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91.
Isolation of bacteria producing polyhydroxyalkanoates (PHA) from municipal sewage sludge 总被引:1,自引:0,他引:1
S. Vishnuvardhan Reddy M. Thirumala T. V. Kishore Reddy S. K. Mahmood 《World journal of microbiology & biotechnology》2008,24(12):2949-2955
Bacterial isolates from sludge samples collected at a local municipal sewage treatment plant were screened for bacteria producing
polyhydroxyalkanoates (PHA). Initially Sudan black B staining was performed to detect lipid cellular inclusions. Lipid-positive
isolates were then grown in a nitrogen limitation E2 medium containing 2% (w/v) glucose to promote accumulation of PHA before
the subsequent staining with Nile blue A. The positive isolates were quantified initially with a u.v. spectrophotometer, for
a very large number of isolates (105) and among them high PHA-producing isolates (15) were selected and were confirmed by
gas chromatographic analysis. The GC analysis showed the polymers produced by 13 of the selected isolates to be polyhydroxybutyrate
(PHB), and the remaining two isolates produced polyhydroxybutyrate-co-hydroxyvalerate (PHB-co-HV) copolymer. The proportion
of the PHA-positive bacterial isolates showed variability in the number of PHA accumulators during various months. The correlation
of PHB production with the cell dry weight (CDW) was found to be statistically significant. The metabolism of PHB in these
selected 15 isolates was studied using the Nile blue A staining, which showed an initial increase in the fluorescence followed
by a decline, on further incubation. All the selected 15 isolates were classified to genus level by studying their morphological
and biochemical characteristics. There were seven Bacillus species, three Pseudomonas species, two Alcaligenes species, two Aeromonas species, and one Chromobacterium species. 相似文献
92.
Lipid bilayers provide a natural anisotropic environment for membrane proteins and can serve as apolar reservoirs for lipid-derived second messengers or lipophilic drugs. Partitioning of lipophilic agents changes the lateral pressure distribution in the bilayer, affecting integral proteins. p-Hydroxybenzoic acid esters (parabens) are amphipathic compounds widely used as food and cosmetics preservatives, but the mechanisms of their broad antibacterial action are unknown. Here we describe effects of ethyl, propyl, and butyl parabens on the gating of the bacterial mechanosensitive channel of small conductance (MscS) and compare them with the surface activity and lateral pressure changes measured in lipid monolayers in the presence of these substances. Near the bilayer-monolayer equivalence pressure of 35 mN/m, ethyl, propyl, or butyl paraben present in the subphase at 1 mM increased the surface pressure of the monolayer by 5, 12.5, or 20%, respectively. No spontaneous activation of MscS channels was observed in patch-clamp experiments with parabens added from either the cytoplasmic or periplasmic side. Increasing concentrations of parabens on the cytoplasmic side of excised patches shifted activation curves of MscS toward higher tensions. A good correlation between the pressure increases in monolayers and shifts in activation midpoints in patch-clamp experiments suggested that the more hydrophobic parabens partition more strongly into the lipid and exert larger effects on channel gating through changes in lateral pressure. We show that cytoplasmically presented ethyl or butyl parabens both hasten the process of desensitization of MscS and influence inactivation differently. The higher rate of desensitization is likely due to increased lateral pressure in the cytoplasmic leaflet surrounding the gate. Neither of the parabens strongly affects the rate of recovery and does not seem to penetrate the TM2-TM3 interhelical clefts in MscS. We conclude that the bacterial mechanosensitive channel MscS provides a sensitive readout of lateral membrane pressure exerted by amphipathic molecules but may not be the primary target for the parabens in their antimicrobial activity. 相似文献
93.
Kishore M. Gadde Corette B. Parker Lauren G. Maner H. Ryan Wagner Eric J. Logue Marc K. Drezner K. Ranga R. Krishnan 《Obesity (Silver Spring, Md.)》2001,9(9):544-551
Objective: On the basis of the clinical observations that bupropion facilitated weight loss, we investigated the efficacy and tolerability of this drug in overweight and obese adult women. Research Methods and Procedures: A total of 50 overweight and obese (body mass index: 28.0 to 52.6 kg/m2) women were included. The core component of the study was a randomized, double‐blind, placebo‐controlled comparison for 8 weeks. Bupropion or placebo was started at 100 mg/d with gradual dose increase to a maximum of 200 mg twice daily. All subjects were prescribed a 1600 kcal/d balanced diet and compliance was monitored with food diaries. Responders continued the same treatment in a double‐blind manner for an additional 16 weeks to a total of 24 weeks. There was additional single‐blind follow‐up treatment for a total of 2 years. Results: Subjects receiving bupropion achieved greater mean weight loss (last‐observation‐carried‐forward analysis) over the first 8 weeks of the study (p = 0.0001): 4.9% ± 3.4% (n = 25) for bupropion treatment compared with 1.3% ± 2.4% (n = 25) for placebo treatment. For those who completed the 8 weeks, the comparison was 6.2% ± 3.1% (n = 18) vs. 1.6% ± 2.9% (n = 13), respectively(p = 0.0002), with 12 of 18 of the bupropion subjects (67%) losing over 5% of baseline body weight compared with 2 of 13 in the placebo group (15%; p = 0.0094). In the continuation phase, 14 bupropion responders who completed 24 weeks achieved weight loss of 12.9% ± 5.6% with fat accounting for 73.5% ± 3.7% of the weight lost and no change in bone mineral density as assessed by DXA. Bupropion was generally well‐tolerated in this sample. Discussion: Bupropion was more effective than placebo in achieving weight loss at 8 weeks in overweight and obese adult women in this preliminary study. Initial responders to bupropion benefited further in the continuation phase. 相似文献
94.
95.
Volatile fatty acid production during anaerobic mesophilic digestion of tea and vegetable market wastes 总被引:3,自引:0,他引:3
Lata Kusum Rajeshwari K.V. Pant D.C. Kishore V.V.N. 《World journal of microbiology & biotechnology》2002,18(6):589-592
Extraction of the organic content from vegetable market waste and tea waste was carried out in a packed digester for 24 and 300 h respectively. The sequence of appearance of volatile fatty acids during digestion of both the substrates was found to be different. The sequence was (Acetic, Propionic) > (Isobutyric, Butyric) > Valeric for digestion of vegetable market waste while it was Isovaleric > (Isobutyric, Acetic) > Propionic during digestion of tea waste. During the course of digestion, the early appearance of an acid did not relate to its high concentration. The rate of production of acetic acid and propionic acid was found to be higher than other volatile acids during digestion of both the substrates, although it was approximately ten times higher for vegetable market waste compared to tea waste. The acids can be arranged in four groups according to their rate of production as Acetic > Propionic > Butyric > (Valeric, Isobutyric) for vegetable market waste and Acetic > Isobutyric > Isovaleric > Propionic for tea waste. 相似文献
96.
97.
A highly specific inducible membrane-bound 4-pyridoxic acid dehydrogenase has been solubilized and purified to apparent homogeneity from Pseudomonas MA-1 grown with pyridoxine as a sole source of carbon and nitrogen. The undenatured enzyme migrates as a single band on gel electrophoresis; denatured preparations show two barely resolved bands (Mr = 63,000 and 61,000). Undenatured preparations aggregate readily, as evidenced by Mr values of 148,000, 470,000, and greater than 670,000 obtained by density gradient centrifugation or by gel filtration under various conditions. The enzyme contains FAD but no Fe or acid-labile S; an average minimum molecular weight of 131,000 was calculated from the FAD content. In the presence of 2,6-dichloroindophenol, the enzyme dehydrogenates 4-pyridoxic acid to the corresponding aldehyde; this reaction is not inhibited by CN-. At the pH optimum of 8.0, a Vm of approximately 7.0 mumol min-1 mg-1 and a Km of 9 microM were obtained. 2,6-Dichloroindophenol, phenazine methosulfate, and menadione are effective electron acceptors; ubiquinones are less active, while NAD, FAD, and O2 are inactive. However, in membrane fractions, oxygen supports 4-pyridoxic acid oxidation via a CN--sensitive electron transport chain, indicating that the dehydrogenase probably is coupled to ATP generation in such preparations. 相似文献
98.
Background
Intracellular trafficking of mycobacteria is comprehensively dependent on the unusual regulation of host proteins. Recently, we have reported that infection of macrophages by Mycobacterium tuberculosis H37Rv (Rv) selectively downregulates the expression of PKCα while infection by Mycobacterium smegmatis (MS) does not. 相似文献99.
Mark A. Seefeld Hong Lin Joerg Holenz Dave Downie Brian Donovan Tingting Fu Kishore Pasikanti Wei Zhen Matthew Cato Khuram W. Chaudhary Pat Brady Tania Bakshi Dwight Morrow Sridharan Rajagopal Swapan Kumar Samanta Naveena Madhyastha Bharathi Mohan Kuppusamy Robert W. Dougherty Yasuji Matsuoka 《Bioorganic & medicinal chemistry letters》2018,28(23-24):3793-3797
Neuronal voltage-gated potassium channels, KV7s, are the molecular mediators of the M current and regulate membrane excitability in the central and peripheral neuronal systems. Herein, we report novel small molecule KV7 openers that demonstrate anti-seizure activities in electroshock and pentylenetetrazol-induced seizure models without influencing Rotarod readouts in mice. The anti-seizure activity was determined to be proportional to the unbound concentration in the brain. KV7 channels are also expressed in the bladder smooth muscle (detrusor) and activation of these channels may cause localized undesired effects. Therefore, the impact of individual KV7 isoforms was investigated in human detrusor tissue using a panel of KV7 openers with distinct activity profiles among KV7 isoforms. KCNQ4 and KCNQ5 mRNA were highly expressed in detrusor tissue, yet a compound that has significantly reduced activity on homomeric KV7.4 did not reduce detrusor contraction. This may suggest that the homomeric KV7.4 channel plays a less significant role in bladder contraction and further investigation is needed. 相似文献
100.
Sheikh Farah Jin Yan Pasumarthi Kishore B.S. Kardami Elissavet Cattini Peter A. 《Molecular and cellular biochemistry》1997,176(1-2):89-97
Aspergillus fumigatus is a highly pathogenic fungus causing a wide spectrum of diseases in immunocompromised as well as immunocompetent hosts. The present work was undertaken to evaluate the cytotoxic nature of fractionated antigens of A. fumigatus against the mammalian cell lines (J774, RAW, CHO and L929). An enriched protein antigenic fraction of A. fumigatus was subjected to con A Sepharose and phenyl Sepharose chromatography. Antigenic fractions, ConAub (conA unbound) and PSC III (fraction III of phenyl Sepharose column) containing low mw antigens showed higher cytotoxicity as compared to other antigenic fractions. PSC III was further purified on HPLC resulting in an 18 kDa homogeneous protein. The purified protein showed high ELISA absorbance values for specific IgG and IgE antibodies in sera of ABPA patients. Monoclonal antibody raised against Asp fl, a major allergen/antigen of A. fumigatus recognised the purified 18 kDa by ELISA and western blot. The 18 kDa allergen/antigen or Asp fl showed similar toxicity towards all the four cell lines (macrophage and fibroblast) with an IC50 of 75 ng/ml or 4.16 nM. Reduction in toxicity of 18 kDa at low temperatures and potentiation in presence of ammonium chloride and monensin indicates mechanism of internalisation of 18 kDa in eukaryotic cells is similar to -sarcin. The present work shows that the 18 kDa allergen/antigen (Asp fl) is a major cytotoxin secreted by A. fumigatus which may play multiple roles in the pathogenesis of Aspergillosis through allergenicity, antigenicity and cytotoxicity. (Mol Cell Biochem 167: 89-97, 1997) 相似文献