The Characteristic Properties of Wheat Flour Dough with New Leavening Bacteria

1. 发酵细菌阴沟肠杆菌GAO（以下简称GAO）在含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。在g -培养基中添加0.1%的酪胺酸，气体量增加约2.5倍，H_2/CO_2比为0.60.2。在0.1%酪胺酸g -培养基中分别添加0.5%柠檬酸、α -酮戊二酸、琥珀酸、富马酸、苹果酸和丙酮酸，形成H_2气体促进GAO生长。GAO产生的总气体，按其丰度排序为富马酸、丙酮酸、-酮戊二酸、柠檬酸、苹果酸和琥珀酸。H_2与总气的比值表明：α -酮戊二酸为85.1%，柠檬酸为82.1%，琥珀酸为81.5%。采用硫酸铵分离、Sephacryl S-200凝胶过滤、DEAE-Toyopearl柱层析、1-thio- β -半乳糖苷-琼脂糖亲和层析、单q柱层析等方法从高脂多糖细胞提取物中分离纯化2 - β -半乳糖苷。酶制剂经聚丙烯酰胺电泳均相。在pH 7.2和37^ c条件下，酶活性最高。37^ c条件下，酶在pH 6.0 ~ 7.0范围内稳定，经Sepharose CL-6B柱凝胶过滤，酶的分子量为220,000，SDS聚丙烯酰胺凝胶电泳，酶的分子量为120,000。这表明酶可能有2个亚基。酶的等电点pH为4.5。在1mM浓度下，含Mg、Zn、Mn、Co、Ni的二价金属是强活化剂。与厌氧阴沟菌相比，厌氧阴沟菌GAO的β -半乳糖苷酶具有较高的甘氨酸和丝氨酸含量。从马铃薯馅料制成的发酵剂中分离得到棒状菌、氧化酶阳性菌和革兰氏阴性菌4株。

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.