This study was performed to improve the efficiency of production of bioemulsifier, which were produced by newly screened Pseudomonas aeruginosa YPJ80. Two vegetable oil, olive oil and soybean oil, were compared as carbon source. On cell growth, olive oil was better than soybean oil. Optical densitie...
This study was performed to improve the efficiency of production of bioemulsifier, which were produced by newly screened Pseudomonas aeruginosa YPJ80. Two vegetable oil, olive oil and soybean oil, were compared as carbon source. On cell growth, olive oil was better than soybean oil. Optical densities of cell broth at wave length of 600 nm, were reached to 14 and 11.4 each after 72 hr cultivation. But, rhamnose concentration, SED, and SED/rhamnose ratio were higher when soybean oil was used as a carbon source than olive oil. The final values are 1,800 mg/L, 620, and 0.34 L/mg, respectively. So, soybean oil was better carbon source for the production of bioemulsifier from P. aeruginosa YPJ80. For the purpose to develop the efficient separation system of bioemulsifier from culture broth, 3 typical precifitation methods and 2 extraction methods were examined. The recovery of bioemulsifier was determined by ratio of SED after separation onto SED of cell removed culture broth. The best methods for separtion of bioemulsifier was chloroform/methanol extration, and the recovery was ca. 40\%. Acidification was also good separation methods, and the recovery was ca. 34\%. These two methods can use at a time, and it may rise the recovery. From the random mutation, 11 rhamnolipids deficient mutants and 1 positive mutant which show better emulsifying activity than wildtype were isolated and screened. After 36 hr cultivation on triptic soy broth, the positive mutant shows 1.5 fold higher SED than wildtype. But the ability of lowering suface tension was worth. It seemed that these results were caused by the change of bioemulsifier and/or prduction of other emulsifier, and/or the change of ratio of 2 types of rhamnolipids. When the positive mutant and wildtype strain were cultivated in total 20 g/L glucose containing tryptic soy broth, wildtype showed higher final cell growth, rhamnose concentration, SED. But initial rhamnolipids synthesis rate of the mutant until first 4 hour was fast as 380.6 mg rhamnose/g cell$\cdot$h, that was ca. 50 \% higher value than that of wildtype. When vegetable oils were used as carbon source, also wildtype showed her final rhamnose concentration and SED. But the ratios of SED to mnose concentration of the mutant was better than wildtype. The abilities of pH-stat substrate suplementation method was investigated for two semi-defined media, medium I and R medium for the purpose to select medium for fed-batch cultivation. From the pH profile, R medium was selected. When 700 g/L glucose and 20 g/L $MgSO_4 \cdot 7H_2O$ were used as feeding solution and 2N NaOH was used for pH adjust alkali solution, there is no increasement of cell growth and rhamnose concentration and nitrogen source was exhausted too early. To prevent early consumption of nitrogen source, change the feeding solution to 700 g/L glucose, 20 g/L $MgSO_4 \cdot 7H_2O$ and 5 g/L yeast extract, and alkali solution to 75\% ammonia water. Then, the cell growed to 75.5 of optical density at 600 nm after 25 hour cultivation which was the highst value among reported. Rhamnose concentration was increased to 1,600 mg/L which was ca. 2.5 fold higher value than that of batch cultivation.
This study was performed to improve the efficiency of production of bioemulsifier, which were produced by newly screened Pseudomonas aeruginosa YPJ80. Two vegetable oil, olive oil and soybean oil, were compared as carbon source. On cell growth, olive oil was better than soybean oil. Optical densities of cell broth at wave length of 600 nm, were reached to 14 and 11.4 each after 72 hr cultivation. But, rhamnose concentration, SED, and SED/rhamnose ratio were higher when soybean oil was used as a carbon source than olive oil. The final values are 1,800 mg/L, 620, and 0.34 L/mg, respectively. So, soybean oil was better carbon source for the production of bioemulsifier from P. aeruginosa YPJ80. For the purpose to develop the efficient separation system of bioemulsifier from culture broth, 3 typical precifitation methods and 2 extraction methods were examined. The recovery of bioemulsifier was determined by ratio of SED after separation onto SED of cell removed culture broth. The best methods for separtion of bioemulsifier was chloroform/methanol extration, and the recovery was ca. 40\%. Acidification was also good separation methods, and the recovery was ca. 34\%. These two methods can use at a time, and it may rise the recovery. From the random mutation, 11 rhamnolipids deficient mutants and 1 positive mutant which show better emulsifying activity than wildtype were isolated and screened. After 36 hr cultivation on triptic soy broth, the positive mutant shows 1.5 fold higher SED than wildtype. But the ability of lowering suface tension was worth. It seemed that these results were caused by the change of bioemulsifier and/or prduction of other emulsifier, and/or the change of ratio of 2 types of rhamnolipids. When the positive mutant and wildtype strain were cultivated in total 20 g/L glucose containing tryptic soy broth, wildtype showed higher final cell growth, rhamnose concentration, SED. But initial rhamnolipids synthesis rate of the mutant until first 4 hour was fast as 380.6 mg rhamnose/g cell$\cdot$h, that was ca. 50 \% higher value than that of wildtype. When vegetable oils were used as carbon source, also wildtype showed her final rhamnose concentration and SED. But the ratios of SED to mnose concentration of the mutant was better than wildtype. The abilities of pH-stat substrate suplementation method was investigated for two semi-defined media, medium I and R medium for the purpose to select medium for fed-batch cultivation. From the pH profile, R medium was selected. When 700 g/L glucose and 20 g/L $MgSO_4 \cdot 7H_2O$ were used as feeding solution and 2N NaOH was used for pH adjust alkali solution, there is no increasement of cell growth and rhamnose concentration and nitrogen source was exhausted too early. To prevent early consumption of nitrogen source, change the feeding solution to 700 g/L glucose, 20 g/L $MgSO_4 \cdot 7H_2O$ and 5 g/L yeast extract, and alkali solution to 75\% ammonia water. Then, the cell growed to 75.5 of optical density at 600 nm after 25 hour cultivation which was the highst value among reported. Rhamnose concentration was increased to 1,600 mg/L which was ca. 2.5 fold higher value than that of batch cultivation.
주제어
#Pseudomonas aeruginosa Rhamnolipids Fed-batch Mutation 유가식배양 변이
※ AI-Helper는 부적절한 답변을 할 수 있습니다.