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51.
Lactate dehydrogenase (LDH, EC 1.1.1.27) catalyses the reduction of pyruvate to lactate in facultative anaerobes. Whole cells of Lactobacillus plantarum NCIM 2084 showed low levels of LDH activity but permeabilization of cells by treatment with organic solvents toluene, chloroform and diethyl ether increased the measurable LDH activities, ether treated cells showing the highest increase. The maximum intracellular activity was obtained upon treating the cells with ether (1%) at 28°C for 1 min. The LDH activity in permeabilized cells was nearly three-fold higher than that in the cell-free extract prepared by sonication. The kinetic properties of LDH in the permeabilized cells were comparable to that of cell-free extract, indicating that catalytically it functions similar to the isolated enzyme. 相似文献
52.
S Hari Krishna S G Prapulla N G Karanth 《Journal of industrial microbiology & biotechnology》2000,25(3):147-154
Isoamyl butyrate, an important fruity flavor ester, was synthesized using Rhizomucor miehei lipase immobilized on a weak anion exchange resin (Lipozyme IM-20) by the esterification of isoamyl alcohol and butyric acid.
The effects of various reaction parameters such as substrate and enzyme concentrations, substrate molar ratio, temperature
and incubation time have been investigated. Yields above 90% were obtained with substrate concentrations as high as 2.0 M.
No evidence of enzyme inhibition by butyric acid was present up to 1.0 M concentration. Acid inhibition and, to a small extent,
alcohol inhibition were evident above 1.0 M substrate concentration. Conversions reached a saturation value by the end of
24–48 h of incubation due to the accumulation of the water of reaction. The equilibrium was successfully pushed forward towards
esterification by removing the accumulated water using a molecular sieve.Journal of Industrial Microbiology & Biotechnology (2000) 25, 147–154.
Received 09 February 2000/ Accepted in revised form 24 June 2000 相似文献
53.
SYNOPSIS. An ultrastructural investigation has been carried out on 180°-rotated ciliary meridians (inverted meridians) in Tetrahymena pyriformis temperature-sensitive mutant (molb/molb), syngen 1, strain B. The longitudinal, transverse and postciliary microtubular bands, the kinetodesmal fiber, and the parasomal sac, are shown to be disposed at a 180° angle to their normal positions or orientations. Other abnormalities are as folows: the first 2 basal bodies of the inverted meridian fail to organize into “couplets” and the inverted meridian intrudes into the anterior pole region; an extra longitudinal microtubular band is found in one of the cell lines. 相似文献
54.
目的:探讨Anisomycin诱导EAC细胞凋亡的机制。方法:利用MTT法观察Anisomycin对EAC细胞增殖的影响;应用An.nexinV—FITC和PI双染色检测Anisomycin作用下EAC细胞凋亡的变化;琼脂糖凝胶电泳检测Anisomycin作用下EAC细胞的DNA断裂片断;采用RT—PCR检测Anisomycin作用下Caspase-3mRNA的转录水平;WesternBlot分析Anisomycin处理的EAC细胞内Caspase-3蛋白的表达。结果:Anisomycin对EAC细胞增殖的抑制率随浓度的升高而增高,EAC细胞的凋亡水平也上升,随着Anisomycin浓度升高EAC细胞DNA断裂的寡核苷酸片段亦越趋明显,Caspase-3的mRNA和蛋白水平也上调,并明显高于阿霉素组。结论:结果表明,Anisomycin能够抑制EAC细胞的增殖,在体外可能通过激活Caspase-3凋亡信号而诱导EAC细胞的凋亡。 相似文献
55.
Transmission of plant viruses by aphid vectors 总被引:10,自引:0,他引:10
56.
Morphological forms and viability of Campylobacter species studied by electron microscopy. 总被引:13,自引:0,他引:13 下载免费PDF全文
Electron microscopic studies of Campylobacter revealed that different morphological forms predominate at different parts of a colony. At the periphery, cells were almost all spirals, while in the center of the colony cells were mainly coccus shaped. Unusual ring-shaped cells, "donuts", were observed in the raised, peripheral region of the colony. Donut or ring forms have not previously been reported for Campylobacter organisms. Our data indicate that young or actively growing cells are mainly spiral shaped. Older cells undergo a degenerative change to coccoid forms. The donut shape appears to be an intermediate stage between spirals and cocci. Comparisons of plate counts of actively growing and inactive cells confirmed that coccoid cells are probably nonviable. 相似文献
57.
Conversion of Dexon (p-Dimethylaminobenzenediazo Sodium Sulfonate) to N,N-Dimethyl-p-Phenylenediamine by Pseudomonas fragi Bk9 下载免费PDF全文
N. G. K. Karanth S. G. Bhat C. S. Vaidyanathan V. N. Vasantharajan 《Applied microbiology》1974,27(1):43-46
The metabolism of the fungicide Dexon (p-dimethylaminobenzenediazo sodium sulfonate) by a soil bacterium is reported for the first time. The organism which is capable of using Dexon only by a co-metabolic process was obtained by enrichment culture and was identified as Pseudomonas fragi. The first metabolic product of Dexon was identified as N,N-dimethyl-p-phenylenediamine. The presence of an enzyme, p-dimethylaminobenzenediazo sodium sulfonate reductase, capable of reducing Dexon to N,N-dimethyl-p-phenylenediamine has been demonstrated in the cell-free extracts of the organism. The enzyme is found to be in the soluble fraction and requires dithiothreitol as a reductant. 相似文献
58.
Value of cane trash in nitrogen nutrition of sugarcane 总被引:1,自引:0,他引:1
The significance of trash containing 0.3 to 0.5% N in the N nutrition of sugarcane (Saccharum hybrid sp.) was investigated in pot- and field experiments using15N-labelled trash. The data obtained from the pot study with 2 silty-clay loams (a Humic Nitosol and a Humic Acrisol) showed
that surface-applied trash (10 tonnes/ha), although ground to pass a 1-mm sieve, contributed less than 10% of N removed by
sugarcane. Uptake of trash N was most active during the initial 6 months of the experiment though at the end of the study
period of 18 months less than 15% of trash N was altogether recovered by sugarcane.
In the absence of fertilizer N in a field study on the Humic Acrisol (C/N ratio 22), unground trash (5 tonnes. ha−1) depressed soil N uptake by sugarcane by immobilizing available soil N. The field study moreover confirmed that the contribution
of trash N in the supply of N to sugarcane is negligible. The value of trash would reside in its capacity to increase over
the long term the organic matter level in the soils. 相似文献
59.
The culture supernatant ofPseudomonas
tralucida (Ptm+ strain) produces an agent which can emulsify the insecticide hexachlorocyclohexane (HCH), which was secreted by resting cells. Emulsifying agent is most active with -HCH, and has some activity towards other chlorinated and phosphatic insecticides. The emulsifier is a heat stable macromolecule and associated with growth of the organism on -HCH. 相似文献
60.
目的:尝试应用RNA干扰(RNAi)沉默猪源PK-15细胞中的猪内源性反转录病毒(PERV),并通过反转录酶活性及pol基因相对荧光定量PCR检测沉默效果。方法:依据GenBank公布的PERV pol基因序列,采用Invitro-gen公司的BLOCK-iT RNAi Designer软件设计Stealth小干扰RNA(siRNA)序列;将合成的siRNA转染PK-15细胞,72 h后检测细胞上清PERV反转录酶活性及细胞内pol基因拷贝数并评价沉默效果。结果:反转录酶活性及pol基因拷贝数检测结果表明,设计的3条Stealth siRNA序列中,位于pol基因3272~3296 bp的序列能有效沉默PERV。结论:RNAi方法可有效使猪源PK-15细胞中的PERV沉默,为进一步研究天然抗病毒分子与PERV的相互作用提供了实验基础,同时也为猪源异种移植研究中去除PERV提供了一种可供尝试的方法。 相似文献