The influence of scald water pH on the death rates of Salmonella typhimurium and other bacteria attached to chicken skin

Factory trials where scald tank water was maintained at pH 9.0± 0.2 showed that compared with the usual system of scalding when the water is at pH 6.0 for much of the working day the bacterial counts on carcases post scalding and plucking were significantly lower. In laboratory experiments, attached Salmonella typhimurium and the naturally occurring skin flora were found to be killed significantly more quickly in water at pH 9.0±0.2.     

The influence of scald water pH on the death rates of Salmonella typhimurium and other bacteria attached to chicken skin

Factory trials where scald tank water was maintained at pH 9.0 +/- 0.2 showed that compared with the usual system of scalding when the water is at pH 6.0 for much of the working day the bacterial counts on carcases post scalding and plucking were significantly lower. In laboratory experiments, attached Salmonella typhimurium and the naturally occurring skin flora were found to be killed significantly more quickly in water at pH 9.0 +/- 0.2.     

Salmonella and campylobacter contamination of broiler chicken carcasses and scald tank water: the influence of water pH

Scalding at 50°± 0.5°C, in water maintained at pH 9.0 ± 0.2 by the addition of sodium hydroxide, had no effect on the incidence of salmonella or campylobacter contamination of chicken carcasses. There were significant reductions, however, in the numbers of these organisms in the water itself.     

The Effects of pH and Levels of Organic Matter on the Death Rates of Salmonellas in Chicken Scald-tank Water

The immersion scalding of chicken carcases at 52°C for 2.5 min was found to result in the accumulation of bacteria and organic matter in the water. Disassociation of ammonium urate present in chicken faeces caused the pH value of the water to fall rapidly from 8.4 to 6.0. This pH was maintained for most of the time the tank was in operation. The change in pH value greatly increased the heat resistance of some common salmonella serotypes with a strain of Salmonella typhimurium being the most resistant, having a D52°C value of 34.5 min. The pH value of the water was found to be close to the optimum for the heat resistance of salmonellas. In scald water at pH 5.9–6.0 the death rate of Salm. typhimurium was shown to be independent of organic matter levels indicating that pH was the major influence on heat resistance.     

KCl potentiation of the virucidal effectiveness of free chlorine at pH 9.0.

In studies at 5 degrees C and pH 9.0, poliovirus 1 was inactivated about 15 times more rapidly by free chlorine (FC) in purified water in the presence of 1,262 mg of KCl per liter (approximately 0.0169 M) than in the absence of KCl. In the presence of 526 mg of KCl per liter, the virus was inactivated about seven times more rapidly by FC than in the absence of KCl. At a level of 21 mg/liter, KCl did not significantly potentiate the virucidal activity of FC in purified water. Although poliovirus 1 was inactivated almost three times more rapidly by FC in borate-buffered purified water than in purified water, the presence of the buffer did not alter the extent of potentiation by KCl. Most of FC exists as OCl- at pH 9.0. Tap water has been shown to markedly potentiate the polivirucidal effectiveness of FC at pH 9.0. For the same degree of virucidal potentiation of FC at this pH, a considerably greater quantity of KCl was required in purified water than the total salt content that appeared to be present in the tap water.     

贵州麻若平台泥炭藓沼泽中泥炭藓持水特性及其与土壤营养元素关系研究

泥炭藓属（Sphagnum）植物的持水特性在泥炭湿地形成过程中起着重要作用,研究其与土壤营养元素之间的关系有助于地区湿地保护和退化湿地的修复。以贵州麻若平台分布的泥炭沼泽为对象,采用方差分析、相关性分析和冗余分析等方法对沼泽内泥炭藓的生物量、蓄水量、吸水率和土壤营养元素含量等进行研究。结果显示,该区域泥炭藓物种组成主要包括狭叶泥炭藓（Sphagnum cuspidatum Ehrh.）、多纹泥炭藓（Sphagnum multifibrosum X.J.Li&M.Zang）和卵叶泥炭藓（Sphagnum ovatum Hampe.）3种,狭叶泥炭藓为优势种,占泥炭藓总盖度的87.2%。沼泽中泥炭藓的生物量为（0.62 ±0.01）kg/m²,自然蓄水量为（9.42 ±0.45）kg/m²,饱和吸水率达1827.41%±34.56%,说明泥炭藓具有很强的持水能力。RDA分析表明,泥炭藓的生物量、饱和吸水量和饱和吸水率主要受沼泽土壤总钾、总磷、有效磷、有效氮、有效钾的影响,泥炭藓的鲜重、自然蓄水量和自然吸水率受土壤pH和水位的影响较大。泥炭藓的生物量、饱和蓄水量、饱和吸水率与土壤总钾含量呈正相关,与土壤总磷、有效磷、总钾、有效氮、总氮、有机质含量呈负相关,说明土壤总磷、有效磷、有效钾、有效氮、总氮、有机质对沼泽中泥炭藓的持水能力具有抑制作用。     

Glial Alkalinization Detected In Vivo by 1H-15N Heteronuclear Multiple-Quantum Coherence-Transfer NMR in Severely Hyperammonemic Rat

Abstract: Brain [5-¹⁵N]glutamine amide protons were selectively observed in vivo by ¹H-¹⁵N heteronuclear multiple-quantum coherence-transfer NMR in spontaneously breathing, severely hyperammonemic rats during intravenous [¹⁵N]ammonium acetate infusion and the subsequent recovery period. The linewidth of brain [5-¹⁵N]-glutamine amide proton H_z increased from 36 ± 2 Hz at 3.4 h to 58 ± 6 Hz after 5.7 h of infusion, a net increase of 22 ± 6 Hz. Concomitantly, brain ammonia concentration increased from 1.7 to 3.5 ± 0.2 µmol/g and the rat progressed from grade III to grade IV encephalopathy. On recovery to grade III and decrease of brain ammonia concentration to 1.3 µmol/g, the linewidth returned to 37 ± 2 Hz. In aqueous solution, [5-¹⁵N]glutamine amide proton H_z underwent a 17-Hz linebroadening when pH was raised from 7.1 to 7.5 at 37°C, due to the increased rate of base-catalyzed exchange with water proton. Hence, linebroadening is a sensitive measure of changing intracellular pH. The 22-Hz linebroadening observed in vivo in severely hyperammonemic grade IV rats strongly suggests that the intracellular pH increases from 7.1 to about 7.4–7.5 in astrocytes where glutamine is synthesized and mainly stored. Probable mechanisms for the ammonia-induced alkalinization and decreased intraglial buffering capacity, as well as implications of the result for pathogenesis of hepatic encephalopathy, are discussed.     

ETHYL ALCOHOL REDUCTION OF SALMONELLA TYPHIMURIUM IN POULTRY FEED

This study was designed to evaluate the effect of ethyl alcohol as a potential treatment for reduction of Salmonella populations in poultry feed. Growth rate of S. typhimurium in tryptic soy broth was significantly reduced by addition of greater than 0.3% volume/volume of ethyl alcohol and growth was completely inhibited by addition of 5% ethyl alcohol. Ethyl alcohol concentrations of 20% volume/weight and greater significantly reduced initial S.typhimurium populations in poultry feed (for 20% treated, 2.31 ± 0.31 vs 3.39 ± 0.29 for untreated; P < 0.05). When feed treatment was administered either before or after inoculation of S. typhimurium with 60% ethyl alcohol or 0.04% buffered propionic acid, populations in feeds treated after inoculation were decreased to a nondetection level (< 1.0 log₁₀ CFU/g) by ethyl alcohol treatment but not by other treatments. Ethyl alcohol treatment may have the potential for reducing Salmonella spp. contamination in poultry feed.     

Mass cultivation of the nitrogen-fixing cyanobacteriumGloeotrichia natans,indigenous to rice-fields

Gloeotrichia natans, a nitrogen fixing cyanobacterium common in rice fields in the Philippines, was used for studies to establish key features of its physiology and potential production in outdoor cultures. Under optimal growth conditions (38 °C, pH 8.0, no carbon enrichment) the specific growth rate of rice-field isolate was 0.076 h^–1. The pH of the medium (between 6.5 and 9.0) did not influence the growth rate, but it did affect phycobiliprotein content, as reflected by a change in colour. At pH 7.0 the culture was green-brown, with phycobiliproteins constituting up to 10% of the total protein, while at pH 9.0 the culture was brownish-black and the pigment content was as high as 28% of the total protein. In outdoor cultures the specific growth rate was related directly to cell density in the range of 0.7–1.5 g dry weight 1^–1 at a rate of stirring of 30 rpm, and inversely related to cell density at half this rate. At a stirring of 30 rpm, daily production of outdoor cultures harvested to maintain cell densities of 0.7, 1.15 andw 1.5 g 1^–1 were 14.7, 17.1 and 18.1 g m^–2 d^t, respectively. This rate of production was maintained for more than 45 days. Phycobiliprotein content in the culture kept at a density of 1.5 g 1^–1 reached 14% of the total biomass.     

Salmonella and Campylobacter contamination of broiler chicken carcasses and scald tank water: the influence of water pH

Scalding at 50 degrees +/- 0.5 degrees C, in water maintained at pH 9.0 +/- 0.2 by the addition of sodium hydroxide, had no effect on the incidence of salmonella or campylobacter contamination of chicken carcasses. There were significant reductions, however, in the numbers of these organisms in the water itself.     

Purification and characterization of a tRNA methylase from Salmonella typhimurium.

A tRNA methylase, in which supK strains of Salmonella typhimurium are deficient, was purified from strain LT2 and characterized. Column chromatography of protein extracts from wild-type cells on phosphocellulose, diethylaminoethyl-Sephadex A-50, and hydroxlapatite resulted in an enzyme that was estimated to be about 50% pure. tRNA from S. typhimurium which had been incubated at pH 9.0 served as a substrate for this methylase. The enzyme has a molecular weight of about 50,000 as estimated by gel chromatography and by electrophoresis on sodium dodecyl sulfate-polyacrylamide gels. The optimal assay conditions, as well as the kinetics and stability of the enzyme, were studied. As with other tRNA-methylating enzymes, S-adenosylhomocysteine is a potent inhibitor.     

Gypsy moth parasitoids in the declining outbreak in Lithuania

A 3 year study was conducted on the parasitoids of gypsy moth larvae in two reducing outbreak areas in Lithuania. Overall parasitism of 25.0 ± 2.0% in the first post-culmination year was significantly lower than the 36.3 ± 1.4 and 35.2 ± 1.4% parasitism in the two subsequent years. When analysed in terms of the life stage at which the host was collected, the total parasitism over 3 years was constantly increasing from 3.1 ± 0.8 in the first to 72.5 ± 2.9% in the sixth instar. Parasetigena silvestris R.-D. dominated causing 48.7 ± 1.5% parasitism and 16.7 ± 0.6% larval mortality preferably in late instars. Phobocampe disparis Vier. contributed to 21.9 ± 1.2% parasitism and 7.5 ± 0.5% mortality recovering from early instar larvae. Meteorus pulchricornis Wes. parasitized 4.3 ± 0.6% gypsy moth larvae causing 1.5 ± 0.2% mortality and a few Apanteles species provided 2.8 ± 0.6% parasitism and 1.0 ± 0.2% mortality. The gypsy moth in Lithuania was reported to act as host for Rogas sp. (Hym., Braconidae) and Siphona boreata Mes. (Dipt., Tachinidae).     

SURVIVAL OF AN UNIRRADIATED SALMONELLA TYPHIMURIUM MARKER STRAIN INOCULATED IN POULTRY FEEDS AFTER IRRADIATION

The present study was designed to compare unirradiated Salmonella typhimurium survival during storage after inoculation in either irradiated or unirradiated poultry feed. The effects of irradiation (5 kGy) on the indigenous feed microflora and on the survival of marker strain of S. typhimurium contaminated after irradiation treatment were determined during 56 days of storage of either soybean meal (SBM) or meat and bone meal (MBM) based feeds. The initial aerobic bacterial populations were reduced more than 90% in both SBM (4.96 to 4.08 ± 0.03 log₁₀ CPU/g feed) and MBM (5.12 to 3.90 ± 0.03) by irradiation. Irradiation treatment reduced the average fungal counts during 56 days of storage in both SBM (4.24 to 2.74 ± 0.03) and MBM (4.38 to 2.15 ± 0.03) containing feeds. However, unirradiated S. typhimurium populations inoculated after irradiation of the feed were not different in either irradiated or nonirradiated SBM and MBM based feeds. Therefore, the differences in fungal versus bacterial sensitivity among the feed types and storage times suggests that gamma irradiation can alter the makeup of indigenous microbial populations in feed but this does not appear to have a discernible influence on subsequent survival of unirradiated S. typhimurium added as a dry inoculum after irradiation.     

Effect of rat polymorphonuclear leukocyte granule components on the growth and survival of Pseudomonas aeruginosa and Salmonella typhimurium

Granule contents from rat polymorphonuclear neutrophils were prepared by extraction with 0.2 M acetate buffer (pH 4.0), dialyzed against phosphate-buffered saline (pH 7.0), and tested for bactericidal activity against selected target bacteria. Salmonella typhimurium LT-2 and a series of progressively rough lipopolysaccharide outer membrane mutants derived from it were used to monitor antimicrobial activity. Although an antimicrobial potential was present in rat granule contents for S. typhimurium, the growth of Pseudomonas aeruginosa PAO-1 in antimicrobial assay mixtures containing rat granule contents was substantially enhanced over control values. The growth enhancement property of the granule protein was heat resistant and promoted increased oxygen consumption by whole cells.     

Re-evaluation of the kinetics of lactate dehydrogenase-catalyzed chain oxidation of nicotinamide adenine dinucleotide by superoxide radicals in the presence of ethylenediaminetetraacetate.

The chain oxidation of lactate dehydrogenase-bound NADH initiated by superoxide radicals and propagated by oxygen was studied with pulse radiolysis. The kinetic parameters were re-evaluated in a system with carefully purified reagents (water and other chemicals) and in the presence of EDTA. The rate constant for the oxidation of the enzyme-bound NADH by O2- is calculated from the observed pseudo-first order disappearance of NADH and the chain length (molecules of NADH oxidized per O2- anion generated in the pulse). It is (1.0 +/- 0.2) X 10(5) M-1 S-1, consistent within a 13-fold variation in lactate dehydrogenase. NADH complex concentration and with varying chain length up to 6.1. Based on experiments with varying pH values from 4.5 to 9.0, the rate constant for oxidation of enzyme-bound NADH by HO2 is estimated to be 2.0 X 10(6) M-1 S-1.     

Relationship between cavitation and water uptake in rose stems

Cavitation in rose stems ( Rosa hybrida L.) was assessed in both intact plants and excised flowers, by measurement of ultrasonic acoustic emissions at the stem surface and determination of the air-conductivity of 2.5-cm segments that were attached at one end to air at low pressure (0.01 MPa). On sunny days the stems of intact rose plants showed acoustic emissions and conductivity to air, starting early in the morning. In Cara Mia and Sonia rose plants the cavitations were repaired during the late afternoon; in Madelon plants this repair only occurred overnight. Water flow was seriously impaired in stems of Cara Mia roses cut around midday, on sunny days.
During dehydration of cut roses in air the onset of a high rate of acoustic emissions coincided with a low rate of water uptake when stems were subsequently placed in water. High emission frequency occurred after 2.4 ± 0.7 h, 6.8 ± 4.3 h and 19.8 ± 9.0 h of exposure to air in Cara Mia, Madelon and Sonia roses, respectively. A low rate of water uptake in excised stems placed in water was found after 3–4, 9–12 and 24–36 h of desiccation in air, respectively. The onset of the high emission frequency corresponded with a water potential of −1.7, −2.9 and −3.8 MPa in the three cultivars, respectively.
It is concluded that a high number of cavitations may occur in noncut stems of rose plants, leading to low water uptake immediately after excision, depending on the weather and the cultivar, and that the low rate of water uptake after a period of dry storage, among the three rose cultivars investigated, is correlated with the presence of a high number of cavitated xylem elements.     

龙须菜海藻场构建及其对水环境因子的影响

2010年2月～2010年5月,在汕头南澳岛海域,通过设计不同的主绳间距和苗绳间距研究了龙须菜(Gracilaria lemaneifomis)海藻场的构建模式及其对养殖附近海域环境的影响。结果表明,在不同的筏式养殖密度中,主绳间距在0.3～0.4m,苗绳间距在0.1～0.2m之间,龙须菜的生长速率较高。龙须菜海藻场构建后,养殖海域的无机氮(IN)平均值为133.40±15.18μg·L^-1,对照海域的无机氮平均值为153.81±11.97μg·L^-1,养殖海域显著低于对照海域(p<0.05);养殖海域的无机磷(IP)平均值为13.16±1.38μg·L^-1,对照海域的平均值为15.55±1.05μg·L^-1,养殖海域的显著低于对照海域的(p<0.05)。养殖海域叶绿素(Chl-a)的平均值为1.86±0.23mg·m^-3,对照海域的平均值为2.44±0.30mg·m^-3,养殖海域显著低于对照海域(p<0.05);养殖海域的透明度平均值为1.76±0.09m,对照海域的透明度为1.41±0.15m,养殖海域显著高于对照海域(p<0.05):养殖海域的溶解氧(DO)平均值为9.55±0.46mg·L^-1,对照海域的平均值为8.90±0.37mg·L^-1,养殖海域显著高于对照海域(p<0.05)。研究表明,构建龙须菜海藻场可以显著增加海水中DO浓度,抑制微藻生长繁殖,吸收水体营养盐,改善水质质量。     

Expression of the Na+/H+ antiporter gene (g1-nhaC) of alkaliphilic Bacillus sp. G1 in Escherichia coli

A Na(+)/H(+) antiporter gene was isolated from alkaliphilic Bacillus sp. G1. The full-length sequence of the Na(+)/H(+) antiporter gene was obtained using a genome walking method, and designated as g1-nhaC. An ORF preceded by a promoter-like sequence and a Shine-Dalgarno sequence, and followed by a terminator-like sequence was identified. The deduced amino acid sequence consists of 535 amino acids, and a calculated molecular mass of 57 776 Da. g1-nhaC was subsequently cloned into pET22b(+) and expressed in Escherichia coli BL21 (DE3). Recombinant E. coli harboring the g1-nhaC gene was able to grow in modified L medium at various concentrations of NaCl (0.2-2.0 M) at different pH values. The recombinant bacteria grew well in the medium with concentrations of NaCl as high as 1.75 M at pH 8.0-9.0. Minimal growth was observed at 2.0 M NaCl, pH 8.0-9.0. At pH 10, the recombinant bacteria grew well in a medium with a low concentration of NaCl (0.2 M). These results suggested that the g1-NhaC antiporter from Bacillus sp. G1 plays a role in Na(+) extrusion at lower pH values and in pH homeostasis at pH 10 under Na(+)-limiting conditions.     

The effect of alkaline earth cations and of ionic strength on the dissociation of earthworm hemoglobin at alkaline pH

1. The effect of alkaline earth cations on the dissociation of the extracellular hemoglobin of Lumbricus terrestris and the effect of ionic strength on the dissociation of the hemoglobins of L. terrestris and Tubifex tubifex at concentrations of ca 2.5 mg/ml, over the pH range 9.0-10.5 was investigated using ultracentrifugation to separate the dissociated from the undissociated molecules. 2. Mg(II), Ca(II) and Sr(II) at concentrations of up to 0.2 M, decreased the dissociation of Lumbricus oxyhemoglobin from 70% at pH 9.0 and 100% at pH 9.5 and higher, to 20-30% at 0.05 M. The three cations were equally effective in decreasing the extent of dissociation of L. terrestris oxyhemoglobin over the pH range 9.0-10.5, with a K1/2 of ca 10 mM. 3. The dissociation of L. terrestris oxyhemoglobin over the pH range 9.0-10.5 was decreased only to 50-60% in the presence of up to 0.5 M NaCl or KCl; there was no further decrease in dissociation at concentrations of the two salts up to 1.5 M. 4. The dissociation of T. tubifex oxyhemoglobin over the pH range 9.0-10.0 was decreased from 100% to ca 40-50% in the presence of 0.5 M NaCl or KCl with little or no change at higher concentrations. At pH 10.5 and 11.0 the decrease in dissociation was more gradual, reaching ca 50% at 1.5 M NaCl.     

Bovine serum albumin partitioning in an aqueous two-phase system: Effect of pH and sodium chloride concentration

The partitioning of bovine serum albumin (BSA) in a polyethylene glycol 3350 (8% w/w)–dextran 37 500 (6% w/w)–0.05 M phosphate aqueous two-phase was investigated at different pHs, at varying concentrations of sodium chloride at 20°C. The effect of NaCl concentration on the partition coefficient of BSA was studied for the PEG–dx systems with initial pH values of 4.2, 5.0, 7.0, 9.0, and 9.8. The NaCl concentrations in the phase systems with constant pH value were 0.06, 0.1, 0.2, 0.3, and 0.34 M. It was observed that the BSA partition coefficient decreased at concentrations smaller than 0.2 M NaCl and increased at concentrations greater than 0.2 M NaCl for all systems with initial pHs of 4.2, 5.0, 7.0, 9.0, and 9.8. It was also seen that the partition coefficient of BSA decreased as the pH of the aqueous two-phase systems increased at any NaCl salt concentration studied.