Cooperative Interaction between Acid and Copper Resistance in Escherichia coli

( Yeeun Kim ),( Seohyeon Lee ),( Kyungah Park ),( Hyunjin Yoon ) 한국미생물생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.5

The persistence of pathogenic Escherichia coli under acidic conditions poses a serious risk to food safety, especially in acidic foods such as kimchi. To identify the bacterial factors required for acid resistance, transcriptomic analysis was conducted on an acid-resistant enterotoxigenic E. coli strain and the genes with significant changes in their expression under acidic pH were selected as putative resistance factors against acid stress. These genes included those associated with a glutamatedependent acid resistance (GDAR) system and copper resistance. E. coli strains lacking GadA, GadB, or YbaST, the components of the GDAR system, exhibited significantly attenuated growth and survival under acidic stress conditions. Accordantly, the inhibition of the GDAR system by 3- mercaptopropionic acid and aminooxyacetic acid abolished bacterial adaptation and survival under acidic conditions, indicating the indispensable role of a GDAR system in acid resistance. Intriguingly, the lack of cueR encoding a transcriptional regulator for copper resistance genes markedly impaired bacterial resistance to acid stress as well as copper. Conversely, the absence of YbaST severely compromised bacterial resistance against copper, suggesting an interplay between acid and copper resistance. These results suggest that a GDAR system can be a promising target for developing control measures to prevent E. coli resistance to acid and copper treatments.

Prevalence and Mechanisms of Low Level Quinolone Resistance among Non-Typhoidal Salmonella Isolates from Human and poultry/Livestock in Korea: Usefulness of Nalidixic Acid Resistance Test

황인숙,송준영,김우주,정혜원,김무상,정희진 대한감염학회 2010 Infection and Chemotherapy Vol.42 No.4

Background: Non-typhoidal Salmonella (NTS) are important commensal microorganisms. We intended to investigate the prevalence and mechanisms of nalidixic acid resistance among NTS isolated from human and poultry/livestock. Methods: A total of 151 Salmonella isolates (36 human and 115 livestock isolates,respectively) was tested for the Minimum inhibitory concentrations (MICs) of nalidixic acid, together with serotyping. As for the nalidixic acid resistant isolates,further studies were taken: MICs of ciprofloxacin, mutation analysis of gyrA and parC genes, and organic solvent tolerance test. Results: Eighty-four isolates of 151 human and livestock isolates were resistant to nalidixic acid. The prevalence of nalidixic acid resistance and was 13.9% (5of 36 isolates) in human isolates and 68.7% (79 of 151 isolates), in the livestock isolates respectively. Among 84 nalidixic acid-resistant isolates, the The prevalence of ciprofloxacin resistance in livestock isolates was 24.1% (1 resistant and 18intermediate of 79 strains), but no ciprofloxacin resistance was found in 5 human isolates. Among 65 nalidixic acid resistant, ciprofloxacin-susceptible isolates, 3(60%, of 5 human isolates) and 60 (100%, all livestock isolates) showed low level fluoroquinolone resistance (ciprofloxacin MIC, 0.125-1.0 μg/μL). Six types of point mutations were found in the analysis of DNA sequencing of the gyrA gene in the 84isolates; 75 isolates showed point mutations on amino acid Ser 83 and/or Asp 87. On the other hand, no point mutation was found from the parC genes. Forty-seven nalidixic acid resistant isolates showed tolerance to organic solvents. Conclusions: Nalidixic acid resistance was a good marker of low level fluoroquinolone resistance. As for the severe NTS infection, MIC test for nalidixic acid would be required.

Listeria monocytogenes Scott A 의 성장과 열저항성에 미치는 유기산의 영향

이신호,조현순,김순희 대구효성가톨릭대학교 식품과학연구소 1994 식품과학지 Vol.6 No.-

유기산(acetic, tartaric, propionic, citric 그리고 lactic acid)에 의한 L. monocytogenes Scott A의 성장과 열저항성에 미치는 영향을 겸토한 결과 각 유기산 0.1%를 첨가한 경우 배양 48시간 동안 대조구에 비해 뚜렷한 성장억제현상이 관찰되었으며, 배양중 pH는 대수적 증식 말기인 12시간째 대조구 5.17, propionic acid첨가구 5.57인 반면 그외 유기산 첨가구의 pH는 4.60~4.88였다. 0.2%의 유기산을 첨가한 경우 acetic acid 또는 propionic acid 첨가구에서는 배양 48시간 동안 성장이 거의 일어나지 않았다. 각 유기산으로 pH 5.0과 6.0으로 조절한 TSB를 기질로 사용하여 65℃에서 1분간 처리하여 열저항성을 비교한 결과 pH 5.0에서는 유기산의 종류에 따라 열처리 효과는 상이하였으며, citric acid 또는 propionic acid 처리구의 log reduction이 각각 1.56, 1.79로 열처리 효과가 가장 높았으며 pH 6.0에서 열처리효과는 유사한 경향을 나타내었다. 각 유기산을 사용하여 pH 5.0과 6.0으로 조절한 0.1M sodium phosphate를 열처리 기질로 사용한 경우 pH 5.0에서 propionic acid처리구와 lactic acid의 처리구의 열처리효과가 가장 높았다. TSB에 유기산을 첨가하여 pH 5.0으로 조절한 후 65℃에서 adherent microlony의 열저항성을 검토한 결과 propionic acid처리구의 log reduction은 1.21을 나타내어 열처리효과가 가장 높은 것으로 관찰되었으며, adherent microcolony는 planktonic cell에 비해 강한 열저항성을 나타내었다. The effects of organic acids on growth and heat resistance of Listeria monocytogenes Scott A were investigated. The growth of L. monocytogenes was inhibited in Tryptic Soy Broth(TSB) with 0.1 or 0.2% of acetic, tartic, propionic, citric and lactic acid at 35℃, respectively. The growth of L. monocytogenes did not occur in TSB with 0.2% of acetic acid or propionic acid during 48h of incubation. The heat resistance of L. monocytogenes was affected by kind of organic acid, pH and heating substrate. L. monocytogenes showed more heat resistant in TSB with various organic acids than in 0.1M sodium phosphate with the same organic acids. Heat resistance decreased as pH of heating substrate decreased. Surface-adherent microcolony was more heat resistant than planktonic cell of L. monocytogenes. Propionic and lactic acids more affected on heat resistance of L. monocytogenes than acetic, tartaric and citric acids.

Development of a Sunscreen Stick Formulation which is Water Resistant but Easily Washable

Choi, Minsung,Song, Seungjin,Kang, Nae-Gyu Society of Cosmetic Scientists of Korea 2020 Korean journal of cosmetic science Vol.2 No.1

The aim of this study is to develop a sunscreen stick formulation technology with excellent water resistance and washability. Consumers' needs for sunscreen products are diversifying. Water resistance and ease of washing are both important factors in sunscreen products. However, it is difficult to develop a sunscreen formulation that satisfies these two factors at the same time, because these two elements are in conflict. Fatty acid has a hydrophobic property against the water with low or neutral pH, but when it contacts with soapy water which has high pH, saponification occurs and the fatty acids become surfactants and can be dispersed in the water. Using the reaction characteristics of fatty acids, we can make sunscreen that is highly resistant to water or sweat, but is only selectively removed from soapy water. We found that the sunscreen stick containing fatty acids had better water resistance and washability than the sunscreen sticks without fatty acid. The sunscreen stick containing fatty acids showed a tendency to improve water resistance by scattering ultraviolet rays of long wavelength area by forming insoluble precipitation with divalent ions in tap water after immersion. In addition, an increase in the fatty acid content tended to also increase the ease of cleaning the sunscreen stick. Solid fatty acid was advantageous in improving water resistance than liquid fatty acid, but there was no difference between solid fatty acids and liquid fatty acid in washability. When it comes to stability, the sunscreen stick using liquid fatty acids maintained a high hardness and melting point, and showed no sweating. Based on this study, it is possible to develop an easy washable sunscreen stick formulation technology that has excellent water resistance but is selectively removed only in soapy water.

Effect of salt addition on acid resistance response of <i>Escherichia coli</i> O157:H7 against acetic acid

Bae, Young-Min,Lee, Sun-Young Elsevier 2017 FOOD MICROBIOLOGY Vol.65 No.-

<P><B>Abstract</B></P> <P>A combination of salt and acid is commonly used in the production of many foods, such as pickles and fermented foods. However, in our previous studies, addition of salt significantly reduced the inhibitory effect of acetic acid against <I>E. coli</I> O157:H7 in laboratory media and pickled cucumbers. Therefore, this study was conducted to determine the effect of salt addition on the acid resistance (AR) response of <I>E. coli</I> O157:H7 after treatment with acetic acid. The combined effect of acetic acid and salt showed different results depending on media tested. Organic compounds such as yeast extract and tryptone were required to observe the antagonistic effect of salt and acetic acid in combination. However, use of an <I>rpoS</I> mutant or addition of chloramphenicol resulted in no changes in the antagonistic effect of acetic acid and salt. The addition of glutamate to phosphate buffer significantly increased the survival levels of <I>E. coli</I> O157:H7 after the acetic acid treatment; however, the survival levels were lower than those after the treatment with acetic acid alone. Thus, the addition of salt may increase the AR response of <I>E. coli</I> O157:H7; however, these survival mechanisms were not proven clearly. Therefore, further studies need to be performed to better understand the antagonism of acetic acid salt against <I>E. coli</I> O157:H7.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Salt addition increased acid resistance of <I>E. coli</I> O157:H7 against acetic acid. </LI> <LI> This antagonism was shown only in the presence of organic compounds. </LI> <LI> Salt addition may increase the acid resistance response of <I>E. coli</I> O157:H7. </LI> <LI> Acid resistance response could not fully explain the antagonism of acetic acid and salt. </LI> <LI> Decrease in a<SUB>w</SUB> may partially affect the antagonism of acetic acid and salt. </LI> </UL> </P>

Durable Press Finish of Cotton Fabric Using Malic Acid as a Crosslinker

Kim, Byung-Hak,Jang, Jinho,Ko, Sohk-Won The Korean Fiber Society 2000 Fibers and polymers Vol.1 No.2

It has been considered that malic acid, $\alpha$-hydroky succinic acid, could not form crosslinks in the cellulosic materials unless activated by other polycarboxylic acids such as butanetetracarboxylic acid or citric acid because there are only two carboxylic acids per molecule available fur the formation of one anhydride intermediate. However we found that the dicarboxylic malic acid with sodium hypophosphite catalyst without the addition of other crosslinkers was able to improve wrinkle resistance of cotton up to $294^{\circ}$(dry WRA) and $285^{\circ}$ (wet WRA), which is a measure of crosslinking level in cotton. $^1$H FT-NMR, FT-IR and GPC analysis indicated the in-situ formation of an trimeric $\alpha$, $\beta$-rnalic acid with a composition of 1:3 through the esterification between hydroxyl group and one of carboxylic groups in malic acid during curing. The crosslinking of cotton was attributed to the trimeric $\alpha$, $\beta$-malic acid, a tetracarboxylic acid, which can form two anhydride rings during curing. The influence of crosslinking conditions such as concentrations of malic acid and catalyst, pH of the formulation bath, and curing temperature were investigated in terms of imparted wrinkle resistance and whiteness. The addition of reactive polyurethane resin in the formulation slightly increased the mechanical strength retention of crosslinked fabric coupled with additional increase in wrinkle resistance.

사료첨가용 생균제 개발을 위한 마늘 내성 유산균의 배양 조건

김유진,장서정,박정민,김창욱,박영서 한국산업식품공학회 2010 산업 식품공학 Vol.14 No.1

파김치에서 분리한 마늘 내성 유산균인 Lactobacillus plantarum TJ-LP-002 균주의 균체생육과 항균활성에 영향을 미치는 배양조건 및 배지조건을 조사하였다. 선정 유산균의 배양 상등액 내에는 acetic acid, citric acid, lactic acid, tartaric acid와 같은 유기산이 존재하였고, 배양 중에 lactic acid와 acetic acid의 생성이 크게 증가하는 것으로 확인되었다. 단백질분해효소를 비롯한 각종 효소 처리에 의해 항균활성이 소실되지 않아, 선정 유산균이 생산하는 항균활성은 단백질성 물질이 아닌 산 생성에 의한 작용일 것으로 판단되었다. 항생제와 생균제의 병용 가능성을 확인하기 위하여 선정 유산균의 항생제 감수성을 조사한 결과, neomycin sulfate, spectinomycin dihydrochloride, lincomycin hydrochloride에 내성을 나타내었고, streptomycin sulfate에는 감수성을 나타내었으며, ampicillin trihydrate, chloramphenicol, erythromycin, tetracycline hydrochloride, kanamycin sulfate에는 중간 내성을 나타내었다. L. plantarum TJ-LP-002는 배양온도 30oC, 초기 pH 7.0, 24시간의 배양 조건에서 최적의 균체생육과 항균활성을 나타내었으며, 탄소원은 glucose 3%(w/v), 질소원은 yeast extract 3%(w/v) 첨가 시에 균체생육과 항균활성이 높게 나타났다. 무기염류는 manganese sulfate와 ammonium citrate가 항균활성에 많은 영향을 주는 것으로 나타났으며, 각 성분을 단독 첨가하는 것보다 혼합 첨가하는 것이 더 우수한 영향을 나타내는 것으로 확인되었다. Culture conditions of L. plantarum TJ-LP-002, the garlic resistant strain isolated from pakimchi (green onion kimchi), were investigated for the use of feed additives. Acetic acid, citric acid, lactic acid, and tartaric acid were detected in the culture supernatant, and especially the concentrations of lactic acid and acetic acid significantly increased during cultivation. The antimicrobial activity of L. plantarum TJ-LP-002 was not affected by proteases, calatase or cellulase, which showed that the antimicrobial activity might be due to the production of acids rather than proteinaceous antimicrobial substances. L. plantarum TJ-LP-002 was resistant to neomycin sulfate, spectinomycin dihydrochloride, and lincomycin hydrochloride, sensitive to streptomycin sulfate, and intermediate resistant to ampicillin trihydrate, chloramphenicol, erythromycin, tetracycline hydrochloride, and kanamycin sulfate. The optimum initial pH of medium, fermentation temperature and time for the cell growth and antibacterial activity were pH 7.0, 30oC and 24hr, respectively. The optimal composition of culture medium for the cell growth and antimicrobial activity was 3%(w/v) glucose as a carbon source, 3%(w/v) yeast extract as a nitrogen source, and manganese sulfate and ammonium citrate as inorganic salts. The combinatorial supplementation of these inorganic salts, rather than sole addition as an inorganic salt, resulted in better antibacterial activity.

ClC Chloride Channels in Gram-Negative Bacteria and Its Role in the Acid Resistance Systems

( Minjeong Kim ),( Nakjun Choi ),( Eunna Choi ),( Eun-jin Lee ) 한국미생물생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.7

Pathogenic bacteria that colonize the human intestinal tract have evolved strategies to overcome acidic conditions when they pass through the gastrointestinal tract. Amino acid-mediated acid resistance systems are effective survival strategies in a stomach that is full of amino acid substrate. The amino acid antiporter, amino acid decarboxylase, and ClC chloride antiporter are all engaged in these systems, and each one plays a role in protecting against or adapting to the acidic environment. The ClC chloride antiporter, a member of the ClC channel family, eliminates negatively charged intracellular chloride ions to avoid inner membrane hyperpolarization as an electrical shunt of the acid resistance system. In this review, we will discuss the structure and function of the prokaryotic ClC chloride antiporter of amino acid-mediated acid resistance system.

Quinolone 내성을 나타내는 Salmonella enterica subsp. enterica serovar Enteritidis의 유전학적 특성

김은기,오세아,김연선,이영기 대한구강악안면병리학회 2008 대한구강악안면병리학회지 Vol.32 No.3

In order to investigate the resistance patterns and molecular characteristics of resistance gene of 9 NA-resistant Salmonella enterica subsp. enterica serovar Enteritidis, Total of 101 isolates were isolated from stool sampes from 2005 to 2006. Among them, 48 isolates(47.5%) were identified S. Enteritidis, 24 isolates(23.8%) S. Typhi, 8 isolates(42.5%) S. Typhimurium, 7 isolates(6.9%) S. Paratyphi A and 14 isolates (13.9%) others Salmonellas. All of S. Enteritidis were resistant to ampicillin(43.8%), ticarcillin(43.8%), streptomycin(37.5%), chloramphenicol(29.2%), tetracycline(10.4%) and nalidixic acid(18.8%), respectively. All nalidixic acid-resistance isolates represented one point mutation in the quinolone resistance determining region(QRDR) of gyrA gene. Among them, 8(89%) isolates were substituted Tyr for Ser at position amino acid 83th or 1(11%) isolate was substituted Asn for Asp at position amino acid 87th. In consequence, Continued surveillance of NA-resistance among non-Typhi S. entetica isolates is needed to mitigate the increasing prevalence of nalidixic acid resistance.

복소임피던스법에 의한 인산형 연료전지용 전해질 매트릭스 특성

윤기현,장재혁,허재호,김창수,김태희 한국세라믹학회 1995 한국세라믹학회지 Vol.32 No.2

Materials retaining electrolyte of a phosphoric acid fuel cell (PAFC) have been prepared with SiC powder to SiC whisker mixing ratios of 1:1, 1:2, 1:3, 1:4, 0:1 by a tape casting method. When 3wt% dispersant (sorbitan monooleate) is added to a matrix, the porosity of the matrix decreases a little while the bubble pressure and area of the matrix increase remarkably in comparison with no dispersant content. Effect of the electrolyte resistance and the polarization resistance on perfomance of a PAFC has been investigated using A.C. impedance spectroscopy. With the increase of whisker content, the electrolyte resistance decreases due to the increase of porosity and acid absorbancy, and the polarization resistance increases due to the increase of surface roughness. The polarization resistance affects current density predominantly at the higher potential than 0.7V becuase the polarization resistance is considrably larger than the electrolyte resistance. Both the electrolyte resistance and the polarization resistance affect current density near 0.7V of the fuel cell operating potential because they have similar values. The electrolyte resistance affects current density predominantly at the lower potential than the fuel cell operating potential because the electrolyte resistance is larger than the polarization resistance.