Process for the aerobic cultivation of microorganisms

Claim 2

The process of claim 1 further characterized in that the pH of the fermentation mass is controlled by the addition of an alkaline material selected from the group consisting of sodium hydroxide, ammonium hydroxide and ammonia.

Claim 3

The process of claim 1 further characterized in that water is also introduced into the fermentation vessel in an amount equivalent to the amount of water removed by evaporation during the evaporative cooling of the fermentation mass.

Claim 4

The process of claim 1 further characterized in that the portion of the fermentation mass withdrawn from the fermentation vessel prior to recovering the microorganism therefrom is matured in a second fermentation vessel at a temperature below that which is employed in the first fermentation vessel in the presence of an aqueous nutrient medium and a gas containing free oxygen in the absence of added assimilable carbon source.

Claim 5

A process for the aerobic cultivation of a hydrocarbon-consuming microorganism which comprises introducing an aqueous nutrient medium, a hydrocarbon and a viable culture of a hydrocarbon-consuming microorganism into a fermentation vessel having an L/D of about one-half to about one-twentieth where L is the height of said vessel and D is the length of one side of said vessel having a square cross-sectional configuration or the diameter of said vessel having a circular cross-sectional configuration, said vessel containing at least one draft tube, the amount of said viable culture in said vessel comprising about 0.1 to about 3 grams of microorganism (dry basis) per liter of liquid in said vessel; introducing gas containing free oxygen into the lower portion of the fermentation mass thus formed in said vessel, said gas being introduced in an amount sufficient to effect (1) growth of said microorganism, (2) agitation of said fermentation mass and (3) removal of the heat of fermentation by evaporation of water from the fermentation mass; continuing the cultivation of the hydrocarbon-consuming microorganism in the growth-supporting mixture of aqueous nutrient medium, hydrocarbon and gas containing free oxygen until the cell concentration of the microorganism in the fermentation mass reaches a maximum under logarithmic growth, said maximum cell concentration being about 5 to about 25 grams per liter of fermentation mass; and thereafter harvesting the cells.

Claim 6

A process for the aerobic cultivation of a hydrocarbon-consuming microorganism which comprises introducing an aqueous nutrient medium, a hydrocarbon and a viable culture of a hydrocarbon-consuming microorganism into a fermentation vessel having an L/D of about one-half to about one-twentieth where L is the height of said vessel and D is the length of one side of said vessel having a square cross-sectional configuration or the diameter of said vessel having a circular cross-sectional configuration, said vessel containing at least one draft tube, the amount of said viable culture in said vessel comprising about 0.1 to about 3 grams of microorganism (dry basis) per liter of liquid in said vessel; introducing gas containing free oxygen into the lower portion of the fermentation mass thus formed in said vessel, said gas being introduced in an amount sufficient to efFect (1) growth of said microorganism, (2) agitation of said fermentation mass and (3) removal of the heat of fermentation by evaporation of water from the fermentation mass; continuing the cultivation of the hydrocarbon-consuming microorganism in the growth-supporting mixture of aqueous nutrient medium, hydrocarbon and gas containing free oxygen until the cell concentration of the microorganism in the fermentation mass reaches a maximum under logarithmic growth, said maximum cell concentration being about 5 to about 25 grams per liter of fermentation mass; thereafter propagating the hydrocarbon-consuming microorganism in said fermentation vessel by continuously introducing into the ferementation mass in said vessel aqueous nutrient medium, hydrocarbon and gas containing free oxygen, the amount of said gas being sufficient to effect (1) growth of said microorganism, (2) agitation of said fermentation mass and (3) removal of the heat of fermentation by evaporation of water from the fermentation mass; withdrawing a portion of the fermentation mass from the fermentation vessel, the portion which is withdrawn being equal to the volume of aqueous nutrient medium and hydrocarbon which is introduced into the fermentation vessel; and recovering the microorganism from the fermentation mass thus withdrawn.

Claim 7

A process for the aerobic cultivation of a hydrocarbon-consuming yeast which comprises introducing an aqueous nutrient medium, a hydrocarbon and a viable culture of a hydrocarbon-consuming yeast at an active fermentation temperature of about 20* to about 40* C. into a fermentation vessel having an L/D of about one-half to about one-twentieth where L is the height of said vessel and D is the length of one said vessel having a square cross-sectional configuration or the diameter of said vessel having a circular cross-sectional configuration, said vessel containing at least one draft tube, the amount of said viable culture in said vessel comprising about 0.1 to about 3 grams of yeast per liter of liquid in said vessel; introducing gas containing free oxygen into the lower portion of the fermentation mass thus formed in said vessel, said gas being introduced in an amount sufficient to effect (1) growth of said yeast, (2) agitation of said fermentation mass and (3) removal of the heat of fermentation by evaporation of water from the fermentation mass; continuing the cultivation of the hydrocarbon-consuming yeast in the growth-supporting mixture of aqueous nutrient medium, hydrocarbon and gas containing free oxygen until the cell concentration of the yeast in the fermentation mass reaches a maximum under logarithmic growth, said maximum cell concentration being about 5 to about 25 grams per liter of fermentation mass; thereafter progagating the hydrocarbon-consuming yeast in said fermentation vessel by continuously introducing into the fermentation mass in said vessel aqueous nutrient medium, hydrocarbon and gas containing free oxygen, the amount of said gas being sufficient to effect (1) growth of said yeast, (2) agitation of said fermentation mass and (3) removal of the heat of fermentation by evaporation of water from the fermentation mass; withdrawing a portion of the fermentation mass from the fermentation vessel, the portion which is withdrawn being equal to the volume of aqueous nutrient medium and hydrocarbon which is introduced into the fermentation vessel; and recovering the yeast from the fermentation mass thus withdrawn.

Claim 8

The process of claim 8 wherein the yeast is of the family Cryptoccaceae.

Claim 9

The process of claim 8 wherein the yeast is of the subfamily Cryptococcoideae.

Claim 10

The process of claim 8 wherein the yeast is of the genus Candida.

Claim 11

The process of claim 8 wherein the yeast is of the strain Candida tropicalis.

Claim 12

The process of claim 8 wherein the yeast is Candida tropicalis, CS-9-5.

Claim 13

The process of claim 8 wherein the hydrocarbon is a liquid petroleum fraction consisting essentially of a mixture of straight chain hydrocarbons.

Claim 14

The process of claim 14 wherein the liquid petroleum fraction is a mixture of C13 to C18 normal paraffins.

Claim 15

The process of claim 8 wherein the pH of the fermentation mass is within the range of about 1.5 to about 8.

Claim 16

The process of claim 8 wherein the oxygen-containing gas is air.

Claim 17

A process for the aerobic cultivation of a hydrocarbon-consuming yeast of the strain Candida tropicalis which comprises introducing an aqueous nutrient medium, a hydrocarbon feedstock comprising a mixture of C13 to C18 normal paraffins and a viable culture of the Candida tropicalis at a temperature of about 25* to about 35* C. into a square fermentation vessel having an L/D of about 1/5.3 where L is the height of said vessel and D is the length of one side of said vessel, said vessel containing at least 4 draft tubes; introducing air into the lower portion of the fermentation mass thus formed in said vessel, said air being introduced in an amount sufficient to effect (1) growth of said Candida tropicalis, (2) agitation of said fermentation mass and (3) removal of the heat of fermentation by evaporation of water from the fermentation mass; continuing the cultivation of the Candida tropicalis in the growth-supporting mixture of aqueous nutrient medium, hydrocarbon feedstock comprising a mixture of C13 to C18 normal paraffins and air until the cell concentration of the Candida tropicalis in the fermentation mass reaches a maximum under logarithmic growth, said maximum cell concentration of the Candida tropicalis being about 5 to about 25 grams per liter of fermentation mass; thereafter propagating the Candida tropicalis at a cell concentration of about 5 to about 25 grams per liter in said fermentation vessel by continuously introducing into the fermentation mass in said vessel aqueous nutrient medium, hydrocarbon feedstock comprising a mixture of C13 to C18 normal paraffins and air, the amount of said air being sufficient to effect (1) growth of said Candida tropicalis (2) agitation of said fermentation mass and (3) removal of the heat of fermentation by evaporation of water from the fermentation mass; withdrawing a portion of the fermentation mass from the fermentation vessel, the portion which is withdrawn being equal to the volume of aqueous nutrient medium and hydrocarbon feedstock which is introduced into the fermentation vessel; and recovering the Candida tropicalis from the fermentation mass thus withdrawn.

Claim 18

The process of claim 18 wherein the number of draft tubes is 9.

Claim 19

The process of claim 18 further characterized in that the pH of the fermentation mass is controlled within the range of about 2.5 to about 5 by the addition of ammonia.

Claim 20

The process of claim 20 further characterized in that the water is also introduced into the fermentation vessel in an amount equivalent to the amount of water removed by evaporation during the evaporative cooling of the fermentation mass.

Claim 21

The process of claim 21 further characterized in that the portion of the fermentation mass withdrawn from the fermentation vessel prior to recovering Candida tropicalis therefrom is matured in a second fermentation vessel at a temperature of about 10* to about 20* C. in the presence of aqueous nutrient medium and air in the absence of added hydrocarbon.

Claim 22

The process of claim 22 wherein the Candida tropicalis is Candida tropicalis, CS-9-5.