Glucoamylase variants and polynucleotides encoding same
The present invention relates to glucoamylase variants having improved thermostability and compositions comprising such variants. The present invention further relates to polynucleotides encoding such variants, vectors and host cells comprising genes encoding such variants, which may also enable the production of such variants. The present invention also relates to methods of liquefying starch-containing materials using or applying the variants or compositions, as well as the saccharification thus produced by the method. The present invention also relates to methods of saccharifying starch-containing materials using or applying the variants or compositions, as well as the saccharides thus produced by the method. The present invention further relates to processes for producing fermentation products from starch-containing or cellulosic-containing material, as well as an enzyme blend or composition, or a recombinant host cell or fermenting organism suitable for use in processes of the invention.
1 . A glucoamylase variant having improved thermostability, comprising a substitution at one or more positions corresponding to positions: 50, 484, and 539 of SEQ ID NO: 1, wherein the substitution at position 50 is to an arginine, and wherein said variant has at least 80% but less than 100% sequence identity to the polypeptide of SEQ ID NOs: 1, 4, or 6.
2 . The glucoamylase variant according to claim 1 , wherein the variant further comprises a substitution in one or more positions corresponding to positions 11, 75, 77, 78, 79, 80, 103, 105, 107, 110, 135, 138, 379, 445, 504, 566, 594 of SEQ ID NO: 1.
3 . The glucoamylase variant according to claim 1 , wherein the variant further comprises a substitution at one or more positions corresponding to positions: 6, 7, 11, 31, 34, 75, 77, 78, 79, 80, 103, 105, 107, 110, 132, 135, 138, 379, 445, 447, 501, 504, 566, 568 592, 594, of SEQ ID NO: 1; and wherein said variant has at least 80% but less than 100% sequence identity to the polypeptide of SEQ ID NOs: 1, 4, or 6.
4 . The glucoamylase variant according to claim 1 , wherein said improved thermostability as measured by a Thermal Shift Assay (TSA) as increased melting temperature of at least 0.1° C., at least 0.2° C., at least 0.3° C., at least 0.4° C., at least 0.5° C., at least 0.6° C., at least 0.7° C., at least 0.8° C., at least 0.9° C., at least 1° C., at least 1.5° C., at least 2° C., at least 2.5° C., at least 3° C., at least 3.5° C., at least 4.0° C., at least 4.5° C. or of at least 1° C., at least 1.5° C., at least 2° C., at least 2.5° C., at least 3° C., at least 3.5° C., at least 4.0° C., at least 4.5° C. or at least 5° C. or at least 5.5° C. or at least 6° C. or at least 6.5° C. or at least 7° C. or at least 7.5° C. or at least 8° C. or at least 8.5° C. or at least 9° C. or at least 9.5° C. or at least 10° C. compared to said parent glucoamylase.
5 . The glucoamylase variant according to claim 1 , wherein variant have a relative activity at 91° C. of at least 150 compared to said parent glucoamylase.
6 . The glucoamylase variant according to claim 1 , wherein said further variant comprises one or more of the following substitutions at positions corresponding to positions: G6S, G7T, P11F, R31F, K34Y, D75N, D75S, R77D, R77G, A78Q, A78W, V79D, F80Y, S103N, S105E, S105L, P107L, T110W, A132P, A132R, R135S, R138G, R138L, R138P, S379P, D445N, V447S, S481P, E501A, E501L, E501V, Y504T, D566T, T568V, V592T, Q594R, F595S of SEQ ID NO: 1 and wherein said variant has at least 80% but less than 100% sequence identity to the polypeptide of SEQ ID NOs: 1, 4, or 6.
7 . The variant according to claim 1 , wherein the variant comprises at least one of the following substitutions or combinations of substitutions:
G6S+G7T+K34Y+E50R+S103N+P107L+A132P+D445N+V447S+Y504T+D566T+T568V+Q594R+F595S;
G6S+G7T+K34Y+E50R+S103N+P107L+A132P+D445N+V447S+S481P+Y504T+D566T+T568V+Q594R+F595S;
G6S+G7T+K34Y+E50R+S103N+A132P+D445N+V447S+S481P+D566T+T568V+Q594R+F595S;
G6S+G7T+R31F+K34Y+E50R+S103N+A132P+D445N+V447S+S481P+D566T+T568V+Q594R+F595S;
K34Y+E50R+D75N+R77D+A78Q+S103N+R138L+D445N+V447S+Q594R+F595S;
G6S+G7T+R31F+K34Y+E50R+D75N+R77D+A78Q+S103N+A132P+D445N+V447S+S481P+D566T+Q594R+F595S;
R31F+K34Y+E50R+D75N+R77D+A78Q+S103N+R138L+D445N+V447S+Q594R+F595S;
G6S+G7T+R31F+K34Y+E50R+D75N+R77D+A78Q+S103N+A132P+R138L+D445N+V447S+S481P+D566T+Q594R+F595S;
R135S;
G6S+G7T+R31F+K34Y+E50R+S103N+A132P+D445N+V447S+S481P+E501L+D566T+T568V+Q594R+F595S;
G6S+G7T+R31F+K34Y+E50R+S103N+A132P+S379P+D445N+V447S+S481P+E501A+D566T+T568V+Q594R+F595S;
G6S+G7T+R31F+K34Y+E50R+S103N+A132P+D445N+V447S+S481P+T484P+E501A+D566T+T568V+Q594R+F595S;
G6S+G7T+R31F+K34Y+E50R+S103N+A132P+D445N+V447S+S481P+E501A+N539P+D566T+T568V+Q594R+F595S;
G6S+G7T+R31F+K34Y+E50R+S103N+A132P+S379P+D445N+V447S+S481P+T484P+E501A+D566T+T568V+Q594R+F595S;
G6S+G7T+R31F+K34Y+E50R+S103N+A132P+D445N+V447S+S481P+T484P+E501A+N539P+D566T+T568V+Q594R+F595S of SEQ ID NO: 1 and, wherein the variant has glucoamylase activity and wherein said variant has at least 80% but less than 100% sequence identity to the polypeptide of SEQ ID NOs: 1, 4, or 6.
8 . A polynucleotide or a nucleic acid construct or expression vector comprising glucoamylase variant of claim 1 , wherein the polynucleotide is operably linked to one or more control sequences that direct the production of the polypeptide in an expression host.
9 . A method of producing a glucoamylase variant of claim 1 , comprising cultivating the recombinant host cell under conditions conducive for production of the variant and recovering the variant.
10 . A composition comprising the variant of claim 1 and one or more additional enzymes.
11 . A process of producing a fermentation product from starch-containing material comprising the steps of:
(a) liquefying starch-containing material in the presence of an alpha amylase;
(b) saccharifying the liquefied material; and
(c) fermenting with a fermenting organism;
wherein step (a), step (b), and/or step (c) is carried out using at least a glucoamylase variant of claim 1 .
12 . A process of producing a fermentation product from starch-containing material, comprising the steps of:
(a) saccharifying starch-containing material at a temperature below the initial gelatinization temperature of said starch-containing material; and
(b) fermenting with a fermenting organism, wherein step (a) and/or step (b) is carried out using at least a glucoamylase variant of claim 1 .
13 . A process for producing a fermentation product from a cellulosic-containing material comprising:
(a) pretreating a cellulosic-containing material;
(b) saccharifying a cellulosic-containing material and/or pretreated cellulosic-containing material using a carbohydrate-source generating enzyme; and
(c) fermenting using a fermenting organism;
(d) wherein at least one or more glucoamylase variant(s) of claim 1 is present or added during saccharifying step (b) and/or fermenting step c).
14 . The glucoamylase variant according to claim 1 , wherein said variant comprises one or more of the following substitutions at positions corresponding to positions: T484P, and N539P of SEQ ID NO: 1 and wherein said variant has at least 80% but less than 100% sequence identity to the polypeptide of SEQ ID NOs: 1, 4, or 6.
15 . The variant according to claim 1 , wherein the variant has at least 85% but less than 100% sequence identity to the polypeptide of SEQ ID NOs: 1, 4, or 6.
16 . The variant according to claim 1 , wherein the variant has at least 90% but less than 100% sequence identity to the polypeptide of SEQ ID NOs: 1, 4, or 6.