Thermostability and regulation of Clostridium thermocellum L-lactate dehydrogenase expressed in Escherichia coli

Assa, P
Ozkan, M
Özcengiz, Gülay
In this study, L-lactate dehydrogenase (L-LDH) of Clostridium thermocellum previously cloned aid expressed in Escherichia coli FMJ39 was partially purified and characterised. Optimum temperature and pH of the enzyme were found as 50 degrees C and 7.5, respectively. Different concentrations of Mn2+ did not affect the enzyme activity. Addition of 20-30 mM Mg2+, or the other hand, increased the LDH activity by about 10%. Relatively high concentrations of NaCl (2 M), fructose-1,6-diphosphate (FDP, 5 mM), ATP (10 mM) and NAD (40 mM) decreased LDH activity by 36, 25, 40 and 100%, respectively. Oxamate and oxalate inhibited LDH activity by 41 and 28%, respectively, when each was added at a concentration of 0.5 mM. When compared to its non-thermotolerant counterparts, the enzyme was found to be very stable when incubated at room temperature, 4 degrees C and even at 50 degrees C.


Cloning, sequencing and expression of L-lactate dehydrogenase gene from clostridium thermocellum and isolation, characterization and transformation of various cellulolytic, thermophilic, ethanol-producing bacteria
Özkan, Melek; Özcengiz, Gülay; Ögel, Zümrüt B.; Department of Biotechnology (2002)
In this study, the structural gene for L-lactate dehydrogenase (LDH; EC. 1.1. 1.27) was cloned and characterized for the first time from Clostridium thermocellum 27405 in Escherichia coli. A 357 bp PCR product of predicted size was obtained with degenerate primers designed for conserved regions of Idh genes of different organisms. This amplicon was used as a probe to screen a Lambda Zap II phage library of C. thermocellum genomic DNA. One positive clone contained an insert of 2.5 kb which included an open r...
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In this study 24 thermoacidophilic archeal and bacterial strains isolated from hot-springs and hot-soils were screened for their ability to produce intracellular alkaline proteases. The protease activities of the strains, based on azocasein hydrolysis, showed a variation from 0.6 to 5.1 U. The cell extracts of three most potent producers were further examined and it was found that their proteases exhibited maximum activity at 60-70 degreesC and showed a pH Optimum over a range of pH 7.0-8.5. Gelatin zymogra...
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Günalp, Sinem; Gürsel, Mayda; Department of Biology (2015)
Immunological mechanisms making contribution to discriminating signals obtained from commensal versus pathogenic bacteria is an active area of research and recent evidence proposes that commensals and pathogens might express discrete variants of pathogen associated molecular patterns (PAMP). We hypothesized that as a major member of PAMP, bacterial DNA (bacDNA) originating from commensals versus pathogens might possess distinct immunostimulatory activities, enabling their dis- crimination by the immune syst...
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Citation Formats
P. Assa, M. Ozkan, and G. Özcengiz, “Thermostability and regulation of Clostridium thermocellum L-lactate dehydrogenase expressed in Escherichia coli,” ANNALS OF MICROBIOLOGY, pp. 193–197, 2005, Accessed: 00, 2020. [Online]. Available: