its Application for N-Acetylglucosamine Production

RESEARCH BACKGROUND: Shrimp shells contain chitin that can be further processed into N-acetylglucosamine, which has been extensively used to treat joint damage. Providencia stuartii has a strong chitinolytic activity and may be utilized in the form of immobilized cells in repeated fermentation. Pumice is a porous and rigid stone that offers superior mechanical strength, making it suitable for immobilization. EXPERIMENTAL APPROACH: In the research submerged fermentation with different pumice stone sizes and pumice stone/growth medium ratios (m/V) was carried out for 4 days at 37 °C and pH=7.0. The optimum pumice stone size and pumice stone/growth medium ratio (m/V) were used to determine the optimum fermentation cycle for the production of N-acetylglucosamine using immobilized P. stuartii. RESULTS AND CONCLUSIONS: Pumice stones of 1.0 cm×1.0 cm×1.0 cm and pumice stone/growth medium ratio of 1:5 were found to be the optimum conditions for successful immobilization of (90.0±1.6) % cells and production of (331.4±7.3) g/L N-acetylglucosamine. The highest N-acetylglucosamine concentration of (323.0±2.5) g/L was obtained in the first fermentation cycle, which then decreased and remained stable throughout the last three cycles. NOVELTY AND SCIENTIFIC CONTRIBUTION: P. stuartii, a strong chitinolytic bacterium previously isolated from rotten shrimp shells, was used for the first time in immobilized form to produce N-acetylglucosamine. The findings in this research showed the potential use of P. stuartii cells immobilized in pumice stone for continuous production of N-acetylglucosamine in repeated fermentation.