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( Pei-pei Han ),( Wen-ji Geng ),( Meng-nan Li ),( Shi-ru Jia ),( Ji-long Yin ),( Run-ze Xue ) 한국미생물 · 생명공학회 2021 Journal of microbiology and biotechnology Vol.31 No.9
Microbially induced calcium carbonate precipitation (MICP) has recently become an intelligent and environmentally friendly method for repairing cracks in concrete. To improve on this ability of microbial materials concrete repair, we applied random mutagenesis and optimization of mineralization conditions to improve the quantity and crystal form of microbially precipitated calcium carbonate. Sporosarcina pasteurii ATCC 11859 was used as the starting strain to obtain the mutant with high urease activity by atmospheric and room temperature plasma (ARTP) mutagenesis. Next, we investigated the optimal biomineralization conditions and precipitation crystal form using Plackett-Burman experimental design and response surface methodology (RSM). Biomineralization with 0.73 mol/l calcium chloride, 45 g/l urea, reaction temperature of 45°C, and reaction time of 22 h, significantly increased the amount of precipitated calcium carbonate, which was deposited in the form of calcite crystals. Finally, the repair of concrete using the optimized biomineralization process was evaluated. A comparison of water absorption and adhesion of concrete specimens before and after repairs showed that concrete cracks and surface defects could be efficiently repaired. This study provides a new method to engineer biocementing material for concrete repair.
Characterization of proteolysis in muscle tissues of sea cucumber Stichopus japonicus
Chen-Chen Zhao,Yang Yang,Hai-tao Wu,Zhi-Mo Zhu,Yue Tang,Cui-Ping Yu,Na Sun,Qiang Lv,Jia-Run Han,Ao-Ting Li,Jia-Nan Yan,Yue Cha 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.6
The proteolysis in muscle tissues of sea cucumber Stichopus japonicus (sjMTs) was characterized. The proteins from sjMTs were primarily myosin heavy chains (MHCs), paramyosin (Pm), and actin (Ac) having a molecular mass of approximately 200, 98, and 42 kDa, respectively. Based on SDS-PAGE analysis and quantification of trichloroacetic acid (TCA)-soluble peptides released, degradation of muscle proteins from sjMTs was favorable at pH 5 and 50°C. Proteolysis of MHCs was mostly inhibited by cysteine protease inhibitors, including trans-epoxysuccinyl-L-leucyl-amido (4- guanidino) butane (E-64) and antipain (AP). E-64 and AP completely inhibited the degradation of Pm and Ac, while iodoacetic acid showed a partially inhibitory effect. These results indicated that the proteolysis of sjMTs was mainly attributed to cysteine proteases. Avoidance of setting the tissues at 40–50oC and slightly acidic condition and inhibition of cysteine proteases are helpful for decreasing sea cucumber autolysis.