Method for producing poly(3-hydroxyalkanoate)
In culturing a poly(3-hydroxyalkanoate)-producing microorganism, an oil A and an oil B are used as the carbon source. The proportion of the oil B to the total amount of the oils A and B used during the entire course of the culturing is 10 wt % or more. The oil A is the total oil used until the amount of the poly(3-hydroxyalkanoate) accumulated in the poly(3-hydroxyalkanoate)-producing microorganism reaches 16 wt %, and the average unsaturated fatty acid content in constituent fatty acids is from 25 wt % to less than 75 wt % in the total oil A. The unsaturated fatty acid content in constituent fatty acids in the oil B is higher than the average unsaturated fatty acid content in the total oil A.
1 . A method comprising:
culturing a poly(3-hydroxyalkanoate)-producing microorganism in the presence of a carbon source comprising oil, wherein the poly(3-hydroxyalkanoate)-producing microorganism is Cupriavidus necator and wherein the culturing comprises:
adding an oil A until an amount of poly(3-hydroxyalkanoate) accumulated in the poly(3-hydroxyalkanoate)-producing microorganism reaches at least 16 wt %, and an average unsaturated fatty acid content in constituent fatty acids is from 25 wt % to less than 75 wt % in the oil A;
stopping adding the oil A; and
adding an oil B such that a proportion of oil B to oils A and B added during an entire course of the culturing is 10 wt % or more;
wherein the amount of the poly(3-hydroxyalkanoate) accumulated in the poly(3-hydroxyalkanoate)-producing microorganism is a percentage of a weight of the poly(3-hydroxyalkanoate) collected from a given amount of culture fluid compared to a weight of dried microbial cells obtained from the given amount of culture fluid, and
an unsaturated fatty acid content in constituent fatty acids in the oil B is higher than the average unsaturated fatty acid content in the oil A.
2 . The method according to claim 1 , wherein the oil B is added after a time point at which an amount of the poly(3-hydroxyalkanoate) accumulated in the microorganism is more than 16 wt % and less than 85 wt %.
3 . The method according to claim 1 , wherein the oil B is an oil in which the unsaturated fatty acid content is from 60 to 98 wt %.
4 . The method according to claim 1 , wherein the proportion of oil B to oils A and B added during the entire course of the culturing is 40 wt % or more.
5 . The method according to claim 1 , wherein the culturing of the poly(3-hydroxyalkanoate)-producing microorganism is performed until the amount of the poly(3-hydroxyalkanoate) accumulated in the poly(3-hydroxyalkanoate)-producing-microorganism reaches 80 wt % or more.
6 . The method according to claim 1 , wherein the culturing of the poly(3-hydroxyalkanoate)-producing microorganism is performed with consecutive addition of the oil A and/or the oil B to a culture medium containing the poly(3-hydroxyalkanoate)-producing microorganism.
7 . The method according to claim 1 , wherein the culturing of the poly(3-hydroxyalkanoate)-producing microorganism is first performed with consecutive addition of the oil A to a culture medium containing the poly(3-hydroxyalkanoate)-producing microorganism and is then continued with consecutive addition of the oil B to the culture medium.
8 . The method according to claim 1 , wherein the poly(3-hydroxyalkanoate) comprises 3-hydroxybutyrate units.
9 . The method according to claim 1 , wherein the poly(3-hydroxyalkanoate) comprises a homopolymer of 3-hydroxybutyrate units or a copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units.
10 . The method according to claim 9 , wherein the other hydroxyalkanoate units are 3-hydroxyhexanoate units.