No abstract

Clostridium perfringens is a gram-positive, anaerobic, spore-forming bacterium capable of producing four major toxins which cause disease symptoms and pathogenesis in humans and animals. C. perfringens strains carrying enterotoxins can cause food poisoning in humans and are associated with meat consumption. An endolysin, named LysCP28, is encoded by orf28 from C. perfringens bacteriophage BG3P. This protein has an N-terminal glycosyl–hydrolase domain (lysozyme) and a C-terminal SH3 domain. Purified LysCP28 (38.8 kDa) exhibited a broad spectrum of lytic activity against C. perfringens strains (77 of 96 or 80.21%), including A, B, C, and D types, isolated from different sources. Moreover, LysCP28 (10 μg/mL) showed high antimicrobial activity and was able to lyse 2 × 107 CFU/mL C. perfringens ATCC 13124 and C. perfringens J21 (animal origin) within 2 h. Necessary due to this pathogenic bacterium’s ability to form biofilms, LysCP28 (18.7 μg/mL) was successfully evaluated as an antibiofilm agent in both biofilm removal and formation inhibition. Finally, to confirm the efficacy of LysCP28 in a food matrix, duck meat was contaminated with C. perfringens and treated with endolysin (100 µg/mL and 50 µg/mL), which reduced viable bacteria by 3.2 and 3.08 units-log, respectively, in 48 h at 4 °C. Overall, the endolysin LysCP28 could potentially be used as a biopreservative to reduce C. perfringens contamination during food processing.

Abstract

Copper hydroxyphosphate,as self-assembled nanoparticles, was synthesized by using a hydrothermal method,with cupric acetate (Cu(CH3COO)2·H2O) and diammonium hydrogen phosphate ((NH4)2HPO4) as raw materials. Physical property of copper hydrophosphate was characterized by X-ray diffraction (XRD), Field-emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and Ultraviolet obvious diffuse reflection(UV-vis DRS). No surfactants or templates were added in the procedure of preparation. By simply adjusting the pH from 3 to 9, the morphology of copper hydrophosphate varied from microrods to walnutshaped microspheres. Photocatalytic activity of the samples was also investigated. Photo decoloration of Rhodamine B in water under visible light irradiation shows that copper hydrophosphate (pH=7) have the best photocatalytic activity: Photodecoloration activity of 100 mL Rhodamine B (10 mg/L) was 98 % under illumination for 30 min.