Lysine Decarboxylase Gene Research Articles

Evaluation of Biogenic Amine Degradation Ability of Staphylococcus xylosus JCM 2418 and its Application in Shrimp Paste

ABSTRACT Microbial strains with amine oxidase activity could effectively degrade undesirable biogenic amines in food. Staphylococcus xylosus JCM 2418 was sensitive to common antibiotics, without hemolysis, and had protease activity. A 15% salt concentration was beneficial to the expression of the amine oxidase gene (yobN), restricted the expression of the lysine decarboxylase gene (ldc), and was more effective in degrading biogenic amines. The strain was inoculated in shrimp paste as a co-starter to promote the formation of volatile odor. Additionally, the tyramine, putrescine, cadaverine, and histamine levels were reduced by 42.4, 16.4, 22.2, and 20.8%, respectively.

Screening of strictocidine synthase and lysine decarboxylase gene involved in alkaloid biosynthesis in plants of Catharanthus rosea, Adathoda vasica and Wedelia trilobata

Alkaloids are naturally occurring nitrogenous organic compounds of plant and display vast range of pharmacological properties such as anticancer, antiviral, anti-diabetic, antioxidant and antimicrobial activities. Medicinal plants are the main source of secondary metabolites and the enzymatic pathway involved in its production may be enhanced to increase synthesis of metabolites. The strictocidine synthase (STR) and lysine decarboxylase (LDC) gene are involved in biosynthesis of monoterpenoid indole alkaloid and quinolizidine alkaloid respectively. In the present study, STR and LDC gene were analyzed in Catharanthus roseus, Adathoda vasica and Wedelia trilobata using real time PCR. The PCR results showed S shaped curve with Ct value for amplification of target gene which was found in Catharanthus roseus for STR gene and in Catharanthus roseus and Adathoda vasica for LDC gene. For further confirmation of target, gene samples were separated on agarose gel for size determination and the size of STR gene was found to be 1.1 kb and LDC gene was 1.3 kb respectively. Thus this study should be beneficial for academic as well as industrial point of view from production of alkaloids in plants by enhancing STR and LDC gene synthesis and alkaloids should also be used for isolation and characterization for pharmaceutical applications.

Utilization of a Wheat Sidestream for 5-Aminovalerate Production in Corynebacterium glutamicum.

Production of plastics from petroleum-based raw materials extensively contributes to global pollution and CO2 emissions. Biotechnological production of functionalized monomers can reduce the environmental impact, in particular when using industrial sidestreams as feedstocks. Corynebacterium glutamicum, which is used in the million-ton-scale amino acid production, has been engineered for sustainable production of polyamide monomers. In this study, wheat sidestream concentrate (WSC) from industrial starch production was utilized for production of l-lysine–derived bifunctional monomers using metabolically engineered C. glutamicum strains. Growth of C. glutamicum on WSC was observed and could be improved by hydrolysis of WSC. By heterologous expression of the genes xylA Xc B Cg (xylA from Xanthomonas campestris) and araBAD Ec from E. coli, xylose, and arabinose in WSC hydrolysate (WSCH), in addition to glucose, could be consumed, and production of l-lysine could be increased. WSCH-based production of cadaverine and 5-aminovalerate (5AVA) was enabled. To this end, the lysine decarboxylase gene ldcC Ec from E. coli was expressed alone or for conversion to 5AVA cascaded either with putrescine transaminase and dehydrogenase genes patDA Ec from E. coli or with putrescine oxidase gene puo Rq from Rhodococcus qingshengii and patD Ec . Deletion of the l-glutamate dehydrogenase–encoding gene gdh reduced formation of l-glutamate as a side product for strains with either of the cascades. Since the former cascade (ldcC Ec -patDA Ec ) yields l-glutamate, 5AVA production is coupled to growth by flux enforcement resulting in the highest 5AVA titer obtained with WSCH-based media.

Technological Parameters, Anti-Listeria Activity, Biogenic Amines Formation and Degradation Ability of L. plantarum Strains Isolated from Sheep-Fermented Sausage.

The aim of this work was to identify and characterize, from a technological and safety point of view, the lactic acid bacteria (LAB) isolated from traditional sheep-fermented sausage. First, LABs were identified then were screened for some technological parameters such as acidifying and growth ability, proteolytic and lipolytic activity and for antimicrobial activity. Finally, biogenic amine production and degradation abilities were also evaluated. This research reveals the predominance of Lactiplantibacillus (L.) plantarum on LAB community. Almost all L. plantarum strains were active against Listeria monocytogenes strains (inhibition zone diameters > 1 cm). None of the tested strains were positive in histidine (hdcA), lysine (ldc) and tyrosine (tyrdc) decarboxylase genes and only one (L. plantarum PT9-2) was positive to the agmatine deiminase (agdi) gene. Furthermore, given the positive results of the sufl (multi-copper oxidase) gene detection, all strains showed a potential degradation ability of biogenic amines.

Identification of biogenic amine-producing microbes during fermentation of ganjang, a Korean traditional soy sauce, through metagenomic and metatranscriptomic analyses

Microbes responsible for producing biogenic amines (BAs) during fermentation of ganjang, a Korean traditional soy sauce, were investigated through metagenomic and metatranscriptomic analyses. BA analysis revealed that cadaverine, putrescine, tyramine, and histamine were generated during ganjang fermentation and BA-producing decarboxylase sequences were searched from metagenomic contigs through BlastP and sequence similarity network analyses. A total of 16 putative BA-producing decarboxylase sequences, including five ornithine decarboxylases (ODC), one lysine decarboxylase (LDC), one histidine decarboxylase (HDC), and nine tyrosine decarboxylases (TDC) were identified and phylogenetically classified. BA-producing gene and expression analysis suggested that cadaverine and histamine might only be produced by the LDC gene of Staphylococcus showing relatively high expression levels and the HDC gene of Tetragenococcus showing very low expression levels, respectively, during the middle fermentation periods. Additionally, putrescine and tyramine might be produced by the ODC and TDC genes, respectively, by various microbes during the entire fermentation period. The analyses also suggested that the ODC genes of Bacillus and Halomonas, expressed at a low level, might be responsible for producing putrescine during early fermentation, while after 60 days the ODC gene of Lactobacillus, expressed at a comparatively high level, might be dominantly responsible for producing putrescine. Additionally, the TDC genes of Bacillus, Enterococcus, and Virgibacillus might be responsible for producing tyramine at 20 and 40 days of fermentation, while after 60 days the TDC gene of Tetragenococcus, which was highly expressed at this time point, along with Virgibacillus and Enterococcus, might be majorly responsible for producing tyramine.

The chromosome-scale reference genome of black pepper provides insight into piperine biosynthesis

Black pepper (Piper nigrum), dubbed the ‘King of Spices’ and ‘Black Gold’, is one of the most widely used spices. Here, we present its reference genome assembly by integrating PacBio, 10x Chromium, BioNano DLS optical mapping, and Hi-C mapping technologies. The 761.2 Mb sequences (45 scaffolds with an N50 of 29.8 Mb) are assembled into 26 pseudochromosomes. A phylogenomic analysis of representative plant genomes places magnoliids as sister to the monocots-eudicots clade and indicates that black pepper has diverged from the shared Laurales-Magnoliales lineage approximately 180 million years ago. Comparative genomic analyses reveal specific gene expansions in the glycosyltransferase, cytochrome P450, shikimate hydroxycinnamoyl transferase, lysine decarboxylase, and acyltransferase gene families. Comparative transcriptomic analyses disclose berry-specific upregulated expression in representative genes in each of these gene families. These data provide an evolutionary perspective and shed light on the metabolic processes relevant to the molecular basis of species-specific piperine biosynthesis.

Modular metabolic engineering of lysine supply for enhanced production of bacitracin in Bacillus licheniformis.

Bacitracin is a kind of macrocyclic dodecapeptide that produced by Bacillus, precursor supply served as a critical role in bacitracin production, here, the aim of this study wants to improve bacitracin production by enhancing Lysine (Lys) supply via metabolic engineering of B. licheniformis DW2, an industrial strain for bacitracin production. Firstly, exogenous addition of Lys was proven to be favorable for bacitracin production, and the strain LYS2 was attained through strengthening Lys synthetic pathways via overexpressing diaminopimelate decarboxylase LysA from B. licheniformis and diaminopimelate dehydrogenase DdH from Corynebacterium glutamicum, and the bacitracin produced by LYS2 was increased to 838.53 U/mL by 10.85%, compared with that of DW2 (756.45 U/mL). Secondly, oxaloacetate, the precursor of Lys, was accumulated by overexpressing pyruvate carboxylase PycA in LYS2, and 17.06% increase of bacitracin yield was attained in LYS3 (885.53 U/mL), compared with DW2. Thirdly, lysine decarboxylase gene yaaO was deleted to weaken Lys degradation, and the attained strain LYS4 showed further increased bacitracin production from 885.53 to 923.43 U/mL. Lastly, the transporter LysE was confirmed to act as a Lys exporter; LysP and YvsH were identified as the Lys importers in B. licheniformis DW2, and bacitracin yield was increased to 975.43 U/mL by 28.95% in final strain LYS5 via engineering the Lys transporters. Taken together, this study implied that metabolic engineering of Lys supply modules is an efficient strategy for enhancement production of bacitracin, and provided a promising strain of B. licheniformis for industrial production of bacitracin.

Metabolic diversification of nitrogen-containing metabolites by the expression of a heterologous lysine decarboxylase gene in Arabidopsis.

SummaryLysine decarboxylase converts l‐lysine to cadaverine as a branching point for the biosynthesis of plant Lys‐derived alkaloids. Although cadaverine contributes towards the biosynthesis of Lys‐derived alkaloids, its catabolism, including metabolic intermediates and the enzymes involved, is not known. Here, we generated transgenic Arabidopsis lines by expressing an exogenous lysine/ornithine decarboxylase gene from Lupinus angustifolius (La‐L/ODC) and identified cadaverine‐derived metabolites as the products of the emerged biosynthetic pathway. Through untargeted metabolic profiling, we observed the upregulation of polyamine metabolism, phenylpropanoid biosynthesis and the biosynthesis of several Lys‐derived alkaloids in the transgenic lines. Moreover, we found several cadaverine‐derived metabolites specifically detected in the transgenic lines compared with the non‐transformed control. Among these, three specific metabolites were identified and confirmed as 5‐aminopentanal, 5‐aminopentanoate and δ‐valerolactam. Cadaverine catabolism in a representative transgenic line (DC29) was traced by feeding stable isotope‐labeled [α‐15N]‐ or [ε‐15N]‐l‐lysine. Our results show similar 15N incorporation ratios from both isotopomers for the specific metabolite features identified, indicating that these metabolites were synthesized via the symmetric structure of cadaverine. We propose biosynthetic pathways for the metabolites on the basis of metabolite chemistry and enzymes known or identified through catalyzing specific biochemical reactions in this study. Our study shows that this pool of enzymes with promiscuous activities is the driving force for metabolite diversification in plants. Thus, this study not only provides valuable information for understanding the catabolic mechanism of cadaverine but also demonstrates that cadaverine accumulation is one of the factors to expand plant chemodiversity, which may lead to the emergence of Lys‐derived alkaloid biosynthesis.

Genomic Characterization Provides New Insights Into the Biosynthesis of the Secondary Metabolite Huperzine a in the Endophyte Colletotrichum gloeosporioides Cg01.

A reliable source of Huperzine A (HupA) meets an urgent need due to its wide use in Alzheimer's disease treatment. In this study, we sequenced and characterized the whole genomes of two HupA-producing endophytes, Penicillium polonicum hy4 and Colletotrichum gloeosporioides Cg01, to clarify the mechanism of HupA biosynthesis. The whole genomes of hy4 and Cg01 were 33.92 and 55.77 Mb, respectively. We compared the differentially expressed genes (DEGs) between the induced group (with added extracts of Huperzia serrata) and a control group. We focused on DEGs with similar expression patterns in hy4 and Cg01. The DEGs identified in GO (Gene ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways were primarily located in carbon and nitrogen metabolism and nucleolus, ribosome, and rRNA processing. Furthermore, we analyzed the gene expression for HupA biosynthesis genes proposed in plants, which include lysine decarboxylase (LDC), copper amine oxidase (CAO), polyketides synthases (PKS), etc. Two LDCs, one CAO, and three PKSs in Cg01 were selected as prime candidates for further validation. We found that single candidate biosynthesis-gene knock-out did not influence the HupA production, while both LDC gene knock-out led to increased HupA production. These results reveal that HupA biosynthesis in endophytes might differ from that proposed in plants, and imply that the HupA-biosynthesis genes in endophytic fungi might co-evolve with the plant machinery rather than being acquired through horizontal gene transfer (HGT). Moreover, we analyzed the function of the differentially expressed epigenetic modification genes. HupA production of the histone acetyltransferase (HAT) deletion mutant ΔCgSAS-2 was not changed, while that of the histone methyltransferase (HMT) and histone deacetylase (HDAC) deletion mutants ΔCgClr4, ΔCgClr3, and ΔCgSir2-6 was reduced. Recovery of HupA-biosynthetic ability can be achieved by retro-complementation, demonstrating that HMT and HDACs associated with histone modification are involved in the regulation of HupA biosynthesis in endophytic fungi. This is the first report on epigenetic modification in high value secondary metabolite- producing endophytes. These findings shed new light on HupA biosynthesis and regulation in HupA-producing endophytes and are crucial for industrial production of HupA from fungi.

Transcriptome analysis and identification of key genes involved in 1-deoxynojirimycin biosynthesis of mulberry (Morus alba L.).

Mulberry (Morus alba L.) represents one of the most commonly utilized plants in traditional medicine and as a nutritional plant used worldwide. The polyhydroxylated alkaloid 1-deoxynojirimycin (DNJ) is the major bioactive compounds of mulberry in treating diabetes. However, the DNJ content in mulberry is very low. Therefore, identification of key genes involved in DNJ alkaloid biosynthesis will provide a basis for the further analysis of its biosynthetic pathway and ultimately for the realization of synthetic biological production. Here, two cDNA libraries of mulberry leaf samples with different DNJ contents were constructed. Approximately 16 Gb raw RNA-Seq data was generated and de novo assembled into 112,481 transcripts, with an average length of 766 bp and an N50 value of 1,392. Subsequently, all unigenes were annotated based on nine public databases; 11,318 transcripts were found to be significantly differentially regulated. A total of 38 unique candidate genes were identified as being involved in DNJ alkaloid biosynthesis in mulberry, and nine unique genes had significantly different expression. Three key transcripts of DNJ biosynthesis were identified and further characterized using RT-PCR; they were assigned to lysine decarboxylase and primary-amine oxidase genes. Five CYP450 transcripts and two methyltransferase transcripts were significantly associated with DNJ content. Overall, the biosynthetic pathway of DNJ alkaloid was preliminarily speculated.

Cloning, expression, and functional analysis of lysine decarboxylase in mulberry (Morus alba L.)

1-Deoxynojirimycin (DNJ) is the main bioactive compound of Morus alba L.. DNJ has pharmacological effects, including blood sugar level regulation and antiviral activity. In this study, the mulberry lysine decarboxylase gene (MaLDC), which is involved in the biosynthesis of DNJ alkaloids, was cloned, expressed, and functionally verified. MaLDC was induced and expressed in Escherichia coli BL21 (DE3). The recombinant soluble MaLDC protein had a relative molecular mass of 24.0 kDa. The protein was purified by Ni-NTA separation. The results showed that MaLDC protein could catalyze lysine decarboxylation to produce cadaverine. The Km and Vmax values were 19.2 μM and 3.31 μM/min, respectively. Quantitative real-time reverse transcription polymerase chain reaction revealed that MaLDC expression was positively correlated with DNJ content (P < 0.001), indicating that the MaLDC could encode a functional protein involved in the biosynthesis of DNJ alkaloid in mulberry. Our results provided a foundation for further studies of the enzymatic properties of LDC and established a basis for the analysis of key enzymes involved in the biosynthetic pathway of mulberry DNJ alkaloid.

Expression and functional analysis of the lysine decarboxylase and copper amine oxidase genes from the endophytic fungus Colletotrichum gloeosporioides ES026

Huperzine A (HupA) isolated from Huperzia serrata is an important compound used to treat Alzheimer’s disease (AD). Recently, HupA was reported in various endophytic fungi, with Colletotrichum gloeosporioides ES026 previously isolated from H. serrata shown to produce HupA. In this study, we performed next-generation sequencing and de novo RNA sequencing of C. gloeosporioides ES026 to elucidate the molecular functions, biological processes, and biochemical pathways of these unique sequences. Gene ontology and Kyoto Encyclopedia of Genes and Genomes assignments allowed annotation of lysine decarboxylase (LDC) and copper amine oxidase (CAO) for their conversion of L-lysine to 5-aminopentanal during HupA biosynthesis. Additionally, we constructed a stable, high-yielding HupA-expression system resulting from the overexpression of CgLDC and CgCAO from the HupA-producing endophytic fungus C. gloeosporioides ES026 in Escherichia coli. Quantitative reverse transcription polymerase chain reaction analysis confirmed CgLDC and CgCAO expression, and quantitative determination of HupA levels was assessed by liquid chromatography high-resolution mass spectrometry, which revealed that elevated expression of CgLDC and CgCAO produced higher yields of HupA than those derived from C. gloeosporioides ES026. These results revealed CgLDC and CgCAO involvement in HupA biosynthesis and their key role in regulating HupA content in C. gloeosporioides ES026.

Genome-Based Genetic Tool Development for Bacillus methanolicus: Theta- and Rolling Circle-Replicating Plasmids for Inducible Gene Expression and Application to Methanol-Based Cadaverine Production

Bacillus methanolicus is a thermophilic methylotroph able to overproduce amino acids from methanol, a substrate not used for human or animal nutrition. Based on our previous RNA-seq analysis a mannitol inducible promoter and a putative mannitol activator gene mtlR were identified. The mannitol inducible promoter was applied for controlled gene expression using fluorescent reporter proteins and a flow cytometry analysis, and improved by changing the -35 promoter region and by co-expression of the mtlR regulator gene. For independent complementary gene expression control, the heterologous xylose-inducible system from B. megaterium was employed and a two-plasmid gene expression system was developed. Four different replicons for expression vectors were compared with respect to their copy number and stability. As an application example, methanol-based production of cadaverine was shown to be improved from 6.5 to 10.2 g/L when a heterologous lysine decarboxylase gene cadA was expressed from a theta-replicating rather than a rolling-circle replicating vector. The current work on inducible promoter systems and compatible theta- or rolling circle-replicating vectors is an important extension of the poorly developed B. methanolicus genetic toolbox, valuable for genetic engineering and further exploration of this bacterium.

Improved screening procedure for biogenic amine production by lactic acid bacteria and Enterobacteria

Shiling L., Caihong J., Xinglian X., Chengjian X., Kaixiong L., Ruihua S. (2015): Improved screening procedure for biogenic amine production by lactic acid bacteria and Enterobacteria. Czech J. Food Sci., 33: 19–26. An improved screening procedure was developed for the detection of amino acid decarboxylase-positive microorganisms (especially lactic acid bacteria and Enterobacteria). Monolayer culture and double layer colour development methods for the detection of amino acid decarboxylase-positive lactic acid bacteria and Enterobacteria were established. Bio genic amine-positive bacteria strain was isolated directly from the samples. The applicability and detection level of the designed medium were quantitatively evaluated by the confirmation of the amine-forming capacity using an HPLC procedure, while tyrosine decarboxylase and lysine decarboxylase genes were detected by PCR with specific primers. The screening method showed a good correlation with the chemical analysis and molecular detection. Enterobacter

Cadaverine production by heterologous expression of Klebsiella oxytoca lysine decarboxylase

Cadaverine, as a biogenic amine, is an important platform chemical for the production of industrial polymers, such as polyamides, polyurethanes, and nylon. Previous efforts focused on the bio-based production of cadaverine using two lysine decarboxylases of Escherichia coli CadA and LdcC. In this study, we report the biotransformation of cadaverine using a lysine decarboxylase from Klebsiella oxytoca. Codon optimization of the gene encoding this enzyme was carried on for the heterologous expression in E. coli, which led to a system that converted more than 24% lysine-HCl to cadaverine compared to the same system expressing CadA. The system was further optimized by using three different inducible promoters to control the expression of lysine decarboxylase gene of K. oxytoca in E. coli. The final optimized system converted lysine-HCl to cadaverine at a conversion rate of 0.133%/min/g. When the optimized system described above is coupled to an industrial process, the combined process has the potential to produce cadaverine with high conversion efficiency (46%) from sugar.

Transcriptional analysis of different stress response genes in Escherichia coli strains subjected to sodium chloride and lactic acid stress.

Survival of Escherichia coli in food depends on its ability to adapt against encountered stress typically involving induction of stress response genes. In this study, the transcriptional induction of selected acid (cadA, speF) and salt (kdpA, proP, proW, otsA, betA) stress response genes was investigated among five E. coli strains, including three Shiga toxin-producing strains, exposed to sodium chloride or lactic acid stress. Transcriptional induction upon lactic acid stress exposure was similar in all but one E. coli strain, which lacked the lysine decarboxylase gene cadA. In response to sodium chloride stress exposure, proW and otsA were similarly induced, while significant differences were observed between the E. coli strains in induction of kdpA, proP and betA. The kdpA and betA genes were significantly induced in four and three strains, respectively, whereas one strain did not induce these genes. The proP gene was only induced in two E. coli strains. Interestingly, transcriptional induction differences in response to sodium chloride stress exposure were associated with survival phenotypes observed for the E. coli strains in cheese as the E. coli strain lacking significant induction in three salt stress response genes investigated also survived poorly compared to the other E. coli strains in cheese.

Revisiting anabasine biosynthesis in tobacco hairy roots expressing plant lysine decarboxylase gene by using &lt;sup&gt;15&lt;/sup&gt;N-labeled lysine

Revisiting anabasine biosynthesis in tobacco hairy roots expressing plant lysine decarboxylase gene by using &lt;sup&gt;15&lt;/sup&gt;N-labeled lysine

A Pathoadaptive Deletion in an Enteroaggregative Escherichia coli Outbreak Strain Enhances Virulence in a Caenorhabditis elegans Model

Enteroaggregative Escherichia coli (EAEC) strains are important diarrheal pathogens. EAEC strains are defined by their characteristic stacked-brick pattern of adherence to epithelial cells but show heterogeneous virulence and have different combinations of adhesin and toxin genes. Pathoadaptive deletions in the lysine decarboxylase (cad) genes have been noted among hypervirulent E. coli subtypes of Shigella and enterohemorrhagic E. coli. To test the hypothesis that cad deletions might account for heterogeneity in EAEC virulence, we developed a Caenorhabditis elegans pathogenesis model. Well-characterized EAEC strains were shown to colonize and kill C. elegans, and differences in virulence could be measured quantitatively. Of 49 EAEC strains screened for lysine decarboxylase activity, 3 tested negative. Most notable is isolate 101-1, which was recovered in Japan, from the largest documented EAEC outbreak. EAEC strain 101-1 was unable to decarboxylate lysine in vitro due to deletions in cadA and cadC, which, respectively, encode lysine decarboxylase and a transcriptional activator of the cadAB genes. Strain 101-1 was significantly more lethal to C. elegans than control strain OP50. Lethality was attenuated when the lysine decarboxylase defect was complemented from a multicopy plasmid and in single copy. In addition, restoring lysine decarboxylase function produced derivatives of 101-1 deficient in aggregative adherence to cultured human epithelial cells. Lysine decarboxylase inactivation is pathoadapative in an important EAEC outbreak strain, and deletion of cad genes could produce hypervirulent EAEC lineages in the future. These results suggest that loss, as well as gain, of genetic material can account for heterogeneous virulence among EAEC strains.

Lysine decarboxylase of Vibrio parahaemolyticus: kinetics of transcription and role in acid resistance

The aim of this study was to investigate the detailed mechanisms of acid resistance in Vibrio parahaemolyticus. All 11 strains of V. parahaemolyticus survived lethal acidic conditions following acid adaptation, and accumulation of cadaverine was detected. The addition of lysine improved survival, suggesting that lysine decarboxylase plays a role in the adaptive acid tolerance response. Two open reading frames (ORF) in V. parahaemolyticus, which are separated by a noncoding region, were found to be highly homologous to bacterial lysine decarboxylase (cadA) and lysine/cadaverine antiporter (cadB) genes. Transcriptional analyses of this operon revealed acid induction and enhanced induction by external lysine. The relative expression ratio of each transcript was found to follow the trend of cadA mRNA > cadB mRNA > cadBA bi-cistronic mRNA. A mutated strain, with a disrupted cadA gene, showed attenuated acid survival. We identified the lysine decarboxylase gene operon of V. parahaemolyticus. Expression of this operon was induced under acidic conditions. The cadA-mutated strain constructed in this study showed weaker tolerance to acidic conditions than the wild-type strain. Vibrio parahaemolyticus utilizes the lysine decarboxylation pathway for survival in acidic conditions.

CHILLING TOLERANCE OF CUCUMBER DURING GERMINATION IS RELATED TO EXPRESSION OF LYSINE DECARBOXYLASE GENE

Using cDNA-AFLP technique, a specific fragment was isolated from cucumber cultivar Changchun mici possessing chilling tolerance induced at low temperature (15℃). This fragment, named cctr 132, could not be induced in the chilling sensitive cucumber cultivar Beijing jietou. After recovering the fragment, sequencing and translating, the results of blastx and blastp in GenBank of NCBI indicated that CCTR132 had 88.37% identities and 100% positives with Oryza sativa putative lysine decarboxylase-like protein respectively, and PGGXGTXXE, the putative conserved domain of lysine decarboxylase family, was detected from CCTR132, suggesting the cucumber chilling tolerance during germination is related to the expression of the lysine decarboxylase gene.