Accumulation Of Cadaverine Research Articles

Effects of Lactic Acid Bacteria on Reducing the Formation of Biogenic Amines and Improving the Formation of Antioxidant Compounds in Traditional African Sourdough Flatbread Fermentation.

This study investigated the safety and functionality of traditional African sourdough flatbread (kisra), based on the content of biogenic amines (BAs) and antioxidant compounds and their improvement using lactic acid bacteria (LAB) species. The primary BAs detected in naturally fermented kisra were tyramine, histamine, putrescine, and cadaverine, with putrescine being the most abundant after baking. In vitro BA production of microorganisms isolated from kisra sourdough revealed that the Enterococcus genus contributed to tyramine accumulation, whereas presumptive yeasts may contribute to putrescine and cadaverine accumulation. The use of LAB species, including Lactiplantibacillus plantarum, Limosilactobacillus fermentum, Levilactobacillus brevis, and Weissella cibaria, significantly reduced putrescine content to less than about 23% of that of naturally fermented kisra, and eliminated tyramine, histamine, and cadaverine formation. Meanwhile, DPPH scavenging activity, total polyphenolic content, and tannin content in naturally fermented kisra were 85.16%, 1386.50 µg/g, and 33.16 µg/g, respectively. The use of LAB species did not affect the DPPH scavenging activity or tannin content but significantly increased the total phenolic content by up to 20% compared to naturally fermented kisra. Therefore, fermentation with LAB starter cultures might be a promising approach to improve the safety related to BAs as well as the functionality of kisra bread.

A novel co-production of cadaverine and succinic acid based on a thermal switch system in recombinant Escherichia coli

BackgroundPolyamide (nylon) is an important material, which has aroused plenty of attention from all aspects. PA 5.4 is one kind of nylon with excellent property, which consists of cadaverine and succinic acid. Due to the environmental pollution, bio-production of cadaverine and succinic acid has been more attractive due to the less pollution and environmental friendliness. Microbes, like Escherichia coli, has been employed as cell factory to produce cadaverine and succinic acid. However, the accumulation of cadaverine will cause severe damage on cells resulting in inhibition on cell growth and cadaverine production. Herein, a novel two stage co-production of succinic acid and cadaverine was designed based on an efficient thermos-regulated switch to avoid the inhibitory brought by cadaverine.ResultsThe fermentation process was divided into two phase, one for cell growth and lysine production and the other for cadaverine and succinic acid synthesis. The genes of ldhA and ackA were deleted to construct succinic acid pathway in cadaverine producer strain. Then, a thermal switch system based on pR/pL promoter and CI857 was established and optimized. The fermentation conditions were investigated that the optimal temperature for the first stage was determined as 33 ℃ and the optimal temperature for the second stage was 39 ℃. Additionally, the time to shifting temperature was identified as the fermentation anaphase. For further enhance cadaverine and succinic acid production, a scale-up fermentation in 5 L bioreactor was operated. As a result, the titer, yield and productivity of cadaverine was 55.58 g/L, 0.38 g/g glucose and 1.74 g/(L·h), respectively. 28.39 g/L of succinic acid was also obtained with yield of 0.19 g/g glucose.ConclusionThe succinic acid metabolic pathway was constructed into cadaverine producer strain to realize the co-production of succinic acid and cadaverine. This study provided a novel craft for industrial co-production of cadaverine and succinic acid.

Enhancing pH stability of lysine decarboxylase via rational engineering and its application in cadaverine industrial production

Cadaverine, an important C5 platform compound, is the raw material of polyamides. Under a carbon neutral context, cadaverine bio-production using lysine decarboxylase as a catalyst from the sustainable resource L-lysine is more attractive than chemical synthesis from fossil resources because it is environmentally-friendly and highly efficient. However, the alkaline conditions caused by accumulation of cadaverine decreases lysine decarboxylase activity, which limits its industrial applications. Herein, we aimed to improve cadaverine enzymatic production via enhancing stability of lysine decarboxylase from Escherichia coli (EcCadA) under alkaline pH by rational engineering. Mutations of interfacial disulfide bonds between subunits in the EcCadA decamer, M1 (L89C/L442C), M2 (F102C/L547C), and M3 (V12C/D41C) were chosen. M3 exhibited a 6-fold increase in cadaverine production at pH 10.0. Non-reduced SDS-PAGE analysis demonstrated that the proportion of decamers was greatly increased compared to wild-type enzyme. In addition, molecular dynamics simulations showed that the distance between subunits increased with increased pH, especially in region B. Finally, the fed-batch bioconversion of cadaverine from L-lysine in a 5 L fermenter using M3 by whole-cell catalysis led to 418 g/L cadaverine, which is the highest titer produced to date. This study provided a more efficient enzyme to industrially produce cadaverine with reduced acid use.

Dynamic Changes in the Bacterial Community and Metabolic Profile during Fermentation of Low-Salt Shrimp Paste (Terasi).

Low-salt shrimp paste, or terasi, is an Indonesian fermented food made from planktonic shrimp mixed with a low concentration of salt. Since high daily intake of sodium is deemed unhealthy, reduction of salt content in shrimp paste production is desired. Until now, there is no reported investigation on the bacterial population and metabolite composition of terasi during fermentation. In this study, the bacterial community of terasi was assessed using high-throughput sequencing of the 16S rRNA V3–V4 region. From this analysis, Tetragenococcus, Aloicoccus, Alkalibacillus, Atopostipes, and Alkalibacterium were found to be the dominant bacterial genus in low-salt shrimp paste. GC/MS-based metabolite profiling was also conducted to monitor the metabolite changes during shrimp paste fermentation. Results showed that acetylated amino acids increased, while glutamine levels decreased, during the fermentation of low-salt shrimp paste. At the start of shrimp paste fermentation, Tetragenococcus predominated with histamine and cadaverine accumulation. At the end of fermentation, there was an increase in 4-hydroxyphenyl acetic acid and indole-3-acetic acid levels, as well as the predominance of Atopostipes. Moreover, we found that aspartic acid increased during fermentation. Based on our findings, we recommend that fermentation of low-salt shrimp paste be done for 7 to 21 days, in order to produce shrimp paste that has high nutritional content and reduced health risk.

Effect of various seasoning ingredients on the accumulation of biogenic amines in kimchi during fermentation

This study was aimed at evaluating the effect of basic ingredients (white radish, red pepper powder, garlic, ginger, Welsh onion, fish sauce, and sticky rice porridge) used for kimchi seasoning on the accumulation of biogenic amines (BAs) during kimchi fermentation. Initial accumulation of cadaverine, putrescine, histamine, 2-phenylethylamine, tyramine, and tryptamine occurred mainly owing to fish sauce. Putrescine and tyramine content increased rapidly, reaching 14–15-times the initial values after 7 days of fermentation. Total BA content of kimchi without fish sauce was 42–63% lower than that of kimchi with 5% fish sauce. Moreover, the total BA content of kimchi with 8% red pepper powder added was 25–44% lower than that of kimchi without it. These results show that addition of less fish sauce and more red pepper powder can effectively decrease the total BA content in kimchi.

Influence of bacteriocin-producing Bacillus strains on quality characteristics of fermented soybean product with biogenic amine-forming lactic acid bacteria

This study evaluated the antibacterial activity of bacteriocin produced by Bacillus strains against biogenic amines (BA)-forming lactic acid bacteria (LAB), and the applicability of desirable strains as Bacillus starters for safety and quality improvement of fermented soybean products. The BA-forming ability of the tested LAB in amino acid decarboxylase broth was mostly strain specific rather that species specific. The bacteriocin produced by specific Bacillus strains: Bacillus sp. DB407, Bacillus licheniformis DB612, and Bacillus subtilis DB821 may play a contributory role in the inhibiting the growth of BA-forming strains. In fermented soybean products manufactured using different starter cultures, there was a significant reduction (p < 0.05) in the cell counts of LAB by application of a mixed culture containing B. subtilis DB821, which showed the highest antimicrobial activity. Specifically, B. subtilis DB821 was highly efficient in reducing accumulation of cadaverine, tryptamine, and tyramine produced by Enterococcus faecium D12 and Enterococcus faecalis D51 during soybean fermentation. In conclusion, the bacteriocin-producing Bacillus strains such as Bacillus sp. DB 407, B. licheniformis DB612, and B. subtilis DB821 can be used as a starter culture for the production of BA-controlled soybean products and for the enhancement of the quality and safety of fermented foods.

Accumulation and Transformation of Biogenic Amines and Gamma-Aminobutyric Acid (GABA) in Chickpea Sourdough.

In general, sourdough fermentation leads to an improvement in the technological, nutritional, and sensory properties of bakery products. The use of non-conventional flours with a specific autochthonous microbiota may lead to the formation of secondary metabolites, which may even have undesirable physiological and toxicological effects. Chickpea flours from different suppliers have been used to produce sourdoughs by spontaneous and inoculated fermentations. The content of nutritionally undesirable biogenic amines (BA) and beneficial gamma-aminobutyric acid (GABA) was determined by chromatography. Fenugreek sprouts, which are a rich source of amine oxidases, were used to reduce the BA content in the sourdoughs. Spontaneous fermentation resulted in a high accumulation of cadaverine, putrescine, and tyramine for certain flours. The use of commercial starter cultures was not effective in reducing the accumulation of BA in all sourdoughs. The addition of fenugreek sprouts to the suspension of sourdough with pH raised to 6.5 resulted in a significant reduction in BA contents. Enzymatic oxidation was less efficient during kneading. Baking resulted in only a partial degradation of BA and GABA in the crust and not in the crumb. Therefore, it could be suggested to give more importance to the control of sourdough fermentation with regard to the formation of nutritionally undesirable BA and to exploit the possibilities of their degradation.

바이오제닉 아민 생성 및 분해균의 혼합 배양으로 제조한 청국장의 품질 특성

The objective of this study was to evaluate biogenic amine (BA) formation and degradation abilities of Bacillus strain and lactic acid bacteria (LAB) isolated from meju and doenjang and to determine the microbiological and physicochemical qualities of Cheonggukjang prepared by mixed culture of these strains. Accumulation of cadaverine (421.7 ± 11.0 mg/L) and histamine (628.7 ± 24.1 mg/L) was assessed in the culture media of Bacillus subtilis MJ226 that displayed lysine and histidine decarboxylase activities. No ability to form cadaverine, histamine, putrescine, tryptamine, and tyramine by Lactobacillus acidophilus D11, L. acidophilus D38, Lactobacillus sakei D44, Lactobacillus plantarum D70, which exhibited high BA degradation ability. The amino nitrogen and free amino acid contents were significantly (p&lt;0.05) increased in Cheonggukjang prepared by the mixed culture of LAB (L. sakei D44, L. plantarum D70, or L. pentosus D74) and B. subtilis MJ226, whereas the ammonia nitrogen and BA (cadaverine and histamine) contents were significantly (p&lt;0.05) decreased. Consequently, it was confirmed that BA formation in Cheonggukjang prepared by starter culture of B. subtilis was effectively inhibited by the certain strains of LAB having BA-degrading ability.

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.

Targeting metabolic driving and intermediate influx in lysine catabolism for high-level glutarate production

Various biosynthetic pathways have been designed to explore sustainable production of glutarate, an attractive C5 building block of polyesters and polyamides. However, its efficient production has not been achieved in Escherichia coli. Here, we use E. coli native lysine catabolic machinery for glutarate biosynthesis. This endogenous genes-only design can generate strong metabolic driving force to maximize carbon flux toward glutarate biosynthesis by replenishing glutamate and NAD(P)H for lysine biosynthesis, releasing lysine feedback inhibition, and boosting oxaloacetate supply. We use native transporters to overcome extracellular accumulation of cadaverine and 5-aminovalerate. With these efforts, both high titer (54.5 g L−1) and high yield (0.54 mol mol−1 glucose) of glutarate production are achieved under fed-batch conditions. This work demonstrates the power of redirecting carbon flux and the role of transporters to decrease intermediate accumulation.

Evaluation of psychrophilic, mesophilic, histamine forming bacteria and biogenic amine content in the muscle of mud spiny lobster, Panulirus polyphagus (HERBST, 1793) during ice storage

AbstractThe aim of the present study was to assess the evolution of psychrophilic, mesophilic and histamine forming bacteria along with the accumulation of cadaverine, histamine, putrescine, spermidine, spermine, tryptamine and tyramine during ice storage of mud spiny lobster (Panulirus polyphagus). Total mesophilic, psychrophilic and amine forming bacteria were initially enumerated at 2.62, 2.14 and 2.10 log cfu/g muscle, respectively and reached 7.07, 7.11, and 6.80 log cfu/g muscle, respectively, after 15 days of ice storage. Tryptamine, putrescine and histamine were detected from the 5th day, tyramine, spermidine, and spermine from the 10th day and cadaverine only at the 15th day of storage. Positive correlation of mesophilic and psychrophilic bacteria with tryptamine, putrescine and tyramine was detected. Species belonging to Enterobacter spp., Proteus spp., Klebsiella spp., Citrobacter spp., Photobacterium spp., Serratia spp., and Morganella morganii able to produce histamine, putrescine, cadaverine and tyramine were isolated during storage. The results obtained suggest that P. polyphagus muscle can be stored in ice for short period of time, which may reach 10 days. After the 10th day of ice storage, accumulation of biogenic amines may constitute a potential health hazard.Practical applicationsTo improve our understanding of freshness and bacterial species contribution to biogenic amines production in lobster during ice storage, knowledge of the microecosystem dynamics is necessary. Therefore, we investigated the dynamics of mesophilic, psychrophilic and histamine forming bacteria as well as the evolution of cadaverine, histamine, putrescine, spermidine, spermine, tryptamine and tyramine during ice storage of mud spiny lobster (Panulirus polyphagus). The results of the present study could be useful to assure the safety of lobster by controlling the biogenic amines content.

Rational engineering of ornithine decarboxylase with greater selectivity for ornithine over lysine through protein network analysis

Ornithine decarboxylase (ODC) converts C5 ornithine into C4 putrescine, a monomer for polyamide synthesis. However, ODC also has minor activity towards cell metabolite C6 lysine and yields C5 cadaverine. The accumulation of cadaverine in the reaction solution causes increase in the operational cost of subsequent distillation process for putrescine purification. Here, to increase ODC substrate specificity toward ornithine over lysine, molecular modelling and protein network analysis, specifically k-clique community analysis, around the substrate tunnel were performed. This resulted in a mutant with two-fold increase in substrate specificity (ornithine versus lysine) without losing its original activity towards ornithine (kcat/KM = 61.5 s−1 mM-1), compared to the native enzyme. When this mutant was used for putrescine synthesis, 31.6 g/L putrescine (based on 51.5 g/L ornithine) titer was achieved, while 0.007 g/L (based on 2.57 g/L lysine) cadaverine was produced. This corresponds to four-fold decrease in cadaverine yield compared to the native ODC.

Stimulation of Cadaverine Production by Foodborne Pathogens in the Presence of Lactobacillus, Lactococcus, and Streptococcus spp.

The effect of Lactobacillus plantarum (FI8595), Lactococcus lactis subsp. cremoris MG 1363), Lactococcus lactis subsp. lactis (IL 1403), and Streptococcus thermophilus on cadaverine and other biogenic amine production by foodborne pathogens was investigated lysine decarboxylase broth. Both of lactic acid bacteria and foodborne pathogens used (especially Staphylococcus aureus, E. coli, Lc. lactis subsp. lactis and Lb. plantarum) had an ability to convert aminoacids into biogenic amine. The conversion of lysine into cadaverine was the highest (167.11 mg/L) by Lactobacillus spp. Gram-positive bacteria generally had a greater ability to produce cadaverine with corresponding value of 46.26, 53.76, and 154.54 mg/L for Enterococcus faecalis, S. aureus, and Listeria monocytogenes, respectively. Significant variations on biogenic amine production were observed in the presence of lactic acid bacteria strains (P < 0.05). The role of lactic acid bacteria on biogenic amine production by foodborne pathogens varied depending on strains and specific amine. Cadaverine accumulation by Enterobactericeae was increased in the presence of lactic acid bacteria strains except for St. thermophilus, which induced 2-fold lower cadaverine production by S. Paratyphi A. Lc. lactis subsp. lactis and Lc. lactis subsp. cremoris induced 10-fold higher increases in histamine for E. coli and K. pneumoniae, respectively. Lactic acid bacteria resulted in strong increases in cadaverine production by P. aeruginosa, although remarkable decreases were observed for histamine, spermidine, dopamine, agmatine, and TMA in the presence of lactic acid bacteria in lysine decarboxylase broth . The result of the study showed that amine positive lactic acid bacteria strains in fermented food led to significant amine accumulation by contaminant bacteria and their accumulation in food product may be controlled by the use of proper starters with amine-negative activity.

Production of biogenic amines “in vitro” in relation to the growth phase by Enterobacteriaceae species isolated from traditional sausages

Histidine, lysine, ornithine and tyrosine decarboxylase activities were tested in 79 strains of Enterobacteriaceae (41 of Hafnia alvei, 17 of Serratia liquefaciens, 5 of Enterobacter cloacae, 4 of Citrobacter braakii, 2 of Proteus vulgaris, 2 of Proteus mirabilis, 2 of Providencia stuartii, 2 of Klebsiella terrigena, 1 of Rahnella aquatilis, 1 of Salmonella arizonae, 1 of Citrobacter youngae and 1 of Escherichia coli) isolated from Botillo, a Spanish traditional sausage. In general, the strains were positive for all four activities, with the exception of two strains of H. alvei and the E. coli strain, which did not display histidine decarboxylase activity. The strains of P. mirabilis and P. stuartii did not exhibit any of the four activities tested. Accumulation of putrescine and cadaverine was studied throughout growth of the 75 strains that displayed ornithine and lysine decarboxylase activities. Biogenic amines were produced particularly in the exponential phase, with maximum accumulation occurring after between 12 to 72 h, depending on the biogenic amine and microbial species considered. Maximum accumulation of putrescine varied greatly between species and within the same species, and ranged from 18 mg/l in the R. aquatilis strain to 7325 mg/l in a H. alvei strain. Maximum accumulation of cadaverine varied less than that of putrescine, and ranged from 30 mg/l in the R. aquatilis strain to 1935 mg/l in a S. liquefaciens strain.

Strategies to reduce biogenic amine accumulation in traditional sausage manufacturing

Different strategies in the reduction of biogenic amine accumulation during the manufacture of five European traditional fermented sausages were studied concerning sausage formulation, the increase of sugar in the Italian salame abruzzese reduced the accumulation of cadaverine up to 43%. However, the addition of sugar in the French saucisson did not show a significant amine reduction. The inoculation of a decarboxylase-negative autochthonous starter culture reduced the biogenic amine accumulation in a different manner depending on the species and strain(s). The highest reduction was achieved by Lactobacillus sakei used in the Greek aeros thasou, resulting in a total putrescine reduction and a significant decrease in tyramine (62%) and histamine (71%). In Portuguese chouriços cadaverine reduction was only of 45% when a single strain of Staphylococcus equorum was inoculated, whereas a single strain of L. sakei or a mixture of S. equorum yielded a 75% and 89% of reduction, respectively. In Spanish fuet, a combination of L. sakei CTC6626 plus S. xylosus CTC6013 had only a very slight effect on tyramine reduction (19%) in Spanish fuet, whereas L. sakei CTC494 plus S. xylosus CTC6013 was capable to reduce tyraminogenesis by nearly 50%, suggesting that L. sakei CTC494 was the strain responsible for the additional tyramine reduction.

Relationships between microbial population dynamics and putrescine and cadaverine accumulation during dry fermented sausage ripening

To evaluate the concomitant effects of three technological variables (fermentation temperature, NaCl and glucose added to the meat batter) on diamines (cadaverine, putrescine and histamine) accumulation and microbial changes during ripening of dry fermented sausages. The variables were modulated according to an experimental design and predictive mathematical models were obtained. The models indicated that the sausages were characterized by low histamine amount independently on the applied conditions. In contrast, putrescine and cadaverine accumulation was considerable and significantly affected by the three variables. The microbial population dynamics suggest that lactic acid bacteria (LAB) and microstaphylococci are favoured by increasing glucose concentration until 0.7 g kg(-1), while Enterobacteriaceae are negatively influenced by NaCl concentration and, to a lesser extent, by fermentation temperature. Data obtained showed a relationship between Enterobacteriaceae growth and cadaverine and putrescine accumulation in sausages during ripening. The conditions more favourable for LAB and microstaphylococci induced a reduced growth of Enterobacteriaceae with a consequent reduced accumulation of putrescine and cadaverine. The use of systematic experimental designs allows to individuate the technological conditions suitable to keep the aminogenic microflora under control, thus reducing the risk of diamines production during traditional fermented food manufacture.

Adaptive functions of Escherichia coli polyamines in response to sublethal concentrations of antibiotics

Escherichia coli exposure to sublethal antibiotic concentrations induced an increase in cell polyamine contents. Maximum accumulation of putrescine and spermidine in response to antibiotics-induced oxidative stress preceded the increment of cadaverine, the content of which was dependent on the rpoS expression level and reached the maximum in response to fluoroquinolones. The polyamine positive modulating effects on rpoS expression increased in the following order: cadaverine-putrescine-spermidine. The reason for cadaverine accumulation was the increase in activities of lysine decarboxylases CadA and Ldc. High cadaverine accumulation in the cells exposed to fluoroquinolones and cephalosporins resulted in the reduction of porin permeability; so it was considered as a response aimed at cell protection against antibiotic penetration into the cell. Netilmycin, unlike other antibiotics, did not substantially affect the lysine decarboxylase activity and cellular polyamine pools.

SAHA induces caspase‐independent, autophagic cell death of endometrial stromal sarcoma cells by influencing the mTOR pathway

Endometrial stromal sarcomas are rare and molecular mechanisms involved in their pathogenesis are poorly understood. Covalent modifications of histone proteins, in particular de/acetylation of lysine residues, play an important role in the regulation of gene transcription in normal and neoplastic cells, but there are only limited data about these processes in solid mesenchymal tumours. We treated endometrial stromal sarcoma cells (ESS-1) and non-malignant human endometrial stromal cells (HESCs) with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor. SAHA was able to mediate the cell cycle and expression of genes related to the malignant phenotype of endometrial stromal tumours, eg p21(WAF1) and HDAC7. SAHA led to dose-dependent differentiation and death of ESS-1 cells but not of HESCs. Exposure of HESCs to SAHA resulted only in slightly decreased cell proliferation. SAHA also increased the p21(WAF1) expression and caused significant changes in the cell cycle by inhibiting the G1/S transition in ESS-1 cells. Recovery experiments indicated that these changes became irreversible when the tumour cells were treated with SAHA for longer than 24 h. In our experimental system, not apoptotic but autophagic processes were responsible for the cell death. Monodansyl cadaverine accumulation in treated ESS-1 cells and decreased expression of the mTOR and phospho-S6 ribosomal protein (S6rp) additionally supported this observation. Taken together, our study indicates that HDACs might be considered as potential drug targets in the therapy of stromal sarcomas and that SAHA might be a promising therapeutic agent for endometrial stromal sarcoma.

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.

NaCl- and ethylene-dependent cadaverine accumulation and its possible protective role in the adaptation of the common ice plant to salt stress

The accumulation of free polyamines is very important for plant resistance to abiotic stresses. In this study, a putative defensive role of free cadaverine (Cad) in the halophyte Mesembryanthemum crystallinum L. (the common ice plant) was studied. Under salinity conditions (500 mM NaCl), Cad accumulation was accompanied by enhanced ethylene (Eth) production in true leaves of the common ice plants. The involvement of Eth in Cad production was confirmed by detached leaf treatment with exogenous Eth. In experiments with etiolated seedlings of the common ice plants and Eth-insensitive arabidopsis mutant ( ein4), it was shown that the interactions between Cad and Eth under stress conditions were especially essential for cell elongation. However, a NaCl-induced increase in the Cad content and Eth production was not related to expression of stress-induced PEPC gene (at the mRNA level). DNA protection by Cad from oxidative degradation in vitro in the hydroxyl radical-generating system was demonstrated. This polyamine was supposed to act as a free radical scavenger. A possible interaction between Eth production and Cad accumulation and its relevance to plant stress–adaptation are discussed.