Aeromonas hydrophila 4AK4 was grown on mixed substrates of soybean oil and lauric acid for the production of polyhydroxyalkanoate copolymer consisting of 3 hydroxybutyrate (3HB) and 3 hydroxyhexanoate (3HHx). A m...Aeromonas hydrophila 4AK4 was grown on mixed substrates of soybean oil and lauric acid for the production of polyhydroxyalkanoate copolymer consisting of 3 hydroxybutyrate (3HB) and 3 hydroxyhexanoate (3HHx). A maximal poly(3 hydroxybutyrate co 3 hydroxyhexanoate) (PHBHHx) content of 49.13% in dry cells was obtained in a shake flask culture. PHBHHx of 6.26 g/L was produced in a fermentation experiment over 48 h on a sole carbon source containing 100 g/L soybean oil, while 12.40 g/L PHBHHx was produced on a mixed carbon source containing 80 g/L soybean and 20 g/L lauric acid over the same period of time, resulting in a polyhydroxyalkanoate (PHA) productivity of 0.25 g/(L·h). The results show that mixed carbon sources are suitable for industrialized production of PHBHHx from A. hydrophila 4AK4, as the mixed carbon sources also overcome the foaming problem that occurs when lauric acid is employed as a sole carbon source in PHBHHx production. 展开更多
为提高剩余污泥水解酸化过程中挥发性脂肪酸(VFAs)的累积,从剩余污泥中分离产蛋白酶活力较高的耐碱细菌,并构建产蛋白酶混合菌系.将其接种于碱性(p H 10.0)发酵剩余污泥的不同发酵时期,评价其对溶解性有机化合物和VFAs累积的影响,探讨...为提高剩余污泥水解酸化过程中挥发性脂肪酸(VFAs)的累积,从剩余污泥中分离产蛋白酶活力较高的耐碱细菌,并构建产蛋白酶混合菌系.将其接种于碱性(p H 10.0)发酵剩余污泥的不同发酵时期,评价其对溶解性有机化合物和VFAs累积的影响,探讨利用剩余污泥生产VFAs的最佳条件.从剩余污泥中分离到2株产蛋白酶活力较高的耐碱细菌,并构建产蛋白酶混合菌系.在发酵初期接种混合菌系效果最显著,且可缩短发酵启动时间2 d.发酵初期接种混合菌系后,溶解性蛋白质和VFAs质量浓度在第8天均达到最高值,分别为未接种混合菌系样品中相应值的1.25和1.41倍,分别占溶解性化学需氧量(SCOD)总量的29.87%和44.54%.乙酸和丙酸为剩余污泥水解酸化过程中VFAs的主要组分,分别占VFAs总量的50.69%和18.19%.展开更多
The intensive use of nitrogen fertilizers in Algeria caused a pollution of the waters by nitrates. This concentration reached in the region of Collo （Wilaya of Skikda, Algeria） 570 mg/L, which is beyond the WHO stan...The intensive use of nitrogen fertilizers in Algeria caused a pollution of the waters by nitrates. This concentration reached in the region of Collo （Wilaya of Skikda, Algeria） 570 mg/L, which is beyond the WHO standard （50 mg/L）. This has negative consequences on human health （Methemoglobinemia） and on the environment （eutrophication）. In our works, we studied the elimination of this pollution with the use of a mixed culture of microorganisms. We replaced the standard synthetic carbon source and the nutritious medium by date powder. This contains minerals and sugars that can enhance bacterial growth. Our study showed that the effectiveness of denitrification is proportional to bacterial growth. It rises exponentially after a latency period of 8 hours. During the reaction of degradation we noticed a rise in pH in our engine, it moved from 7.00 to 8.38. In studying the influence of initial pH on the denitrification of the microorganisms, we observed that the ion hydrogen concentration modified the growth rate of bacteria and degradation of nitrates. An acid pH, the reduction of nitrates is incomplete; this is accounted for the accumulation of nitrous and nitric oxide that interferes in the reaction of denitrification. The velocity of the nitrate reduction is less important in an acid pH （0.0096 g.L^-l.h^-1） than in a basic pH （0.013 g.L^-1.h^-1）. The denitrification is optimal at temperature 35 ℃ for a ratio C/N = 2.5. In these conditions 95% of the nitrate initial quantity is eliminated after approximately 100 hour treatment.展开更多
基金Supported by"985"Foundation of Tsinghua University
文摘Aeromonas hydrophila 4AK4 was grown on mixed substrates of soybean oil and lauric acid for the production of polyhydroxyalkanoate copolymer consisting of 3 hydroxybutyrate (3HB) and 3 hydroxyhexanoate (3HHx). A maximal poly(3 hydroxybutyrate co 3 hydroxyhexanoate) (PHBHHx) content of 49.13% in dry cells was obtained in a shake flask culture. PHBHHx of 6.26 g/L was produced in a fermentation experiment over 48 h on a sole carbon source containing 100 g/L soybean oil, while 12.40 g/L PHBHHx was produced on a mixed carbon source containing 80 g/L soybean and 20 g/L lauric acid over the same period of time, resulting in a polyhydroxyalkanoate (PHA) productivity of 0.25 g/(L·h). The results show that mixed carbon sources are suitable for industrialized production of PHBHHx from A. hydrophila 4AK4, as the mixed carbon sources also overcome the foaming problem that occurs when lauric acid is employed as a sole carbon source in PHBHHx production.
文摘为提高剩余污泥水解酸化过程中挥发性脂肪酸(VFAs)的累积,从剩余污泥中分离产蛋白酶活力较高的耐碱细菌,并构建产蛋白酶混合菌系.将其接种于碱性(p H 10.0)发酵剩余污泥的不同发酵时期,评价其对溶解性有机化合物和VFAs累积的影响,探讨利用剩余污泥生产VFAs的最佳条件.从剩余污泥中分离到2株产蛋白酶活力较高的耐碱细菌,并构建产蛋白酶混合菌系.在发酵初期接种混合菌系效果最显著,且可缩短发酵启动时间2 d.发酵初期接种混合菌系后,溶解性蛋白质和VFAs质量浓度在第8天均达到最高值,分别为未接种混合菌系样品中相应值的1.25和1.41倍,分别占溶解性化学需氧量(SCOD)总量的29.87%和44.54%.乙酸和丙酸为剩余污泥水解酸化过程中VFAs的主要组分,分别占VFAs总量的50.69%和18.19%.
文摘The intensive use of nitrogen fertilizers in Algeria caused a pollution of the waters by nitrates. This concentration reached in the region of Collo （Wilaya of Skikda, Algeria） 570 mg/L, which is beyond the WHO standard （50 mg/L）. This has negative consequences on human health （Methemoglobinemia） and on the environment （eutrophication）. In our works, we studied the elimination of this pollution with the use of a mixed culture of microorganisms. We replaced the standard synthetic carbon source and the nutritious medium by date powder. This contains minerals and sugars that can enhance bacterial growth. Our study showed that the effectiveness of denitrification is proportional to bacterial growth. It rises exponentially after a latency period of 8 hours. During the reaction of degradation we noticed a rise in pH in our engine, it moved from 7.00 to 8.38. In studying the influence of initial pH on the denitrification of the microorganisms, we observed that the ion hydrogen concentration modified the growth rate of bacteria and degradation of nitrates. An acid pH, the reduction of nitrates is incomplete; this is accounted for the accumulation of nitrous and nitric oxide that interferes in the reaction of denitrification. The velocity of the nitrate reduction is less important in an acid pH （0.0096 g.L^-l.h^-1） than in a basic pH （0.013 g.L^-1.h^-1）. The denitrification is optimal at temperature 35 ℃ for a ratio C/N = 2.5. In these conditions 95% of the nitrate initial quantity is eliminated after approximately 100 hour treatment.
