scholarly journals Development of a semi-defined medium for high cell density cultivation of Escherichia coli in shake flasks: Part 1

2016 ◽  
Author(s):  
Wenfa Ng ◽  
Yen-Peng Ting
Keyword(s):  
Escherichia Coli ◽  
Cell Density ◽  
Yeast Extract ◽  
High Cell Density ◽  
Defined Medium ◽  
High Cell ◽  
High Cell Density Cultivation ◽  
E Coli ◽  
Carbon And Nitrogen ◽  
Shake Flasks

Sufficient quantities of cells of consistent characteristics are needed for studying biological processes (at the population level) in many areas of applied microbiology research. However, generating the requisite biomass amount by cell culture is usually the rate-limiting step of the experiment given the relatively low biomass yield of many commercial culture media in shake flasks. This work reports the formulation of a semi-defined medium that enabled aerobic high cell density cultivation of Escherichia coli DH5α (ATCC 53868) in shake flasks. The formulated medium (FM) comprises: a buffer system (K2HPO4: 12.54 g/L and KH2PO4: 2.31 g/L); vitamins and trace elements (yeast extract: 12.0 g/L); salts (NaCl: 5.0 g/L and MgSO4: 0.24 g/L); and carbon and nitrogen sources (D-Glucose: 6.0 g/L and NH4Cl: 1.5 g/L). Notable characteristics of this medium are: high buffer capacity (89 mM phosphate), 1:1 molar ratio between D-Glucose and NH4Cl, and yeast extract providing trace elements and a secondary source of carbon and nitrogen. Preliminary data revealed that an OD600nm of 9 was attained after 24 hours of cultivation at 37 oC, with glucose and NH4Cl as the main nutritional sources. At 48 hours, the OD600nm reached a maximal value of 11 with yeast extract providing the necessary nutrients for cell growth and biomass formation. The broth’s pH varied between 5.5 and 7.8 during cultivation. For comparison, the maximum OD600nm of E. coli grown in three commonly used complex media: Nutrient Broth, LB Lennox, and Tryptic Soy Broth (TSB) were 1.4, 3.2 and 9.2, respectively, under identical culture conditions. Finally, FM maintained the viability of a larger population of cells for three days - compared to a population collapse observed in TSB after one day. Collectively, the present findings suggest that the formulated medium may find use as a high cell density aerobic growth medium for E. coli in shake flasks. Part 2 of this work describes improvements in medium performance - specifically, higher cell yield as well as a shorter diauxic lag phase and total culture period – achieved through a small reduction in D-Glucose and NH4Cl concentrations in the medium composition. A preprint of the work is available at https://peerj.com/preprints/117/.

scholarly journals Development of a semi-defined medium for high cell density cultivation of Escherichia coli in shake flasks: Part 1

2016 ◽  
Author(s):  
Wenfa Ng ◽  
Yen-Peng Ting
Keyword(s):  
Escherichia Coli ◽  
Cell Density ◽  
Yeast Extract ◽  
High Cell Density ◽  
Defined Medium ◽  
High Cell ◽  
High Cell Density Cultivation ◽  
E Coli ◽  
Carbon And Nitrogen ◽  
Shake Flasks

Sufficient quantities of cells of consistent characteristics are needed for studying biological processes (at the population level) in many areas of applied microbiology. However, generating the requisite biomass by cell culture is usually the rate-limiting step of a project given the relatively low biomass yield of many commercial culture media in shake flasks. This work reports the formulation of a semi-defined medium that enabled aerobic high cell density cultivation of Escherichia coli DH5α (ATCC 53868) in shake flasks. The formulated medium (FM) comprises: a buffer system (K2HPO4: 12.54 g/L and KH2PO4: 2.31 g/L); vitamins and trace elements (yeast extract: 12.0 g/L); salts (NaCl: 5.0 g/L and MgSO4: 0.24 g/L); and carbon and nitrogen sources (D-Glucose: 6.0 g/L and NH4Cl: 1.5 g/L). Notable characteristics of this medium are: high buffer capacity (89 mM phosphate), 1:1 molar ratio between D-Glucose and NH4Cl, and yeast extract providing trace elements and a secondary source of carbon and nitrogen. Preliminary data revealed that an OD600nm of 9 was attained after 24 hours of cultivation at 37 oC, with glucose and NH4Cl as the main nutrients. At 48 hours, the OD600nm reached a maximum value of 11 with yeast extract providing the necessary nutrients for cell growth and biomass formation. The broth’s pH varied between 5.5 and 7.8 during cultivation. For comparison, the maximum OD600nm of E. coli grown in three commonly used complex media: Nutrient Broth, LB Lennox, and Tryptic Soy Broth (TSB) were 1.4, 3.2 and 9.2, respectively, under identical culture conditions. Finally, FM maintained the viability of a larger population of cells for three days - compared to a population collapse observed in TSB after one day. Collectively, the present findings suggested that the formulated medium might find use as a high cell density aerobic growth medium for E. coli in shake flasks. Part 2 of this work describes improvements in medium performance - specifically, higher cell yield as well as a shorter diauxic lag phase and total culture period – achieved through a small reduction in D-Glucose and NH4Cl concentrations in the medium composition. An abstract preprint of Part 2 is available at https://peerj.com/preprints/117/

scholarly journals Development of a semi-defined medium for high cell density cultivation of Escherichia coli in shake flasks: Part 1

2017 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Escherichia Coli ◽  
Cell Density ◽  
Yeast Extract ◽  
High Cell Density ◽  
Defined Medium ◽  
High Cell ◽  
High Cell Density Cultivation ◽  
E Coli ◽  
Carbon And Nitrogen ◽  
Shake Flasks

Sufficient quantities of cells of consistent characteristics are needed for studying biologicalprocesses (at the population level ) in many areas of applied microbiology. However, generating the requisite biomass by cell culture is usually the rate-limiting step of a project given the relatively low biomass yield of many commercial culture media in shake flask culture systems. This work reports the formulation of a semi-defined medium that enabled aerobic high cell density cultivation of Escherichia coli DH5α (ATCC 53868) in shake flasks. The formulated medium (FM) comprises: a buffer system (K2HPO4 : 12.54 g/L and KH2 PO4 : 2.31 g/L); vitamins and trace elements (yeast extract: 12.0 g/L); salts (NaCl: 5.0 g/L and MgSO4 : 0.24 g/L); and carbon and nitrogen sources (D-Glucose: 6.0 g/L and NH4Cl: 1.5 g/L). Notable characteristics of this medium are: high buffer capacity (89 mM phosphate), 1:1 molar ratio between D-Glucose and NH4Cl, and yeast extract providing trace elements and a secondary source of carbon and nitrogen. Preliminary data revealed an OD 600nm of 9 after 24 hours of cultivation at 37 oC, presumably with glucose and NH4Cl as the main nutrients. At 48 hours, an OD 600nm of 11 was attained with yeast extract providing the necessary nutrients for cell growth and biomass formation. The broth’s pH varied between 5.5 and 7.8 during cultivation. On the other hand, the maximum OD 600nm of E. coli grown in three commonly used complex media: Nutrient Broth, LB Lennox, and Tryptic Soy Broth (TSB) were 1.4, 3.2 and 9.2, respectively, under identical culture conditions. Finally, FM maintained the viability of a larger population of cells for three days, compared to a population collapse in TSB broth after one day. Collectively, the results suggested that the formulated medium might find use as a high cell density aerobic growth medium for E. coli in shake flasks. Part 2 of this work describes improvements in medium performance ; specifically, higher cell yield as well as a shorter diauxic lag phase and total culture period achieved through a small reduction in D-Glucose and NH4Cl concentrations in the medium composition. An abstract preprint of Part 2 is available at https://peerj.com/preprints/117/

scholarly journals Development of a semi-defined medium for high cell density cultivation of Escherichia coli in shake flasks: Part 1

2017 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Escherichia Coli ◽  
Cell Density ◽  
Yeast Extract ◽  
High Cell Density ◽  
Defined Medium ◽  
High Cell ◽  
High Cell Density Cultivation ◽  
E Coli ◽  
Carbon And Nitrogen ◽  
Shake Flasks

Sufficient quantities of cells of consistent characteristics are needed for studying biologicalprocesses (at the population level ) in many areas of applied microbiology. However, generating the requisite biomass by cell culture is usually the rate-limiting step of a project given the relatively low biomass yield of many commercial culture media in shake flask culture systems. This work reports the formulation of a semi-defined medium that enabled aerobic high cell density cultivation of Escherichia coli DH5α (ATCC 53868) in shake flasks. The formulated medium (FM) comprises: a buffer system (K2HPO4 : 12.54 g/L and KH2 PO4 : 2.31 g/L); vitamins and trace elements (yeast extract: 12.0 g/L); salts (NaCl: 5.0 g/L and MgSO4 : 0.24 g/L); and carbon and nitrogen sources (D-Glucose: 6.0 g/L and NH4Cl: 1.5 g/L). Notable characteristics of this medium are: high buffer capacity (89 mM phosphate), 1:1 molar ratio between D-Glucose and NH4Cl, and yeast extract providing trace elements and a secondary source of carbon and nitrogen. Preliminary data revealed an OD 600nm of 9 after 24 hours of cultivation at 37 oC, presumably with glucose and NH4Cl as the main nutrients. At 48 hours, an OD 600nm of 11 was attained with yeast extract providing the necessary nutrients for cell growth and biomass formation. The broth’s pH varied between 5.5 and 7.8 during cultivation. On the other hand, the maximum OD 600nm of E. coli grown in three commonly used complex media: Nutrient Broth, LB Lennox, and Tryptic Soy Broth (TSB) were 1.4, 3.2 and 9.2, respectively, under identical culture conditions. Finally, FM maintained the viability of a larger population of cells for three days, compared to a population collapse in TSB broth after one day. Collectively, the results suggested that the formulated medium might find use as a high cell density aerobic growth medium for E. coli in shake flasks. Part 2 of this work describes improvements in medium performance ; specifically, higher cell yield as well as a shorter diauxic lag phase and total culture period achieved through a small reduction in D-Glucose and NH4Cl concentrations in the medium composition. An abstract preprint of Part 2 is available at https://peerj.com/preprints/117/

scholarly journals Development of a semi-defined medium for high cell density cultivation of Escherichia coli in shake flask culture system: Part 1

2013 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Cell Density ◽  
Yeast Extract ◽  
Shake Flask ◽  
High Cell Density ◽  
Defined Medium ◽  
High Cell ◽  
High Cell Density Cultivation ◽  
E Coli ◽  
Carbon And Nitrogen ◽  
Shake Flasks

Sufficient quantities of cells of consistent characteristics are needed for studying processes - at the population level and beyond - in many areas of applied microbiology research. Nevertheless, given the relatively low biomass yield of many commercial culture media in shake flasks, producing the requisite biomass by cell culture is generally the rate-limiting step. This work reports the formulation of a semi-defined medium that enabled aerobic high cell density cultivation of Escherichia coli DH5α (ATCC 53868) in shake flasks. The formulated medium (FM) comprises: a buffer system (K2HPO4: 12.54 g/L and KH2PO4: 2.31 g/L); vitamins and trace elements (yeast extract: 12.0 g/L); salts (NaCl: 5.0 g/L and MgSO4: 0.24 g/L); and carbon and nitrogen sources (D-Glucose: 6.0 g/L and NH4Cl: 1.5 g/L). Notable characteristics of this medium are: high buffer capacity (89 mM phosphate), 1:1 molar ratio between D-Glucose and NH4Cl, and yeast extract providing trace elements and a secondary source of carbon and nitrogen. Preliminary data revealed that an OD600nm of 9 was attained after 24 hours of cultivation at 37 oC – most probably fuelled by glucose and NH4Cl. At 48 hours, the OD600nm reached a maximal value of 11 with yeast extract providing the necessary nutrients for cell growth and biomass formation. The broth’s pH varied between 5.5 and 7.8 during cultivation. For comparison, the maximum OD600nm of E. coli grown in three commonly used complex media: Nutrient Broth, LB Lennox, and Tryptic Soy Broth (TSB) were 1.4, 3.2 and 9.2, respectively, under identical culture conditions. Finally, FM maintained the viability of a larger population for three days - compared to a population collapse observed in TSB after one day. Taken together, the present findings suggest that the formulated medium may find use as a high cell density aerobic growth medium for E. coli in shake flask.

scholarly journals Development of a semi-defined medium for high cell density cultivation of Escherichia coli in shake flask culture system: Part 1

2015 ◽  
Author(s):  
Wenfa Ng ◽  
Yen-Peng Ting
Keyword(s):  
Cell Density ◽  
Yeast Extract ◽  
Shake Flask ◽  
High Cell Density ◽  
Defined Medium ◽  
High Cell ◽  
High Cell Density Cultivation ◽  
E Coli ◽  
Carbon And Nitrogen ◽  
Shake Flasks

Sufficient quantities of cells of consistent characteristics are needed for studying processes - at the population level and beyond - in many areas of applied microbiology research. Nevertheless, given the relatively low biomass yield of many commercial culture media in shake flasks, producing the requisite biomass by cell culture is generally the rate-limiting step. This work reports the formulation of a semi-defined medium that enabled aerobic high cell density cultivation of Escherichia coli DH5α (ATCC 53868) in shake flasks. The formulated medium (FM) comprises: a buffer system (K2HPO4: 12.54 g/L and KH2PO4: 2.31 g/L); vitamins and trace elements (yeast extract: 12.0 g/L); salts (NaCl: 5.0 g/L and MgSO4: 0.24 g/L); and carbon and nitrogen sources (D-Glucose: 6.0 g/L and NH4Cl: 1.5 g/L). Notable characteristics of this medium are: high buffer capacity (89 mM phosphate), 1:1 molar ratio between D-Glucose and NH4Cl, and yeast extract providing trace elements and a secondary source of carbon and nitrogen. Preliminary data revealed that an OD600nm of 9 was attained after 24 hours of cultivation at 37 oC – most probably fuelled by glucose and NH4Cl. At 48 hours, the OD600nm reached a maximal value of 11 with yeast extract providing the necessary nutrients for cell growth and biomass formation. The broth’s pH varied between 5.5 and 7.8 during cultivation. For comparison, the maximum OD600nm of E. coli grown in three commonly used complex media: Nutrient Broth, LB Lennox, and Tryptic Soy Broth (TSB) were 1.4, 3.2 and 9.2, respectively, under identical culture conditions. Finally, FM maintained the viability of a larger population for three days - compared to a population collapse observed in TSB after one day. Taken together, the present findings suggest that the formulated medium may find use as a high cell density aerobic growth medium for E. coli in shake flask. Part 2 of this work describes improvements in medium performance - specifically, higher cell yield as well as a shorter diauxic lag phase and total culture period – achieved through a small reduction in D-Glucose and NH4Cl concentrations in the medium composition. A preprint of the work is available at https://peerj.com/preprints/117v1.

scholarly journals Development of a semi-defined medium for high cell density cultivation of Escherichia coli in shake flask culture system: Part 1

2013 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Cell Density ◽  
Yeast Extract ◽  
Shake Flask ◽  
High Cell Density ◽  
Defined Medium ◽  
High Cell ◽  
High Cell Density Cultivation ◽  
E Coli ◽  
Carbon And Nitrogen ◽  
Shake Flasks

Sufficient quantities of cells of consistent characteristics are needed for studying processes - at the population level and beyond - in many areas of applied microbiology research. Nevertheless, given the relatively low biomass yield of many commercial culture media in shake flasks, producing the requisite biomass by cell culture is generally the rate-limiting step. This work reports the formulation of a semi-defined medium that enabled aerobic high cell density cultivation of Escherichia coli DH5α (ATCC 53868) in shake flasks. The formulated medium (FM) comprises: a buffer system (K2HPO4: 12.54 g/L and KH2PO4: 2.31 g/L); vitamins and trace elements (yeast extract: 12.0 g/L); salts (NaCl: 5.0 g/L and MgSO4: 0.24 g/L); and carbon and nitrogen sources (D-Glucose: 6.0 g/L and NH4Cl: 1.5 g/L). Notable characteristics of this medium are: high buffer capacity (89 mM phosphate), 1:1 molar ratio between D-Glucose and NH4Cl, and yeast extract providing trace elements and a secondary source of carbon and nitrogen. Preliminary data revealed that an OD600nm of 9 was attained after 24 hours of cultivation at 37 oC – most probably fuelled by glucose and NH4Cl. At 48 hours, the OD600nm reached a maximal value of 11 with yeast extract providing the necessary nutrients for cell growth and biomass formation. The broth’s pH varied between 5.5 and 7.8 during cultivation. For comparison, the maximum OD600nm of E. coli grown in three commonly used complex media: Nutrient Broth, LB Lennox, and Tryptic Soy Broth (TSB) were 1.4, 3.2 and 9.2, respectively, under identical culture conditions. Finally, FM maintained the viability of a larger population for three days - compared to a population collapse observed in TSB after one day. Taken together, the present findings suggest that the formulated medium may find use as a high cell density aerobic growth medium for E. coli in shake flask. Part 2 of this work describes improvements in medium performance - specifically, higher cell yield as well as a shorter diauxic lag phase and total culture period – achieved through a small reduction in D-Glucose and NH4Cl concentrations in the medium composition. A preprint of the work is available at https://peerj.com/preprints/117v1.

scholarly journals Development of a semi-defined medium for high cell density cultivation of Escherichia coli in shake flask culture system

2015 ◽  
Author(s):  
Wenfa Ng ◽  
Yen-Peng Ting
Keyword(s):  
Escherichia Coli ◽  
Cell Density ◽  
Yeast Extract ◽  
High Cell Density ◽  
Growth Media ◽  
Buffer System ◽  
High Cell ◽  
High Cell Density Cultivation ◽  
E Coli ◽  
Carbon And Nitrogen

Microbes in environmental studies should be cultured in growth media with characteristics as close to their original habitat as possible, and which also allows a high cell density to be attained for providing enough cells in subsequent experiments. This in-progress report describes the formulation of a medium with an environmentally-relevant composition, and which also affords aerobic high cell density cultivation of Escherichia coli DH5α in shake flasks. The formulated medium comprises four components: a buffer system (K2HPO4: 12.54 g/L and KH2PO4: 2.31 g/L), vitamins (yeast extract: 12.0 g/L), salts (NaCl: 5.0 g/L and MgSO4: 0.24 g/L), and carbon and nitrogen sources (D-Glucose: 6.0 g/L and NH4Cl: 1.5 g/L). Notable characteristics of this medium were: high capacity phosphate buffer system (89 mM phosphate); 1:1 molar ratio between D-Glucose and NH4Cl; and yeast extract providing trace elements and a secondary carbon and nitrogen source. Growth experiments revealed that an OD600nm of 9 was attained after 24 hours of cultivation at 37 oC. This phase of growth was largely fuelled by glucose and NH4Cl. After 48 hours, the OD600nm reached 11, which was fuelled by the mixture of carbohydrates, lipids and proteins in yeast extract. Broth’s pH varied between 5.5 and 7.8 during cultivation, which was in the range conducive for growth of E. coli. In comparison, the OD600nm of E. coli reached 1.4, 3.2, and 9.2 for three commonly used complex media; Nutrient Broth, LB Lennox, and Tryptic Soy Broth, respectively, over 48 hours under identical culture conditions. In addition, the formulated medium was able to maintain a large viable cell population for a longer period of time (three days) relative to Tryptic Soy Broth. Thus, preliminary data suggested that the formulated medium holds potential for use as a high cell density aerobic growth medium for Gram-negative bacteria.

scholarly journals Development of a semi-defined medium for high cell density cultivation of Escherichia coli in shake flask culture system

2016 ◽  
Author(s):  
Wenfa Ng ◽  
Yen-Peng Ting
Keyword(s):  
Escherichia Coli ◽  
Cell Density ◽  
Yeast Extract ◽  
High Cell Density ◽  
Environmental Research ◽  
Buffer System ◽  
High Cell ◽  
High Cell Density Cultivation ◽  
E Coli ◽  
Carbon And Nitrogen

Microbes for environmental research should be cultured in growth media with characteristics as close to their original habitat as possible and, which also allows high cell density to be obtained - needed for providing sufficient cells in subsequent experiments. This report describes the formulation of a medium with an environmentally-relevant composition, and that affords aerobic high cell density cultivation of Escherichia coli DH5α in shake flasks. The formulated medium comprises four components: a buffer system (K2HPO4: 12.54 g/L and KH2PO4: 2.31 g/L), vitamins (yeast extract: 12.0 g/L), salts (NaCl: 5.0 g/L and MgSO4: 0.24 g/L), and carbon and nitrogen sources (D-Glucose: 6.0 g/L and NH4Cl: 1.5 g/L). Notable characteristics of this medium were: high capacity phosphate buffer system (89 mM phosphate); 1:1 molar ratio between D-Glucose and NH4Cl; and yeast extract providing trace elements and a secondary carbon and nitrogen source. Growth experiments revealed that an OD600nm of 9 was attained after 24 hours of cultivation at 37 oC. This phase of growth was most probably fuelled by glucose and NH4Cl. After 48 hours, the OD600nm reached 11, which was likely fuelled by a mixture of carbohydrates, lipids and proteins in yeast extract. Broth’s pH varied between 5.5 and 7.8 during cultivation, which was in the range conducive for growth of E. coli. In comparison, the OD600nm of E. coli reached 1.4, 3.2, and 9.2 for three commonly used complex media; Nutrient Broth, LB Lennox, and Tryptic Soy Broth, respectively, over 48 hours under identical culture conditions. In addition, the formulated medium was able to maintain a large viable cell population for a longer period of time (three days) compared to Tryptic Soy Broth. Thus, preliminary data suggested that the formulated medium holds potential for use as a high cell density aerobic growth medium for Gram-negative bacteria.

scholarly journals Formulation of a semi-defined medium for high cell density cultivation of Escherichia coli in shake flasks

2016 ◽  
Author(s):  
Wenfa Ng ◽  
Yen-Peng Ting
Keyword(s):  
Cell Density ◽  
Yeast Extract ◽  
High Cell Density ◽  
Nitrogen Sources ◽  
Buffer System ◽  
High Cell ◽  
Carbon And Nitrogen Sources ◽  
E Coli ◽  
Carbon And Nitrogen ◽  
Shake Flasks

Microbes for environmental research should be cultured in growth media with characteristics (e.g., pH, ionic strength, and organic and ionic composition) as close to their original habitat as possible. Additionally, the medium should also enable high cell density to be obtained - needed for providing sufficient cells in subsequent experiments. This in-progress report describes the formulation of a medium with an environmentally-relevant composition (lack of complex organics), and that allows aerobic high cell density cultivation of Escherichia coli DH5α in shake flasks. The formulated medium comprises four components: a buffer system (K2HPO4: 12.54 g/L and KH2PO4: 2.31 g/L), vitamins (yeast extract: 12.0 g/L), salts (NaCl: 5.0 g/L and MgSO4: 0.24 g/L), and carbon and nitrogen sources (D-Glucose: 6.0 g/L and NH4Cl: 1.5 g/L). Notable characteristics of this medium were: high capacity phosphate buffer system (89 mM phosphate); 1:1 molar ratio between D-Glucose and NH4Cl; and yeast extract providing trace elements and a secondary carbon and nitrogen source. Growth experiments revealed that an OD600nm of 9 was attained after 24 hours of cultivation at 37 oC. Glucose and NH4Cl serve as primary carbon and nitrogen sources for this phase of growth. After 48 hours, the OD600nm reached 11, where carbohydrates, lipids and proteins in yeast extract provided the nutrients for biomass formation. Broth’s pH varied between 5.5 and 7.8 during cultivation, which was in the range conducive for E. coli growth. In comparison, the OD600nm of E. coli reached 1.4, 3.2, and 9.2 in three commonly used complex media; Nutrient Broth, LB Lennox, and Tryptic Soy Broth, respectively, over 48 hours under identical culture conditions. In addition, the formulated medium was able to maintain a large viable cell population for a longer period of time (three days) compared to Tryptic Soy Broth. Thus, preliminary data suggested that the formulated medium holds potential for use as a high cell density aerobic growth medium for Gram-negative bacteria.

scholarly journals Formulation of a semi-defined medium for high cell density cultivation of Escherichia coli in shake flasks

2017 ◽  
Author(s):  
Wenfa Ng ◽  
Yen-Peng Ting
Keyword(s):  
Cell Density ◽  
Yeast Extract ◽  
High Cell Density ◽  
Nitrogen Sources ◽  
Buffer System ◽  
High Cell ◽  
Carbon And Nitrogen Sources ◽  
E Coli ◽  
Carbon And Nitrogen ◽  
Shake Flasks

Microbes for environmental research should be cultured in growth media with characteristics (e.g., pH, ionic strength, and ionic composition) as close to their original habitat as possible. Additionally, the medium should also enable high cell density to be obtained, which is needed for providing sufficient cells in subsequent experiments. This in-progress report describes the formulation of a medium with an environmentally relevant composition (i.e., lack of complex organics), and that allows aerobic high cell density cultivation of Escherichia coli DH5α (ATCC 53868) in shake flasks. The formulated medium comprises four components: a buffer system (K2HPO4: 12.54 g/L and KH2PO4: 2.31 g/L), vitamins (yeast extract: 12.0 g/L), salts (NaCl: 5.0 g/L and MgSO4: 0.24 g/L), and carbon and nitrogen sources (D-Glucose: 6.0 g/L and NH4Cl: 1.5 g/L). Notable characteristics of this medium were: high capacity phosphate buffer system (89 mM phosphate); 1:1 molar ratio between D-Glucose and NH4Cl; and yeast extract providing trace elements and a secondary carbon and nitrogen source. Growth experiments revealed that an OD600nm of 9 was obtained after 24 hours of cultivation at 37 oC. Glucose and NH4Cl served as primary carbon and nitrogen sources for this growth phase. After 48 hours, the OD600nm reached 11, where carbohydrates, lipids and proteins in yeast extract provided the nutrients for biomass formation. Broth’s pH varied between 5.5 and 7.8 during cultivation, which is conducive for E. coli growth. In comparison, the OD600nm of E. coli reached 1.4, 3.2, and 9.2 in three commonly used complex media; Nutrient Broth, LB Lennox, and Tryptic Soy Broth, respectively, over 48 hours under identical culture conditions. In addition, the formulated medium was able to maintain a large viable cell population for a longer period of time (three days) compared to Tryptic Soy Broth. Thus, preliminary data suggested that the formulated medium holds potential for use as a high cell density aerobic growth medium for Gram-negative bacteria.

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