Expression of processed recombinant lactoferrin and lactoferrin polypeptide fragments from a fusion product in Aspergillus

• US 5,571,697 A
• Filed: 11/02/1994
• Issued: 11/05/1996
• Est. Priority Date: 05/05/1989
• Status: Expired due to Term

• Current Assignee: Agennix, Inc. (Agennix AG)
• Original Assignee: Baylor College of Medicine (Baylor College)
• Inventors: Headon, Denis R., O'Malley, Bert W., Conneely, Orla M.
• Primary Examiner(s): Wax, Robert A.
• Assistant Examiner(s): Moore, William W.
• Application Number:
  US08/303,009
• Time in Patent Office: 734 Days
• Field of Search: 424/439, 514/6, 435/69.7, 435/172.3, 435/252.3, 435/254.11, 435/254.21, 435/254.23, 435/254.3, 435/320.1, 530/350, 530/400, 530/412, 530/300, 530/395, 536/23.4, 536/23.5, 536/23.74, 536/24.1
• US Class Current: 435/69.7
• CPC Class Codes: A61K 38/00 Medicinal preparations containing peptides peptides containing beta-lactam rings A61K31/00; cyclic dipeptides not having in their molecule any other peptide link than those which form their ring, e.g. piperazine-2,5-diones, A61K31/00; ergot alkaloids of the cyclic peptide type A61K31/48; containing macromolecular compounds having statistically distributed amino acid units A61K31/74; medicinal preparations containing antigens or antibodies A61K39/00; medicinal preparations characterised by the non-active ingredients, e.g. peptides as drug carriers, A61K47/00
• CPC Class Codes: C07K 14/79 Transferrins, e.g. lactoferrins, ovotransferrins
• CPC Class Codes: C07K 2319/02 containing a signal sequence
• CPC Class Codes: C12N 15/80 for fungi

Abstract

The subject invention provides for the production of lactoferrins and lactoferrin polypeptide fragments using the host cells Aspergillus in combination with novel plasmid constructs. More specifically, the subject invention provides novel vector constructs capable of producing lactoferrins and lactoferrin polypeptide fragments in Aspergillus host cells. More particularly, the subject invention provides for novel plasmid constructs suitable for use with Aspergillus and especially Aspergillus awamori, niger and oryzae host cells, which enables them to produce large amounts of recombinant lactoferrins and lactoferrin polypeptide fragments.

Claims

1. A plasmid DNA sequence comprising nucleotide sequence elements operably linked in the following 5'"'"' to 3'"'"' order:

(a) a fungal promoter sequence;

(b) a sequence encoding a signal peptide;

(c) a sequence encoding an amino terminal portion of a highly expressed endogenous gene the product of which is secreted by Aspergillus cells; and

,

(d) a sequence selected from the group consisting of a nucleotide sequence encoding a mature, native, lactoferrin, a nucleotide sequence encoding an iron-binding lobe of a native lactoferrin and a nucleotide sequence encoding an antimicrobial peptide of a native lactoferrin.

2. The plasmid DNA sequence of claim 1, wherein the promoter is selected from genes of the group consisting of an alcohol dehydrogenase gene, an α

-amylase gene, a glucoamylase gene, and a benA gene.

3. The plasmid DNA sequence of claim 2, wherein said promoter is a glucoamylase gene promoter.

4. The plasmid DNA sequence of claim 3, wherein the glucoamylase gene is endogenous to A. awamori or A. niger.

5. The plasmid DNA sequence of claim 2, wherein the promoter is an α

-amylase gene promoter.

6. The plasmid DNA sequence of claim 5, wherein the α

-amylase gene is endogenous to A. oryzae.

7. The plasmid DNA sequence of claim 1, wherein the signal peptide-encoding sequence is selected from the genes of the group consisting of a glucoamylase gene and an α

-amylase gene.

8. The plasmid DNA sequence of claim 7, wherein the signal peptide-encoding sequence is an A. awamori glucoamylase gene or an A. niger glucoamylase gene.

9. The plasmid DNA sequence of claim 7, wherein the signal peptide-encoding sequence is selected from an A. oryzae α

-amylase gene.

10. The plasmid DNA sequence of claim 1, wherein the sequence encoding an amino terminal portion of an endogenous, secreted, Aspergillus polypeptide is selected from the group of Aspergillus genes consisting of an α

-amylase gene and a glucoamylase gene.

11. The plasmid DNA sequence of claim 10, wherein the endogenous Aspergillus gene is an A. oryzae α

-amylase gene.

12. The plasmid DNA sequence of claim 10, wherein the endogenous Aspergillus gene is an A. awamori glucoamylase gene or an A. niger glucoamylase gene.

13. The plasmid DNA sequence of claim 1, wherein the native lactoferrin is selected from the group consisting of a human lactoferrin, a bovine lactoferrin and a porcine lactoferrin.

14. The plasmid DNA sequence of claim 1, further comprising a transcription termination sequence and a selectable marker gene.

15. The plasmid DNA sequence of claim 14, wherein the transcription termination sequence is selected from a gene of the group consisting of an α

-amylase gene, a glucoamylase gene, an alcohol dehydrogenase gene and a benA gene.

16. The plasmid DNA sequence of claim 15, wherein the transcription termination sequence is from an A. niger glucoamylase gene.

17. The plasmid DNA sequence of claim 14, wherein the selectable marker gene is selected from the genes of the group consisting of a pyr4 gene, a pyrG gene, an amdS gene, an argB gene, a trpC gene, and a phleomycin resistance gene.

18. The plasmid DNA sequence of claim 17, wherein the selectable marker is the phleomycin resistance gene.

19. The plasmid DNA sequence of claim 1, further comprising a sequence encoding a peptide linker joining an amino terminal portion of said encoded endogenous Aspergillus polypeptide to the amino terminus of an encoded native lactoferrin polypeptide, iron-binding lobe of a native lactoferrin, or an antimicrobial peptide of a native lactoferrin, the peptide linker comprising a fungal peptidase cleavage site.

20. The plasmid DNA sequence of claim 19, wherein the linker peptide encoding sequence comprises codons encoding the Kex2 peptidase cleavage site.

21. The plasmid DNA sequence of claim 19, wherein the promoter is selected from genes of the group consisting of an alcohol dehydrogenase gene, an α

-amylase gene, a glucoamylase gene, and a benA gene.

22. The plasmid DNA sequence of claim 21, wherein the promoter is a glucoamylase gene promoter.

23. The plasmid DNA sequence of claim 22, wherein the glucoamylase gene is an A. awamori glucoamylase gene or an A. niger glucoamylase gene.

24. The plasmid DNA sequence of claim 21, wherein the promoter is an α

-amylase gene promoter.

25. The plasmid DNA sequence of claim 24, wherein the α

-amylase gene is an A. oryzae α

-amylase gene.

26. The plasmid DNA sequence of claim 19, wherein the signal peptide-encoding sequence is selected from the genes of the group consisting of a glucoamylase gene and an α

-amylase gene.

27. The plasmid DNA sequence of claim 26, wherein the signal peptide encoding sequence is selected from an A. awamori glucoamylase gene or an A. niger glucoamylase gene.

28. The plasmid DNA sequence of claim 26, wherein the signal peptide-encoding sequence is selected from an A. oryzae α

-amylase gene.

59. A mature, native, lactoferrin, an iron-binding lobe of a native lactoferrin, or an antimicrobial peptide of a native lactoferrin produced when the plasmid DNA sequence of claim 1, is transformed into an Aspergillus fungal cell, and the transformed Aspergillus fungal cell is grown under conditions suitable for expression of the mature, native, lactoferrin, the iron-binding lobe of a native lactoferrin, or the antimicrobial peptide of a native lactoferrin.

60. An antimicrobial peptide of a native lactoferrin produced when the plasmid DNA sequence of claim 1 is transformed into an Aspergillus fungal cell and the transformed Aspergillus fungal cell is grown under conditions suitable for expression of the antimicrobial peptide of a native lactoferrin, wherein said antimicrobial peptide comprises an iron-binding domain.

61. A mature, native, lactoferrin, an iron binding lobe of a native lactoferrin polypeptide, or an antimicrobial peptide of a native lactoferrin produced when the plasmid DNA sequence of claim 19, is used to transform an Aspergillus fungal cell, and the transformed Aspergillus fungal cell is grown under conditions suitable for expression of the lactoferrin.

62. An antimicrobial peptide of a native lactoferrin produced when the plasmid DNA sequence of claim 19 is transformed into an Aspergillus fungal cell, and the transformed Aspergillus fungal cell is grown under conditions suitable for expression of the antimicrobial peptide of a native lactoferrin, wherein said antimicrobial peptide comprises an iron-binding domain.

29. A plasmid DNA sequence comprising the following components operably linked from 5'"'"' to 3'"'"':

(a) a promoter from A. niger glucoamylase gene;

(b) a signal peptide-encoding sequence from the A. niger glucoamylase gene;

(c) a sequence encoding an amino terminal portion of the A. niger glucoamylase gene;

(d) a sequence encoding a peptide linker comprising a Kex2 peptidase cleavage site whereby there is an endogenous proteolytic enzyme specific for said linker sequence;

(e) a nucleotide sequence selected from the group consisting of a nucleotide sequence encoding a mature, native, lactoferrin, a nucleotide sequence encoding an iron-binding lobe of a native lactoferrin and a nucleotide sequence encoding an antimicrobial peptide of a native lactoferrin;

(f) a transcription termination sequence from the A. niger glucoamylase gene; and

(g) a phleomycin resistance selectable marker gene.

30. A plasmid DNA sequence comprising the following components operably linked from 5'"'"' to 3'"'"':

(a) a promoter from A. oryzae α

-amylase gene;

(b) a signal peptide-encoding sequence from the A. oryzae α

-amylase gene;

(c) a sequence encoding an amino terminal portion of the A. oryzae α

-amylase gene;

(d) a sequence encoding a peptide linker comprising a Kex2 peptidase cleavage site whereby there is an endogenous proteolytic enzyme specific for said linker sequence;

(e) a nucleotide sequence selected from the group consisting of a nucleotide sequence encoding a mature, native, lactoferrin, a nucleotide sequence encoding an iron-binding lobe of a native lactoferrin and a nucleotide sequence encoding an antimicrobial peptide of a native lactoferrin;

(f) a transcription termination sequence from the A. niger glucoamylase gene; and

(g) a phleomycin resistance selectable marker gene.

65. A mature, native, lactoferrin, an iron binding lobe of a native lactoferrin polypeptide, or an antimicrobial peptide of a native lactoferrin produced and processed when the vector of claim 30 is used to transform an A. oryzae fungal cell, and the transformed A. oryzae fungal cell is grown under conditions suitable for expression of the lactoferrin.

66. An antimicrobial peptide of a native lactoferrin produced when the plasmid DNA sequence of claim 30 is transformed into an Aspergillus oryzae fungal cell, and the transformed Aspergillus oryzae fungal cell is grown under conditions suitable for expression of the antimicrobial peptide of a native lactoferrin, wherein said antimicrobial peptide comprises an iron-binding domain.

31. A plasmid DNA sequence comprising the following components operably linked from 5'"'"' to 3'"'"':

(a) a promoter from A. awamori glucoamylase gene;

(b) a signal peptide-encoding sequence from the A. awamori glucoamylase gene;

(c) a sequence encoding an amino terminal portion of the A. awamori glucoamylase gene;

(d) a sequence encoding a peptide linker comprising a Kex2 peptidase cleavage site whereby there is an endogenous proteolytic enzyme specific for said linker sequence;

(e) a nucleotide sequence selected from the group consisting of a nucleotide sequence encoding a mature, native, lactoferrin, a nucleotide sequence encoding an iron-binding lobe of a native lactoferrin and a nucleotide sequence encoding an antimicrobial peptide of a native lactoferrin;

(f) a transcription termination sequence from the A. niger glucoamylase gene; and

(g) a phleomycin resistance selectable marker gene.

32. The plasmid DNA sequence of claim 31, further defined as having ATCC Accession Number 74290 and designated Awa LF 24-1.

33. Aspergillus awamori fungal cells comprising the plasmid of claim 31.

63. A mature, native, lactoferrin, an iron binding lobe of a native lactoferrin polypeptide, or an antimicrobial peptide of a native lactoferrin produced and processed when the vector of claim 31 is used to transform an Aspergillus awamori fungal cell, and the transformed Aspergillus awamori fungal cell is grown under conditions suitable for expression of the lactoferrin.

64. An antimicrobial peptide of a native lactoferrin produced when the plasmid DNA sequence of claim 31 is transformed into an Aspergillus awamori fungal cell, and the transformed Aspergillus awamori fungal cell is grown under conditions suitable for expression of the antimicrobial peptide of a native lactoferrin, wherein said antimicrobial peptide comprises an iron-binding domain.

34. A plasmid DNA sequence comprising nucleotide sequence elements operably linked in the following 5'"'"' to 3'"'"' order:

(a) a first DNA sequence as a means for encoding a fungal promoter sequence;

(b) a second DNA sequence as a means for encoding a signal peptide;

(c) a third DNA sequence as a means for encoding an amino terminal portion of a highly expressed endogenous gene the product of which is secreted by Aspergillus cells; and

,

(d) a fourth DNA sequence as a means for encoding a peptide selected from the group consisting of a mature, native, lactoferrin, an iron-binding lobe of a native lactoferrin, and an antimicrobial peptide of a native lactoferrin.

35. The plasmid DNA sequence of claim 34, further comprising a fifth DNA sequence as a means for encoding a peptide linker joining an amino terminal portion of said encoded endogenous Aspergillus polypeptide to the amino terminus of an encoded native lactoferrin polypeptide, iron-binding lobe of a native lactoferrin, or an antimicrobial peptide of a native lactoferrin, the peptide linker comprising a fungal peptidase cleavage site.

36. A process for producing lactoferrin which comprises culturing a transformed Aspergillus fungal cell containing a recombinant plasmid, wherein said plasmid comprises the following components operably linked from 5'"'"' to 3'"'"':

(a) a promoter;

(b) a signal sequence;

(c) a sequence encoding an amino terminal portion of a highly expressed endogenous gene the product of which is secreted by Aspergillus cells; and

,

(d) a nucleotide sequence selected from the group consisting of a nucleotide sequence encoding a mature, native, lactoferrin, a nucleotide sequence encoding an iron-binding lobe of a native lactoferrin and a nucleotide sequence encoding an antimicrobial peptide of a native lactoferrin;

wherein said transformed Aspergillus fungal cells are cultured in a suitable nutrient medium until the mature, native, lactoferrin, the iron-binding lobe of a native lactoferrin, or the antimicrobial peptide of a native lactoferrin, is produced as a fusion product and then processed via an endogenous proteolytic enzyme specific for the linker sequence, wherein the processed mature, native, lactoferrin, the iron-binding lobe of a native lactoferrin, or the antimicrobial peptide of a native lactoferrin is secreted into the nutrient medium and isolated therefrom.

37. The process of claim 36, wherein the plasmid further comprises a sequence encoding a peptide linker joining an amino terminal portion of said encoded endogenous Aspergillus polypeptide to the amino terminus of an encoded native lactoferrin polypeptide, iron-binding lobe of a native lactoferrin, or an antimicrobial peptide of a native lactoferrin, the peptide linker comprising a fungal peptidase cleavage site.

38. The process of claim 37, wherein the peptide linker encoding sequence comprises codons encoding the Kex2 peptidase cleavage site.

39. The process of claim 37, wherein the promoter is selected from genes of the group consisting of an alcohol dehydrogenase gene, an α

-amylase gene, a glucoamylase gene, and a benA gene.

40. The process of claim 39, wherein the promoter is the glucoamylase gene promoter.

41. The process of claim 40, wherein the glucoamylase gene is an A. awamori glucoamylase gene or an A. niger glucoamylase gene.

42. The process of claim 39, wherein said promoter is an α

-amylase gene promoter.

43. The process of claim 42, wherein the α

-amylase gene is an A. oryzae α

-amylase gene.

44. The process of claim 37, wherein the signal peptide-encoding sequence is selected from the genes of the group consisting of a glucoamylase gene and an α

-amylase gene.

45. The process of claim 44, wherein the signal peptide-encoding sequence is selected from an A. awamori glucoamylase gene.

46. The process of claim 44, wherein the signal peptide-encoding sequence is selected from an A. oryzae α

-amylase gene.

47. The process of claim 37, wherein the sequence encoding an amino terminal portion of a highly expressed endogenous gene the product of which is secreted from Aspergillus cells is selected from the group consisting of an α

-amylase gene and a glucoamylase gene.

48. The process of claim 47, wherein the sequence encoding an amino terminal portion of a highly expressed endogenous gene the product of which is secreted from Aspergillus cells is selected from an A. oryzae α

-amylase gene.

49. The process of claim 47, wherein the sequence encoding an amino terminal portion of a highly expressed endogenous gene the product of which is secreted from Aspergillus cells is selected from an A. awamori glucoamylase gene.

50. The process of claim 37, wherein the plasmid further comprises a transcription termination sequence and a selectable marker gene.

51. The process of claim 50, wherein said transcription termination sequence is selected from the group of genes consisting of an α

-amylase gene, a glucoamylase gene, an alcohol dehydrogenase gene, and a benA gene.

52. The process of claim 51, wherein the transcription termination sequence is selected from an A. niger glucoamylase gene.

53. The process of claim 50, wherein the selectable marker gene is selected from the group of genes consisting of a pyr4 gene, a pyrG gene, an amdS gene, an argB gene, a trpC gene, and a phleomycin resistance gene.

54. The process of claim 53, wherein the selectable marker gene is the phleomycin resistance gene.

67. A mature, native, lactoferrin, an iron binding lobe of a native lactoferrin polypeptide, or an antimicrobial peptide of a native lactoferrin produced by the process of claim 36.

68. An antimicrobial peptide of a native lactoferrin produced by the process of claim 36, wherein said antimicrobial peptide comprises an iron-binding domain.

69. A mature, native, lactoferrin, an iron binding lobe of a native lactoferrin polypeptide, or an antimicrobial peptide of a native lactoferrin produced by the process of claim 37.

70. An antimicrobial peptide of a native lactoferrin produced by the process of claim 37, wherein said antimicrobial peptide comprises an iron-binding domain.

71. The mature, native, lactoferrin, the iron binding lobe of a native lactoferrin polypeptide, or the antimicrobial peptide of a native lactoferrin of claim 69, wherein the lactoferrin is selected from the group consisting of human lactoferrin, bovine lactoferrin and porcine lactoferrin.

72. An antimicrobial peptide of a native lactoferrin of claim 69, wherein the lactoferrin is selected from the group consisting of human lactoferrin, bovine lactoferrin and porcine lactoferrin and wherein said antimicrobial peptide comprises an iron-binding domain.

55. A process for producing a mature, native, lactoferrin, an iron-binding lobe of a native lactoferrin, or an antimicrobial peptide of a native lactoferrin which comprises culturing a transformed Aspergillas niger fungal cell containing a recombinant plasmid, wherein said plasmid comprises the following components operably linked from 5'"'"' to 3'"'"':

(a) a promoter from A. niger glucoamylase gene;

(b) a signal peptide-encoding sequence from the A. niger glucoamylase gene;

(c) a sequence encoding an amino terminal of the A. niger glucoamylase gene;

(d) a sequence encoding a peptide linker comprising a Kex2 peptidase cleavage site whereby there is an endogenous proteolytic enzyme specific for said linker sequence;

(e) a nucleotide sequence selected from the group consisting of a nucleotide sequence encoding a mature, native, lactoferrin, a nucleotide sequence encoding an iron-binding lobe of a native lactoferrin and a nucleotide sequence encoding an antimicrobial peptide of a native lactoferrin;

(f) a transcription termination sequence from the A. niger glucoamylase gene; and

(g) a phleomycin resistance selectable marker gene;

wherein said transformed Aspergillus niger fungal cell is cultured in a suitable nutrient medium until the mature, native, lactoferrin, the iron-binding lobe of a native lactoferrin, or the antimicrobial peptide of a native lactoferrin is produced as a fusion product and then processed via an endogenous proteolytic enzyme specific for said linker sequence, wherein the processed mature, native, lactoferrin, the processed iron-binding lobe of a native lactoferrin, or the processed antimicrobial peptide of a native lactoferrin is secreted into the nutrient medium and isolated therefrom.

56. A process for producing lactoferrin which comprises culturing a transformed Aspergillus oryzae fungal cell containing a recombinant plasmid, wherein said plasmid comprises the following components operably linked from 5'"'"' to 3'"'"':

(a) a promoter from A. oryzae α

-amylase gene;

(b) a signal peptide-encoding sequence from the A. oryzae α

-amylase gene;

(c) a sequence encoding an amino terminal portion of the A. oryzae α

-amylase gene;

(d) a sequence encoding a peptide linker comprising a Kex2 peptidase cleavage site whereby there is an endogenous proteolytic enzyme specific for said linker sequence;

(e) a nucleotide sequence selected from the group consisting of a nucleotide sequence encoding a mature, native, lactoferrin, a nucleotide sequence encoding an iron-binding lobe of a native lactoferrin and a nucleotide sequence encoding an antimicrobial peptide of a native lactoferrin;

(f) a transcription termination sequence from the A. niger glucoamylase gene; and

(g) a phleomycin resistance selectable marker gene;

wherein said transformed Aspergillus oryzae fungal cell is cultured in a suitable nutrient medium until the mature, native, lactoferrin, the iron-binding lobe of a native lactoferrin, or the antimicrobial peptide of a native lactoferrin is produced as a fusion product and then processed via an endogenous proteolytic enzyme specific for said linker sequence, wherein the processed mature, native, lactoferrin, the processed iron-binding lobe of a native lactoferrin, or the processed antimicrobial peptide of a native lactoferrin is secreted into the nutrient medium and isolated therefrom.

57. A process for producing lactoferrin which comprises culturing a transformed Aspergillus awamori fungal cell containing a recombinant plasmid, wherein said plasmid comprises the following components operably linked from 5'"'"' to 3'"'"':

(a) a promoter from A. awamori glucoamylase gene;

(b) a signal peptide-encoding sequence from the A. awamori glucoamylase gene;

(c) a sequence encoding an amino terminal portion of the A. awamori glucoamylase gene;

(d) a sequence encoding a peptide linker comprising a Kex2 peptidase cleavage site whereby there is an endogenous proteolytic enzyme specific for said linker sequence;

(e) a nucleotide sequence selected from the group consisting of a nucleotide sequence encoding a mature, native, human lactoferrin, a nucleotide sequence encoding an iron-binding lobe of a native human lactoferrin and a nucleotide sequence encoding an antimicrobial peptide of a native human lactoferrin;

(f) a transcription termination sequence from the A. niger glucoamylase gene; and

(g) a phleomycin resistance selectable marker gene;

wherein said transformed Aspergillus awamori fungal cell is cultured in a suitable nutrient medium until the human lactoferrin, the iron-binding lobe of a native human lactoferrin or the antimicrobial peptide of a native human lactoferrin is produced as a fusion product and then processed via an endogenous proteolytic enzyme specific for said linker sequence, wherein the processed mature, native, human lactoferrin, the processed iron-binding lobe of native human lactoferrin, or the processed antimicrobial peptide of a native human lactoferrin is secreted into the nutrient medium and isolated therefrom.

58. A method of isolating a mature, native, lactoferrin, an iron-binding lobe of a native lactoferrin, or an antimicrobial peptide of a native lactoferrin from fungal nutrient medium comprising culturing a transformed Aspergillus awamori fungal cell containing a recombinant plasmid vector, wherein said plasmid vector comprises a promoter from A. awamori glucoamylase gene, a signal peptide-encoding sequence from the A. awamori glucoamylase gene, a sequence encoding an amino terminal of the A. awamori glucoamylase gene, a sequence encoding a peptide linker comprising a Kex2 peptidase cleavage site whereby there is an endogenous proteolytic enzyme is specific for said linker sequence, a nucleotide sequence selected from the group consisting of a nucleotide sequence encoding a mature, native, lactoferrin, a nucleotide sequence encoding an iron-binding lobe of a native lactoferrin and a nucleotide sequence encoding an antimicrobial peptide of a native lactoferrin, a transcription termination sequence from the A. niger glucoamylase gene, and a phleomycin resistance selectable marker gene and wherein said transformed Aspergillus awamori fungal cells are cultured in a suitable nutrient medium until the mature, native, lactoferrin, the iron-binding lobe of a native lactoferrin, or the antimicrobial peptide of a native lactoferrin is produced as a fusion product and then processed via an endogenous proteolytic enzyme specific for said linker sequence, wherein the processed mature, native, lactoferrin, the processed iron-binding lobe of a native lactoferrin, or the processed antimicrobial peptide of a native lactoferrin is secreted into the nutrient medium and isolated therefrom.

73. A mature, native, lactoferrin, an iron-binding lobe of a native lactoferrin, or an antimicrobial peptide of native lactoferrin produced by a process which comprises culturing a transformed Aspergillas awamori fungal cell containing a recombinant plasmid, wherein said plasmid comprises the following components operably linked from 5'"'"' to 3'"'"':

(a) a promoter from A. awamori glucoamylase gene;

(b) a signal peptide-encoding sequence from the A. awamori glucoamylase gene;

(c) a sequence encoding an amino terminal portion of the A. awamori glucoamylase gene;

(d) a sequence encoding a peptide linker comprising a Kex2 peptidase cleavage site whereby there is an endogenous proteolytic enzyme specific for said linker sequence;

(e) a nucleotide sequence selected from the group consisting of a nucleotide sequence encoding a mature, native, lactoferrin, a nucleotide sequence encoding an iron-binding lobe of a native lactoferrin and a nucleotide sequence encoding an antimicrobial peptide of a native lactoferrin;

(f) a transcription termination sequence from the A. niger glucoamylase gene; and

(g) a phleomycin resistance selectable marker gene;

wherein said transformed Aspergillus awamori fungal cell is cultured in a suitable nutrient medium until the mature, native, lactoferrin, the iron-binding lobe of a native lactoferrin, or the antimicrobial peptide of a native lactoferrin is produced as a fusion product and then processed via an endogenous proteolytic enzyme specific for said linker sequence, wherein the processed mature, native, lactoferrin, the processed iron-binding lobe of a native lactoferrin, or the processed antimicrobial peptide of a native lactoferrin is secreted into the nutrient medium and isolated therefrom.

74. An antimicrobial peptide of a native lactoferrin of claim 73, wherein said antimicrobial peptide comprises an iron-binding domain.