• 한국미생물생명공학회:학술대회논문집
• /
• 한국미생물생명공학회 1979년도 추계학술대회 심포지움
• /
• pp.246.1-246
• /
• 1979

A glucose-limited “pH-stat” continuous culture study of Lactobacillus bulgaricus NLS-4 in an anaerobic condition showed the marked effects of environmental pH on end products, fermentation blances and bioenergetic aspects of the organism. Lactic acid was the major end product of fermentation with minor products, such as acetic acid, formic acid and ethanol throughout the pH range tested. In acidic conditions below pH 6.5, a typi-cal pattern of homofermentation was revealed whereas in alkaline conditions, the metabolic pattern was changed from homofermentation to heterofermentation and led to acquire much energy. This metabolic change was likely due to the pH-dependent lactate dehydrogenase activity. Molar growth yields (Yglc=35.5-44.4) and YATP, $18.5\pm2.5$ in average which was 80％ higher than the value ever postulated seemed to be accounted for less requirement of maintenance energy of the organism in the culture conditions.

• Applied Biological Chemistry
• /
• 제12권
• /
• pp.57-67
• /
• 1969

1. Furyl furamide 가 여름철 김치세균에 미치는 영향을 보기 위하여 두가지 여름김치에서 분리(分離)한 세균 Bacillus group 과 Lactic acid bacteria중 Bac. megaterium, Bac. subtilis 그리고 Bac. licheniformis등이 발효 초기(初期)의 젓갈김치에 우세 하였고 국물김치에서는 Lact. plantarum 과 Lact. buhneri등이 시종(始終) 매우 우세하였다. 2. 김치에서 분리(分離)된 Bacillus group 은 10 p.p.m. 이하(以下)의 AF-2 저농도(低濃度)에서 대단히 민감(敏感)하게 억제되었으나 Lactic acid bacteria의 group은 50 p.p.m.의 고농도(高濃度)에서도 저항(抵抗)하고 있었다. 3. 김치의 AF-2 첨가허용농도(添加許容濃度)는 최고(最高) 10 p.p.m.을 넘지 않아야 할 것이다. 4. 김치에 첨가(添加)된 고농도(高濃度)(50 p.p.m.)의 AF-2는 김치 발효를 heterofermentation 에서 Homofermentation으로 변화(變化)시키는 경향이 있었다. 5. AF-2 10 p.p.m. 농도(濃度)의 김치에서 bacterial flora는 약간 영향(影響)을 받고 있었으나, 50 p.p.m.의 고농도(高濃度)에서도 하절(夏節)김치의 산패(酸敗)는 억제할수가 없었다. 6. $23^{\circ}{\sim}25^{\circ}C$ 상태의 김치발효액중(醱酵液中)의 AF-2 소장(消長)은 산성(酸性)에서 비교적(比較的) 안전(安全)하다고 하나 4 일후(日後)에 약(約) 25%가 감소(減少)되고 pH 변화곡선(變化曲線)과 거의 평행(平行)한 변화(變化)를 보였다.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제9권4호
• /
• pp.303-308
• /
• 2004

We isolated a novel lactic acid bacterium from a Korean traditional fermented food, soybean paste. The newly isolated strain, dubbed RKY2, grew well on glucose, sucrose, galactose, and fructose, but it could not utilize xylose, starch, or glycerol. When the partially amplified 16S rDNA sequence (772 bp) of the strain RKY2 was compared with 10 reference strains, it was found to be most similar to Lactobacillus pentosus JCM $1588^T$, with 99.74% similarity. There-fore, the strain RKY2 was renamed Lactobacillus sp. RKY2, which has been deposited in the Korean Collection for Type Cultures as KCTC 10353BP. Lactobacillus sp. RKY2 was found to be a homofermentative lactic acid bacterium, because its end-product from glucose metabolism was found to be mainly lactic acid. It could produce more than 90 g/L of lactic acid from MRS medium supplemented with 100 g/L of glucose, with 5.2 g $L^-1$ $h^-1$ of productivity and 0.95 g/g of lactic acid yield.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제10권1호
• /
• pp.23-28
• /
• 2005

Lactic acid is a green chemical that can be used as a raw material for biodegradable polymer. To produce lactic acid through microbial fermentation, we previously screened a novel lactic acid bacterium. In this work, we optimized lactic acid fermentation using a newly isolated and homofermentative lactic acid bacterium. The optimum medium components were found to be glucose, yeast extract, $(NH_4)_{2}HPO_4,\;and\;MnSO_4$. The optimum pH and temperature for a batch culture of Lactobacillus sp. RKY2 was found to be 6.0 and $36^{\circ}C$, respectively. Under the optimized culture conditions, the maximum lactic acid concentration (153.9 g/L) was obtained from 200 g/L of glucose and 15 g/L of yeast extract, and maximum lactic acid productivity ($6.21\;gL^{-1}h^{-1}$) was obtained from 100 g/L of glucose and 20 g/L of yeast extract. In all cases, the lactic acid yields were found to be above 0.91 g/g. This article provides the optimized conditions for a batch culture of Lactobacillus sp. RKY2, which resulted in highest productivity of lactic acid.

• 한국버섯학회지
• /
• 제11권4호
• /
• pp.187-193
• /
• 2013

A galactose fermentation bacterium producing lactose from red seaweed, which was known well to compromise the galactose as main reducing sugar, was isolated from button mushroom bed in Buyeo-Gun, Chungchugnamdo province. The lactic acid bacteria MONGB-2 was identified as Lactobacillus paracasei subsp. tolerans by analysis of 16S rRNA gene sequence. When the production of lactic acid and acetic acid by L. paracasei MONGB-2 was investigated by HPLC analysis with various carbohydrates, the strain MONGB-2 efficiently convert the glucose and galactose to lactic acid with the yield of 18.86 g/L and 18.23 g/L, respectively and the ratio of lactic acid to total organic acids was 1.0 and 0.91 g/g for both substrates. However, in the case of acetic acid fermentation, other carbohydrates besides galactose and red seaweed hydrolysate could not be totally utilized as carbon sources for acetic acid production by the strain. The lactic acid production from glucose and galactose in the fermentation time courses was gradually enhanced upto 60 h fermentation and the maximal concentration reached to be 16-18 g/L from both substrates after 48 h of fermentation. The initial concentration of glucose and galactose were completely consumed within 36 h of fermentation, of which the growth of cell also was maximum level. In addition, the bioconversion of lactic acid from the red seaweed hydrolysate by L. paracasei MONGB-2 appeared to be about 20% levels of the initial substrates concentration and this results were entirely lower than those of galactose and glucose showed about 60% of conversion. The apparent results showed that L. paracasei MONGB-2 could produce the lactic acid with glucose as well as galactose by the homofermentation through EMP pathway.