title: Improvement of multiple-stress tolerance and lactic acid production in Lactococcus lactis NZ9000 under conditions of thermal stress by heterologous expression of Escherichia coli DnaK.
abstract: The effects of nisin-induced dnaK expression in Lactococcus lactis were examined, and this expression was shown to improve stress tolerance and lactic acid fermentation efficiency. Using a nisin-inducible expression system, DnaK proteins from L. lactis (DnaK(Lla)) and Escherichia coli (DnaK(Eco)) were produced in L. lactis NZ9000. In comparison to a strain harboring the empty vector pNZ8048 (designated NZ-Vector) and one expressing dnaK(Lla) (designated NZ-LDnaK), the dnaK(Eco)-expressing strain, named NZ-EDnaK, exhibited more tolerance to heat stress at 40 degrees C in GM17 liquid medium. The cell viability of NZ-Vector was reduced 4.6-fold after 6 h of heat treatment. However, NZ-EDnaK showed 13.5-fold increased viability under these conditions, with a very low concentration of DnaK(Eco) production. Although the heterologous expression of dnaK(Eco) did not effect DnaK(Lla) production, heat treatment increased the DnaK(Lla) level 3.5- and 3.6-fold in NZ-Vector and NZ-EDnaK, respectively. Moreover, NZ-EDnaK showed tolerance to multiple stresses, including 3% NaCl, 5% ethanol, and 0.5% lactic acid (pH 5.47). In CMG medium, the lactate yield and the maximum lactate productivity of NZ-EDnaK were higher than the corresponding values for NZ-Vector at 30 degrees C. Interestingly, at 40 degrees C, these values of NZ-EDnaK were not significantly different from the corresponding values for the control strain at 30 degrees C. Lactate dehydrogenase (LDH) activity was also found to be stable at 40 degrees C in the presence of DnaK(Eco). These findings suggest that the heterologous expression of dnaK(Eco) enhances the quality control of proteins and enzymes, resulting in improved growth and lactic acid fermentation at high temperature.
authors.affiliation: Laboratory of Microbial Technology, Division of Microbial Science and Technology, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
authors.lastname: Abdullah-Al-Mahin
authors.forename: Shinya
authors.initials: S
authors.lastname: Sugimoto
authors.forename: Chihana
authors.initials: C
authors.lastname: Higashi
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Matsumoto
authors.forename: Kenji
authors.initials: K
authors.lastname: Sonomoto
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001709:Biotechnology; D003470:Culture Media; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005285:Fermentation; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D018869:Heat-Shock Response / Q000502:physiology*; D006358:Hot Temperature; D019344:Lactic Acid / Q000378:metabolism*; D013294:Lactococcus lactis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology*; D009561:Nisin / Q000494:pharmacology; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D011994:Recombinant Proteins; D009561:Nisin; D019344:Lactic Acid; C063842:dnaK protein, E coli
references.citation: Appl Environ Microbiol. 2004 Oct;70(10):5929-36
references.pmid: 15466535
references.citation: Appl Microbiol Biotechnol. 2007 Dec;77(4):909-15
references.pmid: 17960374
references.citation: Appl Environ Microbiol. 2003 Feb;69(2):917-25
references.pmid: 12571012
references.citation: Mol Microbiol. 1999 Sep;33(6):1152-61
references.pmid: 10510230
references.citation: J Mol Biol. 1965 Mar;11:476-90
references.pmid: 14267270
references.citation: J Bacteriol. 1977 Jul;131(1):82-91
references.pmid: 17595
references.citation: Appl Environ Microbiol. 2003 Aug;69(8):4951-65
references.pmid: 12902291
references.citation: Biopolymers. 2000;55(1):62-73
references.pmid: 10931442
references.citation: J Appl Microbiol. 2002;93(6):1003-11
references.pmid: 12452956
references.citation: J Dairy Sci. 2000 Apr;83(4):894-907
references.pmid: 10791807
references.citation: Mol Microbiol. 1993 Aug;9(4):671-80
references.pmid: 7901731
references.citation: Biosci Biotechnol Biochem. 2008 Mar;72(3):811-22
references.pmid: 18323638
references.citation: Curr Opin Biotechnol. 1995 Oct;6(5):494-500
references.pmid: 7579660
references.citation: J Bacteriol. 1998 Aug;180(15):3873-81
references.pmid: 9683484
references.citation: Annu Rev Microbiol. 1998;52:41-79
references.pmid: 9891793
references.citation: Annu Rev Biochem. 1986;55:1151-91
references.pmid: 2427013
references.citation: Appl Environ Microbiol. 2003 Apr;69(4):2044-51
references.pmid: 12676681
references.citation: J Biosci Bioeng. 2008 Oct;106(4):324-36
references.pmid: 19000607
references.citation: J Bacteriol. 1989 May;171(5):2337-46
references.pmid: 2651398
references.citation: Acta Biochim Pol. 2007;54(3):509-22
references.pmid: 17882322
references.citation: Curr Microbiol. 2001 Nov;43(5):346-50
references.pmid: 11688799
references.citation: Curr Opin Microbiol. 1999 Apr;2(2):148-52
references.pmid: 10322169
references.citation: Appl Environ Microbiol. 1997 May;63(5):1826-37
references.pmid: 9143115
references.citation: Nature. 1991 Mar 14;350(6314):165-7
references.pmid: 2005967
references.citation: J Bacteriol. 1991 Jul;173(14):4404-10
references.pmid: 2066337
references.citation: Annu Rev Genet. 1984;18:295-329
references.pmid: 6442118
references.citation: Mol Microbiol. 1995 Feb;15(3):421-9
references.pmid: 7540247
references.citation: Appl Environ Microbiol. 1997 May;63(5):1953-8
references.pmid: 9143127
references.citation: J Bacteriol. 1997 Feb;179(4):1153-64
references.pmid: 9023197
references.citation: Appl Environ Microbiol. 1989 Dec;55(12):3119-23
references.pmid: 16348073
references.citation: Appl Environ Microbiol. 1996 Oct;62(10):3662-7
references.pmid: 8837421
references.citation: FEMS Microbiol Lett. 2007 Aug;273(1):12-21
references.pmid: 17559397
references.citation: J Bacteriol. 1987 Jan;169(1):283-90
references.pmid: 3025174
references.citation: Trends Biochem Sci. 1991 Apr;16(4):135-40
references.pmid: 1877088
references.citation: Appl Environ Microbiol. 1994 Nov;60(11):4174-7
references.pmid: 16349445
references.citation: Appl Environ Microbiol. 1991 May;57(5):1408-12
references.pmid: 16348482
references.citation: J Biol Chem. 1989 Dec 15;264(35):21122-30
references.pmid: 2531744
references.citation: Int J Food Microbiol. 2000 Apr 10;55(1-3):83-6
references.pmid: 10791722
references.citation: Protein Eng. 2002 Jan;15(1):35-41
references.pmid: 11842236
references.citation: Cell. 1990 Sep 7;62(5):939-44
references.pmid: 2203539
references.citation: Trends Biotechnol. 2004 Jul;22(7):346-53
references.pmid: 15245907
references.citation: Can J Microbiol. 2004 Oct;50(10):845-51
references.pmid: 15644899
references.citation: Appl Environ Microbiol. 1999 Jul;65(7):3033-41
references.pmid: 10388700
references.citation: EMBO J. 1990 Dec;9(12):4027-36
references.pmid: 2249663
references.citation: J Bacteriol. 1992 Nov;174(22):7436-44
references.pmid: 1429465
references.citation: Microbiology (Reading). 1996 Jul;142 ( Pt 7):1685-91
references.pmid: 8757733
references.citation: Proc Natl Acad Sci U S A. 1991 Apr 1;88(7):2874-8
references.pmid: 1826368
references.citation: Microbiology (Reading). 1997 Mar;143(Pt 3):999-1017
references.pmid: 9296790
references.citation: J Biosci Bioeng. 2003;96(2):129-33
references.pmid: 16233497
references.citation: J Biol Chem. 2001 Jan 19;276(3):1814-21
references.pmid: 11042186