Studies on lactic acid producing bacteria in fermented seafoods

(1)托比岛岛鱼露的化学成分为：氯化钠20.7%，VBN 181 mg/100g，乳酸1,620 mg/100g，谷氨酸1,322 mg/100g，组胺163 mg/100 mg，组胺163 mg/100 mg，组胺163 mg/100 mg。即使在20%(w/v)的NaC l中也不能阻止组胺的形成。(3)首次从四球菌中分离纯化了一种组氨酸脱羧酶。纯酶由两条多肽链组成，分子量分别为28.8 kDa和13.4 kDa。这些多肽的N末端氨基酸序列与其他革兰氏阳性细菌组氨酸脱羧酶…的α链和β链高度相关更多。该酶的最适pH为4.5~7.0，最适pH为4.0~7.0。从四球菌染色体DNA的EcoRI片段中克隆了含有组氨酸脱羧酶(HDC)的基因。对该片段进行序列分析，确定了两个开放阅读框(ORF)。第一个开放阅读框(HdcA)编码316个氨基酸残基，编码S，与小鼠血吸虫HDC的N端氨基酸序列完全一致。推导的氨基酸序列与酿酒球菌HDC的同源性为98%。用8M尿素溶液处理重组酶活力。复性后的HdcA比活力为3.6×10~(-4)单位/mg，最适pH为4.8。转录本分析表明，hdcA在低pH低氧条件下可在静止相细胞中表达。(5)直接从草莓汁中扩增的16S rDNA片段的DGGE分析表明，肉汁中存在类杆菌、梭杆菌、鹅肝菌和梭状芽孢杆菌，表明肉汁中存在不可培养的微生物。(6)发酵后期的浮游鲫鱼，发酵后期的优势菌群是乳杆菌，早期的优势菌群是乳杆菌。较少

(1)Chemical composition of fish sauce produced in Tobishima Island are NaCl 20.7%, VBN 181mg/100g, lactic acid 1,620mg/100g, glutamic acid 1,322mg/100g, histamine 163mg/100mg and halophilic histamine-producing bacterium of Tetragenococus muriaticus appeared in the early stage of fermentation, while T.halophilus appeared throughout the period.(2)Histamine formation in cultures of Tetragenococcus muriaticus was observed in low acidity (pH 5.8), O_2 limiting conditions with optimal NaCl and glucose concentrations of 5-7% (w/v) and above 1%, respectively. Histamine formation could not be prevented even at 20% (w/v) NaCl.(3)A histidine decarboxylase from Tetragenococcus muriaticus was purified to homogeneity, for the first time. The pure enzyme consisted of two polypeptide chains with molecular mass of 28.8 and 13.4kDa. The N-terminal amino acid sequences of these polypeptides highly correlated with those of the alpha-and beta-chains of other Gram-positive bacterial histidine decarboxylases … More . The optimum and stable pH for the enzyme was 4.5-7.0 and 4.0-7.0, respectively. The enzyme activity decreased with the addition of NaCl.(4)The gene co d ing histidine decarboxylase (HDC) has been cloned by EcoRI fragment of chromosomal DNA from Tetragenococcus muriaticus. Sequence analysis of this fragment identified two open reading frames (ORFs). The first ORF (hdcA) encoded 316 amino acid residue s and it was identical to N-terminal amino acid sequence of HDC from T.muriaticus. The deduced amino acid sequence was 98% identity with HDC of Oenococcus oeni. Enzyme activity was reconstituted by treatment with 8M urea solution. The specific activity of renatured HdcA was 3.6×10^<-4> unit/mg and pH optimum at 4.8. The transcript analysis revealed that the hdcA was expressed in stationary-phase cell under O_2-limiting and low pH condition.(5)DGGE analysis of 16S rDNA fragments amplified directly from kusaya gravy revealed the existence of Bacteroides, Fusobacterium, Eggerthela lenta, and Clostridium, suggesting that unculturable organisms prevail in the gravy.(6)Dominant microflora of funazushi crucian carp fermented with rice, were Lactobacillus kefir in the late stage of fermentation, and L.alimentarius in the early stage. Less