Thermostable glucoamylase

• US 6,255,084 B1
• Filed: 11/24/1998
• Issued: 07/03/2001
• Est. Priority Date: 11/26/1997
• Status: Expired due to Term

• Current Assignee: Novozymes A/S (Novozymes)
• Original Assignee: Novozymes A/S (Novozymes)
• Inventors: Nielsen, Bjarne Rønfeldt, Lehmbeck, Jan, Nielsen, Ruby Ilum
• Primary Examiner(s): Prouty, Rebecca E.
• Application Number:
  US09/199,290
• Time in Patent Office: 952 Days
• Field of Search: 435/205, 435/96, 435/254.1
• US Class Current: 435/96
• CPC Class Codes: C12N 1/145 Fungal isolates
• CPC Class Codes: C12N 9/2428 Glucan 1,4-alpha-glucosidase (3.2.1.3), i.e. glucoamylase
• CPC Class Codes: C12P 19/20 produced by the action of an exo-1,4 alpha-glucosidase, e.g. dextrose
• CPC Class Codes: C12R 2001/645 Fungi ; Processes using fungi

Abstract

The invention relates to an isolated thermostable glucoamylase derived from Talaromyces emersonii suitable for starch conversion processes.

Claims

1. An isolated enzyme with glucoamylase activity, wherein the enzyme (a) is derived from Talaromyces and has a T_½

(half-life) of at least 100 minutes in 50 mM NaOAc, 0.2 Novo Amyloglucosidase Unit (AGU)/ml, pH 4.5, at 70°

C. or (b) has an amino acid sequence that has at least 80% identity with the glucoamylase of SEQ ID NO;

7.

2. The enzyme of claim 1, wherein the enzyme is derived from Talaromyces and has a T_½

(half-life) of at least 100 minutes in 50 mM NaOAc, 0.2 Novo Amyloglucosidase Unit (AGU)/ml, pH 4.5, at 70°

C.

3. The enzyme of claim 1, wherein the enzyme has an amino acid sequence that is at least 80% identical with the glucoamylase of SEQ ID NO:

7.

4. The enzyme of claim 3, wherein the enzyme has an amino acid sequence that is at least 90% identical with the glucoamylase of SEQ ID NO:

7.

5. The enzyme of claim 4, wherein the enzyme has an amino acid sequence that is at least 95% identical with the glucoamylase of SEQ ID NO:

7.

6. The enzyme of claim 5, wherein the enzyme has an amino acid sequence that is at least 97% identical with the glucoamylase of SEQ ID NO:

7.

7. The enzyme of claim 6, wherein the enzyme has an amino acid sequence that is at least 99% identical with the glucoamylase of SEQ ID NO:

7.

8. The enzyme of claim 1 which has a molecular weight of about 70 kDa determined by SDS-PAGE.

9. The enzyme of claim 1 which has an isoelectric point below 3.5 determined by isoelectric focusing.

10. The enzyme of claim 1 which is derived from a fungal organism.

11. The enzyme of claim 10 which is derived from a filamentous fungus.

12. The enzyme of claim 11, wherein the filamentous fungus is a Talaromyces strain.

13. The enzyme of claim 12, wherein the filamentous fungus is a Talaromyces emersonii strain.

14. The enzyme of claim 13, wherein the filamentous fungus is Talaromyces emersonii CBS 793.97.

19. A process for converting starch or partially hydrolyzed starch into a syrup containing dextrose, comprising saccharifying a starch hydrolyzate in the presence of an enzyme of claim 1.

20. The process of claim 19, wherein the dosage of the enzyme is in the range from 0.05 to 0.5 AGU per gram of dry solids.

21. The process of claim 19, wherein the starch hydrolyzate has at least 30 percent by weight of dry solids.

22. The process of claim 19, wherein the saccharification is performed in the presence of a debranching enzyme selected from the group of pullulanase and isoamylase.

23. The process of claim 19, wherein the saccharification is performed at a pH of about 3 to 5.5, a temperature of 60-80°

C., and for 24 to 72 hours.

24. A method of saccharifying a liquefied starch solution, comprising applying an enzyme of claim 1 to the liquefied starch solution.

15. An isolated enzyme having an amino acid sequence comprising amino acids 28-618 of SEQ ID NO:

34.

16. The enzyme of claim 15 having an amino acid sequence consisting of amino acids 28-618 of SEQ ID NO:

34.

17. The enzyme of claim 16 having an amino acid sequence comprising amino acids 1-618 of SEQ ID NO:

34.

18. An isolated enzyme having an amino acid sequence comprising amino acids 28-618 of SEQ ID NO:

34 and the substitution of Asp at position 145 with Asn.