The Characteristic Properties of Wheat Flour Dough with New Leavening Bacteria

1.发酵菌阴沟肠杆菌GAO(以下简称GAO)在含有葡萄糖和天冬酰胺的G-培养基中培养时产生H_2和CO_2气体。当添加0.1%的酪氨酸时，产气量增加约2.5倍，H_2/CO_2比为0.60.2。在添加0.5%柠檬酸、0.5%α-酮戊二酸、0.5%琥珀酸、延胡索酸、苹果酸和丙酮酸的G-GAO培养基中，产生H_2气体是GAO生长的主要原因。GAO产生的总气体由高到低依次为富马酸、丙酮酸、α-酮戊二酸、柠檬酸、苹果酸和琥珀酸。氢气占总气的比例为：α-酮戊二酸85.1%，柠檬酸82.1%，琥珀酸81.5%。通过硫酸铵分级沉淀、Sephacryl S-200凝胶过滤、DEAE-TOYOPERL柱层析、1-硫代-β-半乳糖苷-琼脂糖亲和层析、Mono-Q柱层析等步骤，从赤霉菌细胞提取液中分离纯化出2-β-半乳糖苷。酶制剂在聚丙烯酰胺凝胶上均一。该酶的最适pH为7.2，最适温度为37ﾟC，在37ﾟC下孵育30min，酶的相对分子质量稳定在pH 6.0~7.0之间。这表明该酶可能由2个亚基组成。酶的等电点为pH 4.5。当测定浓度为1 mM时，含镁、锌、锰、钴、镍的二价金属为强激活剂。阴沟肠杆菌GAO产β-半乳糖苷酶的甘氨酸和丝氨酸含量高于阴沟气杆菌。从马铃薯填充剂制备的发酵剂中分离得到4株细菌，分别为杆状、加氧酶阳性和革兰氏阴性菌。

1. The leavening bacterium Enterobacter cloacae GAO (hereafter referred to as GAO) produced H_2 and CO_2 gas when the GAO was cultured with G-medium which contained glucose and asparagine. The amount of gas increased adding at 0.1% casaminoacid for G-medium produced roughly 2.5-fold and H_2/CO_2 ratio was 0.60.2. The formation of H_2 gas was accounted for the GAO growth with 0.1% casaminoacid G-media supplemented with 0.5% citric acid, alhpa -ketoglutaric acid, succinic acid, fumaric acid, malic acid and pyruvic acid respectively. The GAO produced total gas, in order of its abundace, fumaric acid, pyruvic acid, alpha -ketoglutaric acid, citric acid, malic acid and succinic acid. The ratio of H_2 to total gas were showen that alpha -ketoglutaric aicd was 85.1%, citric acid was 82.1% and succinic acid was 81.5%.3. Two- beta -galactosidaese were purified from the cell extract of the GAO by ammonium sulfate fractionation, Sephacryl S-200 gel filtration, DEAE-Toyopearl column chromatography, affinity chromatography on 1-thio- beta -galactopyranoside-Agarose and mono-Q column chromatography. The enzuyme preparations homogeneous on polyacrylamide electrophresis. The enzyme was most active at pH 7.2 and 37^ﾟ C. The enzyme was stable between pH 6.0 to 7.0 at 30 min incubation at 37^ﾟ C. The molecular weights of the enzyme was estimated to be 220,000 by gel filtration on Sepharose CL-6B column, and 120,000 by SDS polyacrylamide gelelectrophoresis. This indicated that the enzymes might be of 2 subunits. The isoelectric point of the enzymes was pH 4.5. Bivalent metals with Mg, Zn, Mn, Co, Ni are strong activators when assayed at 1mM concentration. The beta -galactosidase from E. Cloacae GAO had high content of glycine and serine compared with Aerobacter cloacae.4. In an attempt to isolation from the starter prepared with potato filling, we obtained four isolates which were rod shape, oxydase positive and Gram negative bacteria.