GacA/S signaalraja puudumine mõjutab raaminihke- ja asendusmutatsioonide tekkesagedust Pseudomonas putida KT2440 tüves

GacA/GacS two-component system can be found in Gram-negative bacteria, including enteric bacteria and Pseudomonas. gacS gene encodes for a membrane-bound sensor kinase GacS, whereas a transcriptional response regulator GacA is encoded by gacA gene. The aim of this thesis was to investigate whether the inactivation of the GacA/GacS two-component system could affect mutation frequency in Pseudomonas putida. Two test systems were employed for measuring mutation frequency: chromosomal RifR assay and a plasmidial test system based on lactose degradation. RifR phenotype of bacteria is a result of mutations that decrease the affinity of rifampicin binding to the β subunit of RNA polymerase. This makes this enzyme insensitive to rifampicin. The second test system is based on the monitoring mutations in lacZ gene encoding for β-galactosidase, which turns the tester strains from Lac- to Lac+ phenotype. Usage of both test systems revealed that the inactivation of the gacA gene elevates mutation frequency in P. putida. In estonian: GacA/GacS kahekomponendiline süsteem on kirjeldatud erinevates Gram negatiivsetes bakteriliikides, kuhu kuuluvad ka enterobakterid ja erinevad Pseudomonase liigid. Geen gacS kodeerib membraan-seoselist sensorkinaasi GacS ning transkriptsiooni regulaator GacA, mis saab signaali GacS-lt, on kodeeritud geeni gacA poolt. Käesoleva bakalaureusetöö eesmärgiks oli välja selgitada, kas GacA/GacS süsteemi inaktiveerimine mõjutab bakteris Pseudomonas putida mutatsioonisagedust. Mutatsioonisageduse mõõtmiseks kasutati kahte testsüsteemi: kromosomaalset RifR süsteemi ja plasmiidset laktoosi lagundamisel põhinevat Lac+ süsteemi. RifR fenotüübiga bakterites on tekkinud mutatsioonid, mis vähendavad rifampitsiini seondumist RNA polümeraasi β-subühikuga, muutes sel viisil ensüümi rifampitsiini suhtes tundetuks. Teine testsüsteem põhineb β-galaktosidaasi kodeerivas geenis lacZ tekkivate mutatsioonide tuvastamisel, mis võimaldavad Lac- testertüvedel hakata lagundama laktoosi (Lac+ reversioon). Töö tulemustena selgus, et gacA geeni inaktiveerimine bakteris P. putida põhjustas mutatsioonisageduse suurenemist mõlemate testsüsteemide rakendamisel

Using the best - worst scale to assess the relative impact of these behaviors on other passengers on the same flight: The disruptive passenger behavior

A method called the best-worst scaling method is proposed to overcome these problems by asking respondents to make tradeoffs among the variables being assessed. This paper raises issues in respect of supplementing and developing a block of disruptive behaviors exhibited by passengers during flights and assesses the impact of these behaviors on other passengers. To illustrate the proposed method and evaluate its performance, we surveyed 240 passengers, and data from 203 survey samples were analyzed. The data analysis results revealed three behaviors that were considered the most disruptive, including (1) Threatening and causing distress, (2) Harassment and disrupting public order, and (3) Creating unsanitary conditions. This can be considered a suitable explanation with the high safety requirements of the air transport service, and the context of high expectation of post-covid hygiene and epidemiology

Application of Integrated-Weight Water Quality Index in Groundwater Quality Evaluation

Groundwater is one of the most crucial freshwater resources in many parts of the world. However, the growth of the population and different economic activities have negatively impacted groundwater quality. This study aims to assess the groundwater quality in An-Giang province, Vietnam, from 2017–2020 and investigate its suitability for drinking via a new integrated-weight water quality index (IWQI). The samples were collected at thirteen wells in dry and rainy seasons and analyzed for eleven physicochemical parameters, including pH, total dissolved solids (TDS), total hardness, nitrate (NO3ˉ), ammonium (NH4+), iron (Fe), manganese (Mn), arsenic (As), mercury (Hg), lead (Pb), and coliform. These values were compared to the Vietnamese standard. The entropy weight method and the Criteria Importance Though Inter-criteria The correlation weighting method was integrated to compute the weights in IWQI. The results showed that NH4+and coliform concentrations were consecutively higher than the standard over the study period. No detection of As, Hg, and Pb concentrations in groundwater was in 2019 – 2020. There were significant statistical differences between parameters from 2017–2020 in the dry and rainy seasons. The results of IWQI revealed that about 40% of the total samples in 2020 were categorized as unsuitable for drinking. IWQI values range from 72 to 7973 in 2020, 12 to 3020 in 2019, 21 to 1115 in 2018, and 53 to 2246 in 2017. Most samples with high IWQI values are located near the burial pits of African fever-infected swine. The findings of this study could provide further information about the changes in groundwater quality from 2017–2020 in An Giang province, Vietnam, and the IWQI method can be proposed for other studies to evaluate groundwater quality effectively. Doi: 10.28991/CEJ-2022-08-11-020 Full Text: PD

Health Risk Assessment for the Exposure of Workers to BTEX at the Gasoline Stations

The study was conducted to assess the health risks of workers due to exposure to toxic gases including benzene, toluene, ethylbenzene, m, p-xylene, o-xylene, formaldehyde and acetaldehyde at gasoline retail stations. In this study, data on the  concentrations of the toxic gases were collected from the previously published studies in the qualified scientific journals. The health risk assessment was followed by the process of the United States Environment Protection Agency (U.S. EPA). The results show that the concentrations of benzene, toluene, ethylbenzene, m, p-xylene, o-xylene, formaldehyde, and acetaldehyde were in the range of 12.40 - 357.5, 12.47 - 574.17, 2.05 - 156.5, 4.57 - 218, 2.36 - 77.04, 3.64 - 153.93 and 1.27- 27.83 µg/m3 , respectively. Life time cancer risk for gasoline station workers due to exposure to benzene, ethylbenzene, formaldehyde, and acetaldehyde was calculated in the ranges of 2.13x10-5 - 6.14x10-4 , 4.96x10-7 - 3.79x10-5 , 4.81x10-6 - 2.03x10-4 , and 7.99x10-7 - 1.75x10-5 , respectively. For non-carcinogenic  compounds, the hazard index due to benzene, toluene, m, p-xylene, o-xylene were respectively in the range of 0.13 - 3.81, 7.97x10-4 -  0.04, 0.01 - 0.70 and 0.01 - 0.25. The findings revealed that there is high risk of cancer and non-cancer for the workers working at the gasolines stations if they are not taking good preventive measures. The calculation showed that the limit levels of benzene, toluene, ethylbenzene, xylene, formaldehyde and acetaldehyde should be reduced to 5.82x10-4 , 15.64, 4.13x10- 3 , 0.31, 7.57x10-4 and 1.59x10-3 mg/m3 , respectively to meet the safety levels for the workers at the gasoline stations. Keywords: benzene, toluene, ethylbenzene, xylene, formaldehyde, acetaldehyde, life-time cancer risk, healt

Physico-chemical properties of fourteen popular cocoa bean varieties in Dongnai-highland Vietnam

Cocoa (Theobroma cacao L.) is a major, crucial economic, global crop and has been maintained several nutritional benefits. The exporting volume of Vietnamese cocoa bean is increasing in the world cocoa trade. The beans of fourteen popular cocoa varieties that are commonly cultivated in Trang Bom (Dong Nai, Vietnam) were characterized for their physico-chemical qualifications on the background of post-fermented cocoa beans and dehydration in the region of Trang Bom-Dong Nai. The physical properties were determined based on mass ratio and bean’s dimension (lengh, width and thickness) as well as chemical (proximate) composition (total crude protein, ash, moisture, and lipid). These values were analysed using AOAC methods. The largest-size beans were found for the TD8 variety (1.5 g of mass, 25.02 mm of length, 14.28 mm of width and 7.96 mm of thickness). The moisture content of the cocoa beans was in the range between 5.64 and 6.99 (% wb) and the ash content in the range between 3.67% and 2.47% (wb). Noticeably, the fat content ratio (the most important value of cocoa bean) found in 8 varieties (TD1, TD2, TD5, TD9, TD11, TD12, TD13, TD14) was over 50%, thus these varieties are worthy chemical component especially for exported cocoa bean and industrized cultivation (extending the cultivation producing area)