Microalgal biomass protein enrichment method

Abstract

The invention relates to a method for protein enrichment of a microalga grown under heterotrophic conditions, said microalga being of the Chlorella genus, characterized in that the heterotrophic culture comprises a step aimed at limiting the growth of said microalga by means of a deficiency of the fermentation medium in terms of a non-nitrogenous nutritional source.

1 - 8 . (canceled) 
     
     
         9 . A method of protein enrichment of a microalga grown heterotrophically, said microalga being of the genus  Chlorella , comprising a step of limiting the growth of said microalga by means of a deficiency in the fermentation medium of a non-nitrogenous nutritional source, thus making it possible for the biomass protein content to reach more than 50% by weight. 
     
     
         10 . The method of  claim 9 , wherein the deficient non-nitrogenous nutritional source is selected from the group consisting of glucose and phosphates. 
     
     
         11 . The method of  claim 10 , wherein the non-nitrogenous nutritional source is deficient so as to obtain a growth rate that is 10% to 60% lower than the growth rate without the limiting of said non-nitrogenous nutritional source. 
     
     
         12 . The method of  claim 11 , wherein the microalgae of the genus  Chlorella  are selected from the group consisting of  Chlorella sorokiniana  and  Chlorella protothecoides.    
     
     
         13 . The method of  claim 12 , wherein said microalgae are supplied with a nutritive substance so as to obtain a growth rate of between 0.06 h −1  and 0.09 h −1 . 
     
     
         14 . The method of  claim 9 , wherein the duration of the deficient culturing phase is at least 1 h. 
     
     
         15 . The method of  claim 9 , wherein the duration of the deficient culturing phase is at least 10 h. 
     
     
         16 . The method of  claim 9 , wherein the duration of the deficient culturing phase is at least 20 h. 
     
     
         17 . The method of  claim 9 , wherein the duration of the deficient culturing phase is between 30 h and 60 h. 
     
     
         18 . The method of  claim 12 , wherein the heterotrophic culturing of microalgae of the species  Chlorella sorokiniana  comprises:
 a) a first step in which the microalgae are grown and the glucose supply rate is adjusted to the consumption capacity of said microalgae so as to obtain a large biomass quickly, and   b) a second step in which the microalgae produce proteins, where the glucose supply rate is set to a value distinctly below the glucose consumption capacity of said microalgae so as to prevent the additional accumulation of storage substances or to promote their consumption.   
     
     
         19 . The method of  claim 12 , wherein the heterotrophic culturing of microalgae of the species  Chlorella protothecoides  comprises a step of culturing with a phosphate deficiency that limits the growth rate and results in an increase in the protein content.