With four Pleurotus eryng# varieties as test materials, the mycelium pelletdensity, dry weight and diameter, fermentation broth pH value, and deoxidized sugar content were determined during their liquid fermentation to investigate the growth of mycelia and changes in fermentation broth. In addition, the sensory, biochemical and microbiological indicators of excellent P. eryngii mycelia were determined by sensory tests, microscope morphology observation and mycelium pellet back-inoculation tests. The results showed that the standards for high-quality liquid spawn of P. eryngii were as follows： bacterial liquid was light yellow and clarifiedwith rich bitter almond flavor but no bacterial contamination; mycelium pellets were visible, white and uniform with burrs on the surface, diameter 〈2.5 mm and concentration of 80%-100%; mycelium pellets were stout, and there were 3--4 clamp connectionsper visual field under the microscope; fermentation time was generally 120-144 h.
[目的]以甲醛降解菌宛氏拟青霉菌F1-23为实验菌株,分离纯化得到甲醛脱氢酶的酶液,并考察其酶学性质。[方法]从液体培养液中收集菌体,通过细胞粉碎,采用(NH4)2SO4沉淀、透析、DFAE-Sepharose离子交换层析及Superdex-200凝胶过滤层析,纯化得到电泳纯的FADH。[结果]该酶的分子量约为112.81 k Da;亚基分子量分别为65k Da和42 k Da;纯酶液活力为336.10 U/mg,较纯化前提高了4.02倍。对该酶的酶学性质分析结果表明,该酶最适反应温度为37℃,在25~45℃时稳定性很好;最适反应p H为8.0,在p H 6.5~8.0范围内酶活力较为稳定。底物特异性研究表明FADH最适底物为甲醛,相对偏好短链醛类。金属离子对酶活性的影响试验表明,Zn^(2+)、Mn^(2+)、Ag^+、Fe^(3+)和Hg^(2+)几乎完全抑制FADH酶活力;Ca^(2+)对酶活有促进作用。纯酶液在4℃环境下,在24h内可保存78%的活性。[结论]FADH结构较为特殊,且活性较大,为后期表达和深入研究其生物学功能提供理论和数据支持。
分离研究家酿葡萄汁饮品中的优势酵母菌,为本地葡萄酿酒酵母资源的筛选及其利用奠定基础。从家酿葡萄汁饮品中分离得到一株优势酵母菌(命名为CSLG02),结合显微结构和生理生化试验结果,以及对其26S r DNA D1/D2序列的分析确定该菌株的系统发育地位;通过人为地在葡萄汁中添加试验菌株CSLG02,发酵酿制葡萄汁饮品,考察饮品的各个理化指标。研究结果表明,菌株CSLG02鉴定为酿酒酵母属(Saccharomyces cerevisiae)。添加该菌后的试验组较对照组,饮品中各个理化指标均有不同程度的改变。S.cerevisiae CSLG02的添加,能改善家酿葡萄汁饮品的口感和品质,对形成地域性葡萄汁饮品的研究具有实际帮助意义。
