Foliar sprays of three plant resistance inducers, including chitosan (CH), potassium sorbate (PS) (C₆H₇kO₂), and potassium bicarbonates (PB) (KHCO₃), were used for resistance inducing against Erysiphe cichoracearum DC (powdery mildew) infecting okra plants. Experiments under green house and field conditions showed that, the powdery mildew disease severity was significantly reduced with all tested treatments of CH, PS, and PB in comparison with untreated control. CH at 0.5% and 0.75% (w/v) plus PS at 1.0% and 2.0% and/or PB at 2.0% or 3.0% recorded as the most effective treatments. Moreover, the highest values of vegetative studies and yield were observed with such treatments. CH and potassium salts treatments reflected many compounds of defense singles which leading to the activation power defense system in okra plant. The highest records of reduction in powdery mildew were accompanied with increasing in total phenolic, protein content and increased the activity of polyphenol oxidase, peroxidase, chitinase, and β-1,3-glucanase in okra plants. Meanwhile, single treatments of CH, PS, and PB at high concentration (0.75%, 2.0%, and/or 3.0%) caused considerable effects. Therefore, application of CH and potassium salts as natural and chemical inducers by foliar methods can be used to control of powdery mildew disease at early stages of growth and led to a maximum fruit yield in okra plants.
Abelmoschus* ; Bicarbonates ; Catechol Oxidase ; Chitinase ; Chitosan* ; Fruit ; Peroxidase ; Phenol ; Plants* ; Potassium* ; Salts* ; Sorbic Acid

cis, cis-muconic acid (MA) is an important platform chemical. Now, majority of reported engineered strains are genetically instable, the exogenous genes are expressed under the control of expensive inducer and the components of their fermentation medium are complex, thus large-scale microbial production of MA is limited due to the lack of suitable strains. Hence, it is still necessary to construct novel high-performance strain that is genetically stable, no induction and grows in simple inorganic fermentation medium. In this study, after 3 exogenous genes (aroZ, aroY, catA) for biosynthesis of MA were integrated into previously constructed 3-hydroshikimate producing Escherichia coli WJ060 strain and combinatorially regulated with 3 constitutive promoters with different strengths, 27 engineered strains were constructed. The best engineered strain, E. coli MA30 could produce 1.7 g/L MA in the simple inorganic fermentation medium without induction. To further enhance the production capacity of MA, the mutant library of E. coli MA30 was constructed by genome replication engineering and screened via high-throughput assay. After two-round screening, the new strain, E. coli MA30-G2 with improved production of MA was obtained, and the titer of MA increased more than 8%. Under the condition of 5 L fed-batch fermentation, E. coli MA30-G2 could produce about 11.5 g/L MA. Combinatorial regulation and high-throughput screening provide important reference to microbial production of other bio-based chemicals.
Escherichia coli ; metabolism ; Fermentation ; Industrial Microbiology ; Metabolic Engineering ; Microorganisms, Genetically-Modified ; Promoter Regions, Genetic ; Sorbic Acid ; analogs & derivatives ; metabolism

OBJECTIVETo establish a method for simultaneously determining the urinary concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG), trans, trans-muconic acid (tt-MA), and S-phenylmercapturic acid (S-PMA) in subjects exposed to benzene.

METHODSAfter being purified by a solid-phase extraction column, the urine samples were transferred to a liquid chromatography-mass spectrometry system, and the concentrations of 8-OHdG, tt-MA, and S-PMA were determined by external standard method. A C18 reversed-phase column was used as the chromatographic column, and methanol/acidic ammonium formate solution was used as the mobile phase for gradient elution. The mass spectrometer was operated in a multi-reaction monitoring mode.

RESULTSFor tt-MA, the calibration curves were linear in the range of 10-1000 µg/L, and the recovery rates were over 90% (relative standard deviation (RSD) < 3%) at spiked levels of 50 µg/L and 500 µg/L. For S-PMA and 8-OHdG, the calibration curves were linear in the range of 1-100 µg/L, and the recovery rates were over 85% (RSD < 5%) at spiked levels of 5 µg/L and 50 µg/L.

CONCLUSIONThis determination method meets the requirement of Biological materials-

METHODSof monitoring-Guide of development (WS/T 68-1996) and can be used for simultaneous determination of 8-OHdG, tt-MA, and S-PMA in urine.

Acetylcysteine ; analogs & derivatives ; urine ; Benzene ; poisoning ; Chromatography, Liquid ; methods ; Deoxyguanosine ; analogs & derivatives ; urine ; Humans ; Mass Spectrometry ; Occupational Exposure ; prevention & control ; Sorbic Acid ; analogs & derivatives ; metabolism

Promoter is one of important elements for gene expression and regulation. In the construction of recombinants for metabolic engineering and synthetic biology, it is necessary to have the promoters with varying strengths for fine-tuning metabolic pathway to reach the metabolic balance, decrease the accumulation of intermediate and increase the production of target metabolite. However, the natural promoters available are not completely suitable for fine-tuning metabolic pathway due to discrete strength, lack of versatility and standardization. To deal with this problem, in this study, a new 88 bp synthetic promoter, which contains the typical -35 box, -10 box as well as ribosome bind site, was designed. Then, the promoter library was constructed by introducing some degenerate base pairs in the sequence of 6 bp in the upstream of the initial transcription site and 14 bp in spacer region between -35 and -10 box. 720 promoters with varying strengths were screened out from a library of more than 5 000 clones via the expression of red fluorescent protein mCherry under the control of the synthetic promoter. The sequence analysis based on 35 promoters with varying strengths showed the promoters with varying strengths are base preference. The purine bases in -13 site and pyrimidine bases in the transcriptional initiation sequence are of high frequency; the purine and pyrimidine bases are of the similar frequency in the spacer sequence between -35 and -10 box in strong promoter. In the end, five characterized promoters with varying strengths were selected to tune the synthetic pathway of cis,cis-muconic acid in Escherichia coli. The results showed that the promoters with varying strengths can regulate the production of cis,cis-muconic acid and the accumulation of the intermediate catechol.
Base Sequence ; Escherichia coli ; genetics ; metabolism ; Gene Expression Regulation, Bacterial ; Genes, Bacterial ; Metabolic Engineering ; methods ; Molecular Sequence Data ; Promoter Regions, Genetic ; Sorbic Acid ; analogs & derivatives ; metabolism

OBJECTIVES: Automobile exhaust gases contain benzene and toluene, which are excreted in human urine as trans,trans-muconic acid and hippuric acid, respectively. Sorbic acid and benzoic acid, used as food preservatives, are also metabolized into trans,trans-muconic acid and hippuric acid in the human body. The purpose of this study is to estimate the level of benzene and toluene exposure according to the commuting mode and duration, residential environment, and preservative-added foods intake in university students who are not occupationally exposed to benzene or toluene. METHODS: Spot urine samples were collected from 211 university students who had no occupational exposure to volatile organic compounds. Information about their smoking history, residence type, traffic environments, commuting mode and duration, and their intake of bottled or canned food or beverages was gathered through a self-administered questionnaire. Urinary concentrations of trans,trans-muconic acid and hippuric acid were measured and statistically correlated to the individual's life style factors. RESULTS: There was no significant difference in the urinary concentrations of trans,trans-muconic acid or hippuric acid according to the smoking history. Mean urinary concentration of hippuric acid in females was higher than that found in males. Subjects living in districts with a population density of 1,000~4,999 people/km2 showed the highest urinary hippuric acid level; individuals living in cities of 5,000~9,999 people/km2 population density were next. The mean urinary trans,trans-muconic acid concentration was higher in students who were living where traffic jams are common compared to those who did not, and in subjects whose residence were within 149 m from a 4-lane road compared to those whose residence was not. However, neither mode nor duration of the commute showed any effect on the urinary trans,trans-muconic acid or hippuric acid concentrations of the students. Urinary hippuric acid levels increased when consuming canned fruit or canned coffee, and urinary trans,trans-muconic acid levels increased when consuming fruit juices or pickled radishes. CONCLUSIONS: The inhalation of vehicle exhaust and the ingestion of canned or pickled food may increase urinary hippuric acid and trans,trans-muconic acid levels in individuals who are not occupationally exposed to benzene or toluene.
Benzene ; Benzoic Acid ; Beverages ; Coffee ; Eating ; Female ; Food Preservatives ; Food, Preserved ; Fruit ; Gases ; Hippurates ; Human Body ; Humans ; Inhalation ; Life Style ; Male ; Occupational Exposure ; Occupations ; Population Density ; Questionnaires ; Smoke ; Smoking ; Sorbic Acid ; Toluene ; Transportation ; Vehicle Emissions ; Volatile Organic Compounds

OBJECTIVES: In this study, we summarized the External Quality Assessment Scheme (EQAS) for the biological monitoring of occupational exposure to toxic chemicals which started in 1995 and continued until a 31st round robin in the spring of 2010. The program was performed twice per year until 2009, and this was changed to once a year since 2010. The objective of the program is to ensure the reliability of the data related to biological monitoring from analytical laboratories. METHODS: One hundred and eighteen laboratories participated in the 31st round robin. The program offers 5 items for inorganic analysis: lead in blood, cadmium in blood, manganese in blood, cadmium in urine, and mercury in urine. It also offers 10 items for organic analysis, including hippuric acid, methylhippuric acid, mandelic acid, phenylglyoxylic acid, N-methylformamide, N-methylacetamide, trichloroacetic acid, total trichloro-compounds, trans,trans-muconic acid, and 2,5-hexanedione in urine. Target values were determined by statistical analysis using consensus values. All the data, such as chromatograms and calibration curves, were reviewed by the committee. RESULTS: The proficiency rate was below 70% prior to the first round robin and improved to over 90% for common items, such as PbB and HA, while those for other items still remained in the range of 60-90% and need to be improved up to 90%. CONCLUSION: The EQAS has taken a primary role in improving the reliability of analytical data. A total quality assurance scheme is suggested, including the validation of technical documentation for the whole analytical procedure.
Acetamides ; Cadmium ; Calibration ; Consensus ; Dietary Sucrose ; Environmental Monitoring ; Formamides ; Glyoxylates ; Hexanones ; Hippurates ; Mandelic Acids ; Manganese ; Occupational Exposure ; Songbirds ; Sorbic Acid ; Trichloroacetic Acid

OBJECTIVE: Recent researches suggest that trans,trans-muconic acid (t,t-MA) would be an adequate metabolic biomarker for low-level benzene exposure. Few study have investigated the association between the t,t-MA and platelet count, and this is the primary aim of this study. METHODS: From May 2004 to June 2004, 326 chemical factory workers took part in a questionnaire survey and they underwent urinary t,t-MA and CBC assessment. The questionnaire covered general aspects of health and the occupational and smoking histories. Statistical analyses of outcomes were performed using SPSS 14.0 for Windows. RESULTS: The subjects' urinary t,t-MA concentration (geometric mean and geometric standard deviation) was 0.28 mg/g creatinine (2.62). No significant differences between different occupations among the chemical workers were found. The urinary t,t-MA concentrations in the smokers and non-smokers were 0.32 mg/g creatinine (2.44) and 0.25 mg/g creatinine (2.77) respectively, and the difference was statistically significant (p<0.05). There was no significant difference in the platelet count based on occupation and the smoking history. There was significant correlation between log(platelet) and log(t,t-MA)(r=-0.116 p=0.039). The regression equation log(platelet) = -0.002xAge + [-0.029xlog(t,t-MA)] + 2.436, R2=0.032, was calculated from linear regression analysis with log(platelet) as the dependent variable. Cross-tabulation between 2 subgroups that were divided by the 90-percentile level of the t,t-MA (0.819 mg/g creatinine), and 2 subgroups that were divided by the 10-percentile level of the platelet count (175,000) was conducted. Higher distribution in subgroup with platelet count below 175,000 was demonstrated in the subgroup with a urinary t,t-MA above the 90-percentile, with an odds ratio of 3.01. CONCLUSIONS: The study may be limited by not taking into account factors such as smoking quantity and sorbic acid, which may confound urinary the t,t-MA concentration as well as medication and infection that may affect the platelet count. Yet it is meaningful that the correlation between the urinary t,t-MA concentration and the platelet count was found through linear regression analysis and the chi-square test, and further, this outcome may be used as a basis for a study to establish the acceptable limit of urinary t,t-MA in Korea.
Benzene ; Blood Platelets ; Creatinine ; Korea ; Linear Models ; Occupations ; Odds Ratio ; Platelet Count ; Questionnaires ; Smoke ; Smoking ; Sorbic Acid

Chromatography, Reverse-Phase ; methods ; Humans ; Sorbic Acid ; analogs & derivatives ; analysis ; Urinalysis ; methods

OBJECTIVES: This study was performed to estimate the exposure to benzene, one of the most serious health hazards, in four phases of a turnaround in a petrochemical company, and to evaluate the suitability of trans,trans-muconic acid (tt-MA) to act as a biomarker of exposure to low benzene levels. METHODS: tt-MA was determined in 152 urine samples collected in 4 phases ('before daily work', 'after daily work', 'purge', and 'inspection' of turnaround work) from 19 exposed workers involved in turnaround work and 19 clerical workers. The ambient benzene levels were monitored simultaneously during the 'purge' process of turnaround work in the exposed group. RESULTS: The median urinary tt-MA for the 4 phases was 0.046 mg/L, 0.082 mg/L, 0.507 mg/L, and 0.468 mg/L in the exposed group and 0.050 mg/L, 0.065 mg/L, 0.269 mg/L, and 0.331 mg/L in the clerical workers, respectively. The median urinary tt-MA for the exposed group was significantly higher than that of the clerical workers during the purge process (P<0.05). In the exposed group, median urinary tt-MA for the 'before daily work' phase was significantly lower than that of the other three phases (P<0.05). Even in the clerical workers, the urinary tt-MA level for the 'before daily work' phase was significantly lower than that of the turnaround (P<0.05). There was a very significant correlation between urinary tt-MA levels and ambient benzene levels (r(s) = 0.795, P<0.01). CONCLUSION: The turnaround process increased the benzene exposure for all workers, even the clerical workers, in a petrochemical company handling benzene. Urinary tt-MA was found to be suitable as a biomarker for the exposure to low-level benzene.
Benzene ; Handling (Psychology) ; Hazardous Substances ; Plants ; Sorbic Acid

Beef luncheon meat is one of the most popular meals in several countries in the world including Egypt. Thirty one fungal species and 3 species varieties were recovered from 30 samples of beef luncheon meat collected from different supermarkets in Qena. Alternaria, Aspergillus, Emericella, Mucor, Mycosphaerella, Penicillium and Rhizopus were the most common genera on the two types of media. From the above genera, the most prevalent species were Alternaria alternate, Aspergillus flavus, A. fumigatus, A. niger, A. terreus, Emericella nidulans, Mucor racemosus, Mycosphaerella tassiana, Penicillium chrysogenum and Rhizopus stolonifer. Screening of fungi for their abilities to produce lipase enzyme showed that, ten isolates represented 32.26% of total isolates appeared high lipase production, while sixteen isolates (51.61%) were moderate and 5 isolates (16.13%) were low producers. Aspergillus niger, Fusarium oxysporum and Nectria haematococca produced the highest amount of lipase enzyme, so these fungi were used in further studies. The incorporation of five food preservatives (Disodium phosphate, sodium benzoate, citric acid, potassium sorbate and sodium citrate) individually in the culture medium of lipase production exhibited an inhibitive effect on the mycelial growth and enzyme production by Aspergillus niger, Fusarium oxysporum and Nectria haematococca.
Alternaria ; Aspergillus ; Aspergillus flavus ; Aspergillus niger ; Citric Acid ; Egypt ; Emericella ; Food Preservatives ; Fungi ; Fusarium ; Lipase ; Mass Screening ; Meals ; Meat ; Mucor ; Nectria ; Niger ; Penicillium ; Penicillium chrysogenum ; Rhizopus ; Sodium ; Sodium Benzoate ; Sorbic Acid