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51.
Junaid Akhtar Ani Idris Ramlan Abd. Aziz 《Applied microbiology and biotechnology》2014,98(3):987-1000
Production of succinic acid via separate enzymatic hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) are alternatives and are environmentally friendly processes. These processes have attained considerable positions in the industry with their own share of challenges and problems. The high-value succinic acid is extensively used in chemical, food, pharmaceutical, leather and textile industries and can be efficiently produced via several methods. Previously, succinic acid production via chemical synthesis from petrochemical or refined sugar has been the focus of interest of most reviewers. However, these expensive substrates have been recently replaced by alternative sustainable raw materials such as lignocellulosic biomass, which is cheap and abundantly available. Thus, this review focuses on succinic acid production utilizing lignocellulosic material as a potential substrate for SSF and SHF. SSF is an economical single-step process which can be a substitute for SHF — a two-step process where biomass is hydrolyzed in the first step and fermented in the second step. SSF of lignocellulosic biomass under optimum temperature and pH conditions results in the controlled release of sugar and simultaneous conversion into succinic acid by specific microorganisms, reducing reaction time and costs and increasing productivity. In addition, main process parameters which influence SHF and SSF processes such as batch and fed-batch fermentation conditions using different microbial strains are discussed in detail. 相似文献
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A. S. Alhomida A. S. Duhaiman A. A. Al-Jafari M. A. Junaid 《Molecular and cellular biochemistry》1996,165(2):95-101
The enzyme carnitine acetyltransferase (CAT) catalyzes the reversible transfer of short-chain acyl groups between coenzyme A and L-carnitine, and hence, plays an important role in the -oxidation of fatty acids. Purification and characterization of CAT from desert animal species may help in explaining the involvement of secondary pathways for energy production in these species. In this paper, we report the purification and partial characterization of CAT from the Arabian camel. CAT was purified from the skeletal muscle of the Arabian camel by ammonium sulfate and acetone fractionation, followed by chromatography on DEAF-Sepharose, agarose-Co A and Superose 12 gel filtration columns. CAT was purified by 2937-fold to a specific activity of 94 Units mg–1. The purified CAT was a monomer of 59 kDa as judged by native and SDS-PAGE, and showed a pl of 5.2. The enzyme displayed maximum activity with propionyl-Co A. Apparent Km for acetyl-, propionyl- and butyryl-Co A were 27.7, 17.3 and 29 M respectively, while palmitoyl-Co A was not a substrate. 相似文献
55.
Direct evidence for the excitotoxicity of -N-oxalyl-L-,-diaminopropionic acid (ODAP), the Lathyrus sativus neurotoxin has been studied by examining the binding of chemically synthesized [2,3 3H]ODAP ([3H]ODAP) to synaptic membranes. [3H]ODAP binding to membranes was mostly nonspecific, with only a very low specific binding (15–20% of the total binding) and was also not saturable. The low specific binding of [3H]ODAP remained unaltered under a variety of assay conditions. A low Bmax of 3.2 ± 0.4 pmol/mg and Kd 0.2 ± 0.08 M could be discerned for the high affinity interactions under conditions wherein more than 80–90% of the binding was nonspecific. While ODAP could inhibit the binding of [3H]glutamate to chick synaptic membranes with a Ki of 10 ± 0.9 M, even L-DAP, a non neurotoxic amino acid was also equally effective in inhibiting the binding of [3H]glutamate. The very low specific binding of [3H]ODAP to synaptic membranes thus does not warrant considering its interactions at glutamate receptors as a significant event. The results thus suggest that the reported in vitro excitotoxic potential of ODAP may not reflect its true mechanism of neurotoxicity. 相似文献
56.
Synthesis of cubic ZnS microspheres exhibiting broad visible emission for bioimaging applications
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Biocompatible ZnS microspheres with an average diameter of 3.85 µm were grown by solvo‐hydrothermal (S‐H) method using water–acetonitrile–ethylenediamine (EDA) solution combination. ZnS microspheres were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), high‐resolution transmission electron microscopy (HRTEM), Fourier transform (FT)‐Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) techniques. The broad photoluminescence (PL) emissions from 380–580 nm that were seen from the ZnS microspheres attributed to the increase in carrier concentration, as understood from the observed intense Raman band at 257 cm–1. Cytotoxicity and haemocompatibility investigations of these ZnS microspheres revealed its biocompatibility. ZnS microspheres, along with biological cell lines, were giving visible light emission and could be used for bioimaging applications. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Toxicity of Thiophenes from Echinops transiliensis (Asteraceae) against Aedes aegypti (Diptera: Culicidae) Larvae
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Hiroshi Nakano Abbas Ali Junaid Ur Rehman Leonid K. Mamonov Charles L. Cantrell Ikhlas A. Khan 《化学与生物多样性》2014,11(7):1001-1009
Structure? activity relationships of nine thiophenes, 2,2′: 5′,2″‐terthiophene ( 1 ), 2‐chloro‐4‐[5‐(penta‐1,3‐diyn‐1‐yl)thiophen‐2‐yl]but‐3‐yn‐1‐yl acetate ( 2 ), 4‐(2,2′‐bithiophen‐5‐yl)but‐3‐yne‐1,2‐diyl diacetate ( 3 ), 4‐[5‐(penta‐1,3‐diyn‐1‐yl)thiophen‐2‐yl]but‐3‐yne‐1,2‐diyl diacetate ( 4 ), 4‐(2,2′‐bithiophen‐5‐yl)‐2‐hydroxybut‐3‐yn‐1‐yl acetate ( 5 ), 2‐hydroxy‐4‐[5‐(penta‐1,3‐diyn‐1‐yl)thiophen‐2‐yl]but‐3‐yn‐1‐yl acetate ( 6 ), 1‐hydroxy‐4‐[5‐(penta‐1,3‐diyn‐1‐yl)thiophen‐2‐yl]but‐3‐yn‐2‐yl acetate ( 7 ), 4‐(2,2′‐bithiophen‐5‐yl)but‐3‐yne‐1,2‐diol ( 8 ), and 4‐[5‐(penta‐1,3‐diyn‐1‐yl)thiophen‐2‐yl]but‐3‐yne‐1,2‐diol ( 9 ), isolated from the roots of Echinops transiliensis, were studied as larvicides against Aedes aegypti. Structural differences among compounds 3, 5 , and 8 consisted in differing AcO and OH groups attached to C(3″) and C(4″), and resulted in variations in efficacy. Terthiophene 1 showed the highest activity (LC50, 0.16 μg/ml) among compounds 1 – 9 , followed by bithiophene compounds 3 (LC50, 4.22 μg/ml), 5 (LC50, 7.45 μg/ml), and 8 (LC50, 9.89 μg/ml), and monothiophene compounds 9 (LC50, 12.45 μg/ml), 2 (LC50, 14.71 μg/ml), 4 (LC50, 17.95 μg/ml), 6 (LC50, 18.55 μg/ml), and 7 (LC50, 19.97 μg/ml). These data indicated that A. aegypti larvicidal activities of thiophenes increase with increasing number of thiophene rings, and the most important active site in the structure of thiophenes could be the tetrahydro‐thiophene moiety. In bithiophenes, 3, 5 , and 8 , A. aegypti larvicidal activity increased with increasing number of AcO groups attached to C(3″) or C(4″), indicating that AcO groups may play an important role in the larvicidal activity. 相似文献
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Ashraf A. Khan Elizabeth Ponce M. S. Nawaz Chorng-Ming Cheng Junaid A. Khan Christine S. West 《Applied and environmental microbiology》2009,75(4):1192-1196
A total of 210 Salmonella isolates, representing 64 different serovars, were isolated from imported seafood samples, and 55/210 isolates were found to be resistant to at least one antibiotic. Class 1 integrons from three multidrug-resistant Salmonella enterica strains (Salmonella enterica serovars Newport [strain 62], Typhimurium var. Copenhagen [strain 629], and Lansing [strain 803], originating from Hong Kong, the Philippines, and Taiwan, respectively) were characterized. Southern hybridization of plasmids isolated from these strains, using a class 1 integron probe, showed that trimethoprim-sulfamethoxazole and streptomycin resistance genes were located on a megaplasmid in strain 629. Our study indicates that imported seafood could be a reservoir for Salmonella isolates resistant to multiple antibiotics.Salmonella spp. are recognized as major food-borne pathogens of humans worldwide. In the United States, there are an estimated 800,000 to 4 million Salmonella infections annually, and approximately 500 of the cases are fatal (8, 26). A variety of foods have been implicated as vehicles transmitting salmonellosis to humans, including poultry, beef, pork, eggs, milk, cheese, fish, shellfish, fruits, juice, and vegetables (1, 4, 9, 12, 23). Previous studies by field laboratories of the U.S. Food and Drug Administration have shown the prevalences of Salmonella isolates in imported and domestic seafood as 7.2% and 1.3%, respectively (6, 11, 27).Mobile genetic elements, such as plasmids, transposons, and integrons, which disseminate antibiotic resistance genes by horizontal or vertical transfer, as part of either resistance plasmids or conjugative transposons, play an important role in the evolution and dissemination of multidrug resistance (2, 3, 10, 17). Salmonella genomic island 1 (SGI1), the first genomic island reported to contain an antibiotic resistance gene cluster, was identified in the multidrug-resistant Salmonella enterica serovar Typhimurium strain DT 104 (21).Most studies of the prevalence and characterization of antimicrobial resistance genes and integrons in Salmonella spp. have focused on strains from clinical and veterinary sources. However, little is known about the occurrence of SGI1 and its variants in Salmonella spp. isolated from seafood. We have screened a set of drug-resistant S. enterica strains from seafood belonging to 64 different serovars for SGI1 and class 1 integron conserved sequences (CS). We report the presence of a class I variant integron carrying the dfrXII and aadA2 genes on a megaplasmid in serovar Typhimurium var. Copenhagen and on the chromosome in Salmonella enterica serovar Lansing. We also found the variant class 1 integron carrying the dfrA1 and orfC genes in Salmonella enterica serovar Newport strains from seafood.A total of 210 Salmonella enterica strains isolated from seafood imported into the United States between 2000 and 2005 were identified and serotyped by the Pacific Regional Laboratory-Southwest of the FDA, Irvine, CA. The Salmonella strains represented 20 serogroups (Table (Table1)1) from various imported seafood items. The Salmonella strains were tested with 16 antibiotics (14) commonly used in either human or veterinary medicine on Mueller-Hinton agar (Difco Laboratories, Detroit, MI), using a disk diffusion method. The sensitivity and resistance were determined by the criteria of the Clinical and Laboratory Standards Institute (1999).
Open in a separate windowAll Salmonella strains that were resistant to three or four antibiotics and trimethoprim were screened by PCR for the presence of class 1 integrons, using the CSL1 and CSR1 primers (Table (Table2)2) (14). To confirm other antibiotic resistance genes, we used primers and PCR methods described previously (13, 14, 16). To identify SGI1 in multidrug-resistant strains, PCR was performed by using primers U7-L12/LJ-R1 and 104-RJ/104-D (Table (Table2),2), corresponding to the left and right junctions of SGI1 in the Salmonella chromosome, respectively (16). For a positive control, serovar Typhimurium DT104 strain DT7 (13) was used. As a negative control, Escherichia coli cells or DNA was used. A reagent blank included in each PCR contained distilled water instead of template DNA. For sequencing, the PCR-amplified integrons were purified and cloned into plasmid vector pCR2.1 (Invitrogen Corp., Carlsbad, CA). The clones were investigated for the presence of inserts by isolating the recombinant plasmid, which was confirmed by digestion with the restriction enzyme EcoRI. Sequencing of both strands was performed. DNA sequences were analyzed with Lasergene (DNASTAR, Inc., Madison, WI) software. Oligonucleotide primers and probes were purchased from MWG Biotech (High Point, NC).
Open in a separate windowPlasmid DNA was isolated using an alkaline lysis method with modifications described previously (19). Plasmids were separated by electrophoresis in 1× Tris-acetate-EDTA buffer at 64 V for 2 h on 1.0% agarose gels, stained with 40 μl of ethidium bromide (0.625 mg/ml) for visualization, and then transferred and cross-linked to positively charged nylon membranes (Roche, Indianapolis, IN). The resulting blots were hybridized at 65°C for 18 h with digoxigenin-labeled DNA probes (1.2-kb and 1.9-kb PCR-amplified products), using CSL1 and CSR1 primers specific for class 1 integrons (22). 相似文献
TABLE 1.
Salmonella serotypes isolated from imported foodsNo. of strains | S. enterica serovar(s) or Salmonella group(s) |
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39 | Weltevreden |
16 | Newport |
13 | Saintpaul |
10 | Senftenberg |
8 | Lexington |
7 | Virchow |
6 | Enteritidis, Bareily |
5 | Bovismorbificans, Brunei, Java, Hvittingfoss |
4 | Paratyphi B var. Java, Thompson |
3 | Aberdeen, Cubana, Stanley, Derby, Lansing |
2 | Montevideo, Hadar, Agona, San Diego, Braenderup, Lanka, Salmonella enterica subsp. diarizonae, Oslo, Bareily variant, Salmonella monophasic group C2 |
1 | Ouakam, Cannstatt, Albany, Newport/Bardo, Adelaide, S. enterica subsp. diarizonae, Houten, Giza, Miami, Onderstepoof, Infantis, Salmonella monophasic group D1, Mbandaka, Salmonella monophasic group G2, Ohio, Rutgers, Salmonella monophasic group D2, Amsterdam, Salmonella enterica subsp. IV serotype 43:z4z23, Paratyphi B var. Java, Wentworth, Potsdam, Muenster var. 15+, 34+, Lexington var. 15+, Weltevreden var. 15+, S. enterica subsp. I, Madella, Alachua, London, Singapore, Uphill, Thielallee, Typhimurium var. Copenhagen |
TABLE 2.
Primer pairs for integron PCR and sequencingPrimer | Sequence (5′-3′) | Location | PCR product size (bp) |
---|---|---|---|
CSL1 | GGC ATC CAA GCA GCA AGC | 5′ CS | |
CSR1 | AAG CAG ACT TGA CCT GAT | 3′ CS | |
U7-L12 | ACA CCT TGA GCA GGG CAA AG | thdF | 500 |
LJ-R1 | AGT TCT AAA GGT TCG TAG TCG | ||
104-RJ | TGA CGA GCT GAA GCG AAT TG | S044 | |
104D | ACC AGG GCA AAA CTA CAC AG | yidY | |
aadA2F | TGT TGG TTA CTG TGG CCG TA | aadA2 | 380 |
aadA2R | GCT GCG AGT TCC ATA GCT TC |
60.
High frequency of shoot formation was achieved from Solanum nigrum L. leaves on Murashige and Skoog (MS) medium without any callusing stage. Shoot forming ability was more pronounced on leaves
positioned dorsally. For shoot induction, 2.0 mg dm−3 benzylaminopurine and 1.5 mg dm−3 kinetin were observed to be the most effective plant growth regulators (PGRs). The present paper also describes first successful
induction of in vitro flowering in S. nigrum. The leaf derived shoots were excised and treated with various root promoting PGRs and 0.25 mg dm−3 indole-3-butyric acid produced maximum number of roots (15.2 per plant). Plants were later transplanted in field with 100
% survival. Solasodine content was higher in in vitro raised shoots and leaf derived callus, compared to ex vitro grown shoots. 相似文献