In the present study, we assessed the bacteriological quality of water of drinking water sources in Kabale Municipality. A total of 28 water samples were collected from 14 water springs during the dry and wet season a...In the present study, we assessed the bacteriological quality of water of drinking water sources in Kabale Municipality. A total of 28 water samples were collected from 14 water springs during the dry and wet season and analyzed for determination of Escherichia coli (E. coli), and Total Heterotrophic Bacteria (THB) using the membrane filtration method. Most water springs located in less than 20 meters away from residential areas were associated with bacterial contamination. The mean concentrations of E. coli, total coliforms, and THB were 24.07 CFU/100 ml, 85.71 CFU/100 ml, and 197.07 CFU/100 ml, respectively in the wet season. While in the dry season, the mean concentrations were 2 CFU/100 ml, 10 CFU/100 ml, and 91 CFU/100 ml for E. coli, total coliforms, and THB, respectively. There were significant differences between CFU of total coliforms, HTB, between wet and dry seasons (p = 0.026). Samples collected and analyzed during the wet season for total coliforms did not conform to WHO drinking water quality guideline value of no detection per 100 ml. The study concludes that the majority of spring water sources are located in less than 20 meters away from residential areas with significant paved areas, the presence of septic tanks and pit latrines. Wet season significantly affects the quality of domestic water sources than the dry season. The study recommends that spring water should be treated before drinking due to high bacteria concentrations which makes it unsafe for consumption.展开更多
Vitamin B_(12)is a complex compound synthesized by microorganisms.The industrial production of vitamin B_(12)relies on specific microbial fermentation processes.E.coli has been utilized as a host for the de novo biosy...Vitamin B_(12)is a complex compound synthesized by microorganisms.The industrial production of vitamin B_(12)relies on specific microbial fermentation processes.E.coli has been utilized as a host for the de novo biosynthesis of vitamin B_(12),incorporating approximately 30 heterologous genes.However,a metabolic imbalance in the intricate pathway significantly limits vitamin B_(12)production.In this study,we employed multivariate modular metabolic engineering to enhance vitamin B_(12)production in E.coli by manipulating two modules comprising a total of 10 genes within the vitamin B_(12)biosynthetic pathway.These two modules were integrated into the chromosome of a chassis cell,regulated by T7,J23119,and J23106 promoters to achieve combinatorial pathway optimization.The highest vitamin B_(12)titer was attained by engineering the two modules controlled by J23119 and T7 promoters.The inclusion of yeast powder to the fermentation medium increased the vitamin B_(12)titer to 1.52 mg/L.This enhancement was attributed to the effect of yeast powder on elevating the oxygen transfer rate and augmenting the strain’s isopropyl-β-D-1-thiogalactopyranoside(IPTG)tolerance.Ultimately,vitamin B_(12)titer of 2.89 mg/L was achieved through scaled-up fermentation in a 5-liter fermenter.The strategies reported herein will expedite the development of industry-scale vitamin B_(12)production utilizing E.coli.展开更多
文摘In the present study, we assessed the bacteriological quality of water of drinking water sources in Kabale Municipality. A total of 28 water samples were collected from 14 water springs during the dry and wet season and analyzed for determination of Escherichia coli (E. coli), and Total Heterotrophic Bacteria (THB) using the membrane filtration method. Most water springs located in less than 20 meters away from residential areas were associated with bacterial contamination. The mean concentrations of E. coli, total coliforms, and THB were 24.07 CFU/100 ml, 85.71 CFU/100 ml, and 197.07 CFU/100 ml, respectively in the wet season. While in the dry season, the mean concentrations were 2 CFU/100 ml, 10 CFU/100 ml, and 91 CFU/100 ml for E. coli, total coliforms, and THB, respectively. There were significant differences between CFU of total coliforms, HTB, between wet and dry seasons (p = 0.026). Samples collected and analyzed during the wet season for total coliforms did not conform to WHO drinking water quality guideline value of no detection per 100 ml. The study concludes that the majority of spring water sources are located in less than 20 meters away from residential areas with significant paved areas, the presence of septic tanks and pit latrines. Wet season significantly affects the quality of domestic water sources than the dry season. The study recommends that spring water should be treated before drinking due to high bacteria concentrations which makes it unsafe for consumption.
基金supported by the National Key R&D Program of China(2018YFA0903700)the National Natural Science Foundation of China(22178372,22208367)+2 种基金National Science Fund for Distinguished Young Scholars(22325807)the Tianjin Synthetic Biotechnology Innovation Capacity Improvement Project(TSBICIP-KJGG-011,TSBICIP-CXRC-055,TSBICIP-PTJJ-007)Youth Innovation Promotion Association,Chinese Academy of Sciences(2020182).
文摘Vitamin B_(12)is a complex compound synthesized by microorganisms.The industrial production of vitamin B_(12)relies on specific microbial fermentation processes.E.coli has been utilized as a host for the de novo biosynthesis of vitamin B_(12),incorporating approximately 30 heterologous genes.However,a metabolic imbalance in the intricate pathway significantly limits vitamin B_(12)production.In this study,we employed multivariate modular metabolic engineering to enhance vitamin B_(12)production in E.coli by manipulating two modules comprising a total of 10 genes within the vitamin B_(12)biosynthetic pathway.These two modules were integrated into the chromosome of a chassis cell,regulated by T7,J23119,and J23106 promoters to achieve combinatorial pathway optimization.The highest vitamin B_(12)titer was attained by engineering the two modules controlled by J23119 and T7 promoters.The inclusion of yeast powder to the fermentation medium increased the vitamin B_(12)titer to 1.52 mg/L.This enhancement was attributed to the effect of yeast powder on elevating the oxygen transfer rate and augmenting the strain’s isopropyl-β-D-1-thiogalactopyranoside(IPTG)tolerance.Ultimately,vitamin B_(12)titer of 2.89 mg/L was achieved through scaled-up fermentation in a 5-liter fermenter.The strategies reported herein will expedite the development of industry-scale vitamin B_(12)production utilizing E.coli.
