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Lactobacillus paracasei (L. paracasei), a common probiotic lactobacillus, has important functions in the food industry and human health. However, different strains of L. paracasei inevitably show differences in activity and colonization resistance, leading to differentiation in their functions, as well as their physical or chemical properties. The purpose of this study was to evaluate the characteristics of L. paracasei R3 (L.p R3) isolated from healthy human feces and determine whether the criteria for edible probiotics is met. The hemolysis type, biofilm-forming ability, antibiotic susceptibility, toxicity, and effective activity of L.p R3 were determined by establishing its probiotic activity traits in vitro and in vivo. The results showed that L.p R3 had a moderate biofilm formation ability, was sensitive to 11 antibiotics, was resistant to eight antibiotics, and was not hemolytic. The culture characteristics, morphology, and biochemical responses of the strain were consistent with the seed batch characteristics. In toxicity assays, L.p R3-fed mice showed no abnormalities in body weight, growth, or various organs. Additionally, L.p R3 was found to be effective in the prevention and treatment of colorectal cancer. In conclusion, our results revealed that L.p R3 has potential value as an edible probiotic without toxic side effects and alleviated the tumor progression of colorectal cancer in mice. [ABSTRACT FROM AUTHOR]

E. coli L-asparaginase, an antitumor enzyme, was chemically modified with N, O-carboxymethyl chitosan to lower its antigenicity and increase its plasma half-life. The results showed that the modified L-asparaginase has almost the same apparent Km value as that of native enzyme. The modified L-asparaginase also showed a higher protease stability against trypsin and α-chymotrypsin. After being modified, the enzyme exhibited the complete loss of antigenicity towards antiasparaginase serum. In addition, the higher the molecular weight of modifying reagents, the better the effects on reduction of antigenicity. When tested in vivo, the plasma half-life of the modified enzyme ( t 1/2 = 40 h) was over 33 times longer than that of the native enzyme ( t 1/2 = 1.2 h) [ABSTRACT FROM AUTHOR]