• Title/Summary/Keyword: low pH tolerance

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Characterization of Lactobacillus reuteri BCLR-42 and Lactobacillus plantarum BCLP-51 as novel dog probiotics with innate immune enhancing properties

  • Kim, Eun Jin;Kang, Yeong Im;Bang, Tae Il;Lee, Myoung Han;Lee, Sang Won;Choi, In Soo;Song, Chang Seon;Lee, Joong Bok;Park, Seung Yong
    • Korean Journal of Veterinary Research
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    • v.56 no.2
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    • pp.75-84
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    • 2016
  • Probiotics that are able to provide beneficial effects on animal health have become important ingredients of dog foods. This study was conducted to characterize the probiotic potentials of two strains, Lactobacillus reuteri BCLR-42 and Lactobacillus plantarum BCLP-51, that were derived from feces of healthy dogs and evaluated based on tolerance to low pH and bile acid, antimicrobial activities, enzyme profiles, sensitivity to antibiotics, and innate immune enhancing potentials. Both strains showed survival of more than 90% at pH 3 and 0.2% bile acid and exhibited broad antimicrobial activities against indicator bacteria. Moreover, both strains showed high sensitivity to antibiotics, except vancomycin, metronidazole, and gentamicin. The alkaline phosphatase was negligible (score 0), whereas they showed strong beta galactosidase activity (score range 5 or 3, respectively). The phagocytosis and oxidative burst activities of canine granulocytes were significantly enhanced in response to both strains. These results show that both strains have the capability to act as probiotics and the potential for application as ingredients in dog foods.

Isolation and Characterization of Potential Starter Yeasts from Traditional Moroccan Sourdoughs

  • Aouine, Mouna;Misbah, Asmae;Elabed, Soumya;Haggoud, Abdelatif;Mohammed, Iraqui Houssaini;Koraichi, Saad Ibnsouda
    • Microbiology and Biotechnology Letters
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    • v.49 no.4
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    • pp.501-509
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    • 2021
  • The increasing demand for baked products has given a boost to research on isolation and selection of novel yeast strains with improved leavening activity. Twelve sourdough samples were collected from several localities of the Fez region in Morocco. The pH and total titratable acidity (TTA) values of these samples varied from 3.03-4.63 and 14-17.5 ml of 0.1 N NaOH/10 g of sourdough, respectively, while yeast counts ranged from 5.3 6.77 Log CFU/g. Thirty-two yeast isolates were obtained and evaluated for their leavening ability. Out of all isolates, four yeasts molecularly identified as Saccharomyces cerevisiae (three strains) and Kluyveromyces marxianus (one strain) showed highest specific volumes of 4.69, 4.55, 4.35 and 4.1 cm3/g, respectively. These strains were further assessed for their tolerance to high concentrations of salt, sugar, elevated temperatures, and low pH conditions. K. marxianus showed higher resistance than the S. cerevisiae. Thus, Moroccan sourdoughs harbor technologically relevant yeasts that could be used as potential starters for bread preparation.

Crystal Structure of the Regulatory Domain of AphB from Vibrio vulnificus, a Virulence Gene Regulator

  • Park, Nohra;Song, Saemee;Choi, Garam;Jang, Kyung Ku;Jo, Inseong;Choi, Sang Ho;Ha, Nam-Chul
    • Molecules and Cells
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    • v.40 no.4
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    • pp.299-306
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    • 2017
  • The transcriptional activator AphB has been implicated in acid resistance and pathogenesis in the food borne pathogens Vibrio vulnificus and Vibrio cholerae. To date, the full-length AphB crystal structure of V. cholerae has been determined and characterized by a tetrameric assembly of AphB consisting of a DNA binding domain and a regulatory domain (RD). Although acidic pH and low oxygen tension might be involved in the activation of AphB, it remains unknown which ligand or stimulus activates AphB at the molecular level. In this study, we determine the crystal structure of the AphB RD from V. vulnificus under aerobic conditions without modification at the conserved cysteine residue of the RD, even in the presence of the oxidizing agent cumene hydroperoxide. A cysteine to serine amino acid residue mutant RD protein further confirmed that the cysteine residue is not involved in sensing oxidative stress in vitro. Interestingly, an unidentified small molecule was observed in the inter-subdomain cavity in the RD when the crystal was incubated with cumene hydroperoxide molecules, suggesting a new ligand-binding site. In addition, we confirmed the role of AphB in acid tolerance by observing an aphB-dependent increase in cadC transcript level when V. vulnificus was exposed to acidic pH. Our study contributes to the understanding of the AphB molecular mechanism in the process of recognizing the host environment.

A Study on Freezing Possibility of Jeung-Pyun Batter (증편 반죽의 냉동 가능성에 관한 연구)

  • 최원석;노정옥;우경자
    • Journal of the East Asian Society of Dietary Life
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    • v.13 no.6
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    • pp.593-600
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    • 2003
  • This study was carried out in order to investigate the possibility of frozen rice batter for the manufacturing of Jeung-pyun. Despite of its unique taste and texture, Jeung-pyun is not consumed much because it needs long time to make. The physicochemical, sensory, rheological and surface characteristics of Jeung-pyun were analyzed to develop the easy manufacture method. The storage condition of rice batter was used at -2$0^{\circ}C$ up to 4 weeks. Statistical data analysis was completed using a SAS program. The results are summarized as follow: The pH brix% and sugar content of all samples which added low-temperature tolerance raw yeast or regular raw yeast decreased during the fermentation. Kind of yeast did not influence on the moisture content of the Jeung-pyun batter. Specific volume and carbon dioxide evolution of Jeung-pyun batter were highest when the rice batter was frozen for 1 week regardless of the kind of yeast. Overall quality of frozen batter of Jeung-pyim at -2$0^{\circ}C$ for 4 weeks had the highest score among different samples. As the test results of mechanical characteristics, cohesiveness, gumminess, brittleness, hardness and springiness did not show any significant differences statistically. The result clearly suggests that freezing the rice batter is a possibile way to manufacture Jeung-pyun.

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Ginseng Cultural Management and Research Update in Atlantic Canada

  • Ju, H.Y.;Asiedu, S.K.;Hong, S.C.;Gray, B.;Sampson, G.;LeBlanc, P.
    • Proceedings of the Ginseng society Conference
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    • 1998.06a
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    • pp.103-108
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    • 1998
  • The Canadian production of American ginseng (Panax quinquefolius L.) occurs mainly in Ontario, British Columbia and the Atlantic provinces. Although ginseng is a profitable crop, its successful production is dependent on careful consideration of cultural management f include site selection, site preparation, seed selection and handling, shading actors which and mulching, pest and nutritional management, and handling of harvested crops. Diseases of particular concern in Atlantic Canada are root rots caused by Phytopkthora cactorum, Cylindrocarpon destructans and Fusarium sp. Recently two systemic fungicides (metalaxyl and fosetylal) were registered; however, growers in Atlantic Canada have experienced metalaxyl resistance resulting from the reliance on this single compound for the control of Phytophthora sap. Current research being conducted on alternative control of these diseases will be discussed. In weed control research, 2, 4-D, MCPA, clopyralid have continued to show promise for weed contro1 at low rates. In trials to evaluate non-selective herbicides as post-senescence or pre-emergence in ginseng, glyphosate (Round-up) provided control of perennials as well as willowherb and lambsquarters. In phytoxicity trials, ginseng significantly tolerated grass herbicides, including clethodim, rimsulfuron, trakloxydim, nicosulfuron and fenoxyprop. For broadleaf herbicides, significant tolerance was shown for bromoxynil, thifensulfuron methyl, flumetulam/clopyralid, thifensulfuro/tribenuron. Disease and weed management of ginseng in Atlantic Canada will be discussed.

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Evaluation of Field Application of Soil Conditioner and Planting Chrysanthemum zawadskii on the Roadside Soils Damaged by Deicing Agents

  • Yang, Ji;Lee, Jae-Man;Yoon, Yong-Han;Ju, Jin-Hee
    • Journal of People, Plants, and Environment
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    • v.23 no.6
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    • pp.625-636
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    • 2020
  • Background and objects: Soil contamination caused by CaCl2 that is used to deice slippery roads in winter is now recognized as one of the major causes of damage of roadside plants. The aim of this study is to identify the salt mitigation effects of planting Chrysanthemum zawadskii and using a soil conditioner. Methods: The study was conducted at the site where Pinus densiflora f. multicaulis was planted on the roadside between Konkuk University Sageori and Danwol Samgeori located in Chungju-si. We classified the soils collected from the field experimental site according to the degree of the damage caused by deicing agents and divided the site into six blocks of three 80 × 80 cm plots replicated by treatment type. Three selected plots were treated with loess-balls on the soil surface (high salinity with loess-balls, medium salinity with loess-balls, low salinity with loess-balls) and three were left as an untreated control (H = high salinity, M = medium salinity, L = low salinity). The soil properties were measured including pH, EC and exchangeable cations as well as the growth of Chrysanthemum zawadskiia. Results: In the results of soil analysis, pH before planting Chrysanthemum zawadskiia was 6.39-6.74 and in September, five months after planting, the acidity was reduced to 5.43-5.89. Electrical conductivity (EC) was measured to be H > M > L with the higher degree of damage by deicing agents. The analysis of deicing exchangeable cations showed that the content of Ca2+ of soils were significantly correlated to deicing exchangeable cations (Ca2+, Na+, Mg2+) in the shoot part of Chrysanthemum zawadskii. The loess-ball treatment showed a lower content of deicing exchangeable cations than the treatment where Chrysanthemum zawadskiia was planted. Conclusion: In this study, the use of a new system made of loess-balls is proposed as a soil conditioner to protect soils from the adverse effects of road deicing salts. These data suggest that treatment of soil conditioners and planting Chrysanthemum zawadskiia are effective in mitigation of salt stress on the soils damaged by deicing agents.

Biosorption of Pb and Cd by Indigenous Bacteria Isolated from Soil Contaminated with Oil and Heavy Metals (유류와 중금속으로 오염된 토양에서 분리한 미생물의 Pb와 Cd 생물흡착 특성)

  • Kim, Sang-Ho;Chon, Hyo-Taek;Lee, Jong-Un
    • Economic and Environmental Geology
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    • v.42 no.5
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    • pp.427-434
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    • 2009
  • Indigenous bacterium which shows a tolerance to high metal toxicity was isolated from soil concomitantly contaminated with oil and heavy metals. The characteristics of the bacterium for Pb and Cd biosorption was investigated under the various experimental conditions such as bacterial growth phase, the initial metal concentration, the input biomass amount, temperature and pH. The Langmuir adsorption isotherm modeling was described to know the capacity and intensity of biosorption. The low initial concentration of heavy metals and high biomass has a maximum heavy metal removal efficiency, but biosorption capacity of Pb and Cd has different values. Biosorption efficiency was highest in the end of the microbial growth stage and under pH 5~9 condition, but was less affected by temperature variation of 25~$35^{\circ}C$. The maximum biosorption capacity for Pb and Cd was 62.11 and 192.31 mg/g, respectively and each $R^2$ was calculated as 0.71 and 0.98 by applying Langmuir isothermal adsorption equation. Biosorption for Cd was considered as monomolecular adsorption to single layer on the surface of cells, whereas biosorption for Pb was considered as accumulation process into the cell by the microbial metabolism and precipitation reaction with anion of bacteria.

Progress in Novel Oxides for Gate Dielectrics and Surface Passivation of GaN/AlGaN Heterostructure Field Effect Transistors

  • Abernathy, C.R.;Gila, B.P.;Onstine, A.H.;Pearton, S.J.;Kim, Ji-Hyun;Luo, B.;Mehandru, R.;Ren, F.;Gillespie, J.K.;Fitch, R.C.;Seweel, J.;Dettmer, R.;Via, G.D.;Crespo, A.;Jenkins, T.J.;Irokawa, Y.
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.3 no.1
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    • pp.13-20
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    • 2003
  • Both MgO and $Sc_2O_3$ are shown to provide low interface state densities (in the $10^{11}{\;}eV^{-1}{\;}cm{\;}^{-2}$ range)on n-and p-GaN, making them useful for gate dielectrics for metal-oxide semiconductor(MOS) devices and also as surface passivation layers to mitigate current collapse in GaN/AlGaN high electron mobility transistors(HEMTs).Clear evidence of inversion has been demonstrated in gate-controlled MOS p-GaN diodes using both types of oxide. Charge pumping measurements on diodes undergoing a high temperature implant activation anneal show a total surface state density of $~3{\;}{\times}{\;}10^{12}{\;}cm^{-2}$. On HEMT structures, both oxides provide effective passivation of surface states and these devices show improved output power. The MgO/GaN structures are also found to be quite radiation-resistant, making them attractive for satellite and terrestrial communication systems requiring a high tolerance to high energy(40MeV) protons.

Characteristics of isolated lactic acid bacteria and their effects on the silage quality

  • Wang, Siran;Yuan, Xianjun;Dong, Zhihao;Li, Junfeng;Guo, Gang;Bai, Yunfeng;Zhang, Junyu;Shao, Tao
    • Asian-Australasian Journal of Animal Sciences
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    • v.30 no.6
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    • pp.819-827
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    • 2017
  • Objective: Four lactic acid bacteria (LAB) strains isolated from common vetch, tall fescue and perennial ryegrass on the Tibetan Plateau were characterized, and their effects on the fermentation quality of Italian ryegrass (Lolium multiflorum Lam.) silage were studied. Methods: The four isolated strains and one commercial inoculant (G, Lactobacillus plantarum MTD-1) were evaluated using the acid production ability test, morphological observation, Gram staining, physiological, biochemical and acid tolerance tests. The five LAB strains were added to Italian ryegrass for ensiling at three different temperatures ($10^{\circ}C$, $15^{\circ}C$, and $25^{\circ}C$). Results: All isolated strains (LCG3, LTG7, I5, and LI3) could grow at $5^{\circ}C$ to $20^{\circ}C$, pH 3.0 to 8.0 and NaCl (3.0%, 6.5%). Strains LCG3, LTG7, I5, and LI3 were identified as Lactobacillus plantarum, Pediococcus acidilactici, Lactobacillus paraplantarum, and Lactobacillus casei by sequencing 16S rDNA, respectively. All LAB inoculants significantly (p<0.05) increased lactic acid (LA) contents and ratios of lactic acid to acetic acid, and reduced pH and ammonia nitrogen/total nitrogen (AN/TN) compared with uninoculated silages at various temperatures ($10^{\circ}C$, $15^{\circ}C$, and $25^{\circ}C$). Compared to the commercial inoculant G, I5, and LI3 showed similar effects on improving the silage quality of Italian ryegrass at $10^{\circ}C$ and $15^{\circ}C$, indicated by similar pH, LA content and AN/TN. Conclusion: All inoculants could improve the silage fermentation quality at various temperatures ($10^{\circ}C$, $15^{\circ}C$, and $25^{\circ}C$). At the temperature of $10^{\circ}C$ and $15^{\circ}C$, strain I5 and LI3 had similar effects with the commercial inoculant G on improving the silage quality of Italian ryegrass.

Production, Nutritional Quality and In vitro Methane Production from Andropogon gayanus Grass Harvested at Different Maturities and Preserved as Hay or Silage

  • Ribeiro, G.O. Jr.;Teixeira, A.M.;Velasco, F.O.;Faria, W.G. Junior;Pereira, L.G.R.;Chaves, A.V.;Goncalves, L.C.;McAllister, T.A.
    • Asian-Australasian Journal of Animal Sciences
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    • v.27 no.3
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    • pp.330-341
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    • 2014
  • Andropogon gayanus is an important grass due to its high biomass production, drought tolerance and favorable growth on low fertility acidic soils. Currently, there is little research on the impact of growth stage on the nutritional quality or the degree of $CH_4$ production that may arise from this forage during ruminal fermentation. The objectives of this study were to determine the effects of regrowth stage of A. gayanus on its chemical composition, in vitro production of gas and CH4, as well as in vitro dry matter (DM) digestibility when grown under tropical Brazilian conditions and conserved as hay or as silage. The nutritional value of A. gayanus grass declined with increasing maturity; however digestible DM yield linearly increased. After 112 d of regrowth, A. gayanus produced higher quality silage (higher lactate and lower pH and butyrate content) and higher DM yield. However, the low levels of crude protein at this time would make protein supplementation a necessity for proper rumen fermentation. No differences in $CH_4$ kinetic parameters were found with advancing maturity or preservation method (hay or silage).