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1.
Evaluation of a commercial beta-glucuronidase test for the rapid and economical identification of Escherichia coli 总被引:4,自引:0,他引:4
A commercial beta-glucuronidase (beta-GUR) test for the rapid and economical identification of Escherichia coli was evaluated. A total of 762 clinical strains and 228 environmental isolates were studied. More than 95% of the E. coli strains were found to be beta-GUR positive. Thirty-one clinical isolates of Shigella sonnei, 10 of Enterobacter cloacae, eight of Enterobacter aerogenes, nine of Citrobacter freundii and one of Salmonella enteritidis also gave positive results. The enzyme beta-GUR was also detected in two environmental strains of E. cloacae and one C. freundii. A comparative study between the beta-GUR test and the conventional identification system was carried out in 233 consecutive isolates of lactose positive enterobacteria. Agreement was observed in 223 cases and 190 E. coli strains were correctly identified using this test. Discrepancies were found in 10 cases: nine E. coli were beta-GUR negative and one C. freundii was beta-GUR positive. Escherichia coli was the only species positive for both beta-GUR and indole tests. This procedure permits a rapid, easy, precise and inexpensive identification of E. coli. beta-GUR positive Enterobacter strains have not previously been described. 相似文献
2.
M. Berrocal S. Huerta J. Rodríguez M. Pérez-Leblic M. E. Arias 《World journal of microbiology & biotechnology》1996,12(1):101-102
In surface cultures of Streptomyces cyaneus var. viridochromogenes, NaCl depressed water activity (a
w) without supporting growth. Reducing a
w from 0.987 to 0.951 led to 3- and 4-fold increases in intracellular and extracellular phenol oxidase activities, respectively. 相似文献
3.
The analysis of handsheets from wheat straw following solid substrate fermentation by Streptomyces cyaneus and soda cooking treatment 总被引:1,自引:0,他引:1
Berrocal MM Rodríguez J Hernández M Pérez MI Roncero MB Vidal T Ball AS Arias ME 《Bioresource technology》2004,94(1):27-31
The recent interest in the utilisation of agricultural fibres has promoted research into their potential as raw materials for the pulp and paper industry. In the current study, we report on the effect of biological pretreatment of wheat straw by Streptomyces cyaneus on the performance of the handsheets produced from the treated pulps. The pre-treatment of wheat straw with S. cyaneus had a positive effect on both the burst and tear indexes of the pulps but had a negative impact on tensile index. No significant variation in permeability and in folding endurance was observed. Manipulation of handsheets from wheat straw through biological treatment may therefore result in improved quality traits. 相似文献
4.
Zhang T Berrocal JG Yao J DuMond ME Krishnakumar R Ruhl DD Ryu KW Gamble MJ Kraus WL 《The Journal of biological chemistry》2012,287(15):12405-12416
NMNAT-1 and PARP-1, two key enzymes in the NAD(+) metabolic pathway, localize to the nucleus where integration of their enzymatic activities has the potential to control a variety of nuclear processes. Using a variety of biochemical, molecular, cell-based, and genomic assays, we show that NMNAT-1 and PARP-1 physically and functionally interact at target gene promoters in MCF-7 cells. Specifically, we show that PARP-1 recruits NMNAT-1 to promoters where it produces NAD(+) to support PARP-1 catalytic activity, but also enhances the enzymatic activity of PARP-1 independently of NAD(+) production. Furthermore, using two-photon excitation microscopy, we show that NMNAT-1 catalyzes the production of NAD(+) in a nuclear pool that may be distinct from other cellular compartments. In expression microarray experiments, depletion of NMNAT-1 or PARP-1 alters the expression of about 200 protein-coding genes each, with about 10% overlap between the two gene sets. NMNAT-1 enzymatic activity is required for PARP-1-dependent poly(ADP-ribosyl)ation at the promoters of commonly regulated target genes, as well as the expression of those target genes. Collectively, our studies link the enzymatic activities of NMNAT-1 and PARP-1 to the regulation of a set of common target genes through functional interactions at target gene promoters. 相似文献
5.
Sílvia Jovells-Vaqué Israel García-Paredes Marc Furió Chiara Angelone Lars W. Van den Hoek Ostende Mariona Berrocal Barberà 《Historical Biology》2018,30(3):404-421
AbstractThe Valles-Penedes Basin (Catalonia, Spain) is classical area for the study of Miocene land mammal faunas. Nevertheless, the early Miocene part of the record has deserved little attention as compared to younger intervals. Most notably, the small mammals of this age have not been described in detail, consequently hampering the correlation of the Valles-Penedes record with other chronological schemes. In this work we describe the rich and diverse small mammal fauna from Les Cases de la Valenciana site (Gelida, Alt Penedès) which includes marsupials, eulipotyphlans, lagomorphs and rodents. On the basis of the presence of the cricetids Megacricetodon and Democricetodon this site is correlated with European Neogene zone MN4, yielding an age of 17–16 Ma. However, the rodent assemblage is comparable to that of chronologically close localities of the Calatayud-Montalbán Basin (Aragon, Spain), indicating that the same biochronological scheme can be applied to both areas. In this way, the coexistence of the eomyids Ligerimys ellipticus and Ligerimys florancei coupled with the presence of Megacricetodon primitivus indicates a correlation with local biozone Ca of the Calatayud-Montalban Basin, ranging from 16.3 to 16 Ma. Finally, the correlation of other early Miocene sites of the Valles-Penedes Basin is discussed and refined. 相似文献
6.
We have examined the effects of herbivore diversity on parasitoid community persistence and stability, mediated by nonspecific information from herbivore‐infested plants. First, we investigated host location and patch time allocation in the parasitoid Cotesia glomerata in environments where host and/or nonhost herbivores were present on Brassica oleracea leaves. Parasitoids were attracted by infochemicals from leaves containing nonhost herbivores. They spent considerable amounts of time on such leaves. Thus, when information from the plant is indistinct, herbivore diversity is likely to weaken interaction strengths between parasitoids and hosts. In four B. oleracea fields, all plants contained herbivores, often two or more species. We modelled parasitoid–herbivore communities increasing in complexity, based on our experiments and field data. Increasing herbivore diversity promoted the persistence of parasitoid communities. However, at a higher threshold of herbivore diversity, parasitoids became extinct due to insufficient parasitism rates. Thus, diversity can potentially drive both persistence and extinctions. 相似文献
7.
AD (Alzheimer's disease) is an age-associated neurodegenerative disorder where the accumulation of neurotoxic Aβ (amyloid β-peptide) in senile plaques is a typical feature. Recent studies point out a relationship between Aβ neurotoxicity and Ca2+ dyshomoeostasis, but the molecular mechanisms involved are still under discussion. The PMCAs (plasma membrane Ca2+-ATPases) are a multi-isoform family of proteins highly expressed in brain that is implicated in the maintenance of low intraneural Ca2+ concentration. Therefore the malfunction of this pump may also be responsible for Ca2+ homoeostasis failure in AD. We have found that the Ca2+-dependence of PMCA activity is affected in human brains diagnosed with AD, being related to the enrichment of Aβ. The peptide produces an inhibitory effect on the activity of PMCA which is isoform-specific, with the greatest inhibition of PMCA4. Besides, cholesterol blocked the inhibitory effect of Aβ, which is consistent with the lack of any Aβ effect on PMCA4 found in cholesterol-enriched lipid rafts isolated from pig brain. These observations suggest that PMCAs are a functional component of the machinery that leads to Ca2+ dysregulation in AD and propose cholesterol enrichment in rafts as a protector of the Aβ-mediated inhibition on PMCA. 相似文献
8.
Kristine M. Frizzell Matthew J. Gamble Jhoanna G. Berrocal Tong Zhang Raga Krishnakumar Yana Cen Anthony A. Sauve W. Lee Kraus 《The Journal of biological chemistry》2009,284(49):33926-33938
Poly(ADP-ribose) polymerase-1 (PARP-1) and poly(ADP-ribose) glycohydrolase (PARG) are enzymes that modify target proteins by the addition and removal, respectively, of ADP-ribose polymers. Although a role for PARP-1 in gene regulation has been well established, the role of PARG is less clear. To investigate how PARP-1 and PARG coordinately regulate global patterns of gene expression, we used short hairpin RNAs to stably knock down PARP-1 or PARG in MCF-7 cells followed by expression microarray analyses. Correlation analyses showed that the majority of genes affected by the knockdown of one factor were similarly affected by the knockdown of the other factor. The most robustly regulated common genes were enriched for stress-response and metabolic functions. In chromatin immunoprecipitation assays, PARP-1 and PARG localized to the promoters of positively and negatively regulated target genes. The levels of chromatin-bound PARG at a given promoter generally correlated with the levels of PARP-1 across the subset of promoters tested. For about half of the genes tested, the binding of PARP-1 at the promoter was dependent on the binding of PARG. Experiments using stable re-expression of short hairpin RNA-resistant catalytic mutants showed that PARP-1 and PARG enzymatic activities are required for some, but not all, target genes. Collectively, our results indicate that PARP-1 and PARG, nuclear enzymes with opposing enzymatic activities, localize to target promoters and act in a similar, rather than antagonistic, manner to regulate gene expression. 相似文献
9.
M. M. Berrocal J. Rodríguez A. S. Ball M. I. Pérez-Leblic M. E. Arias 《Applied microbiology and biotechnology》1997,48(3):379-384
Nine Streptomyces strains were screened for their ability to solubilise and mineralise 14C-labelled lignin during growth in solid-state fermentation. Streptomyces viridosporus was confirmed as an active lignin-degrading organism along with a new isolate, Streptomyces sp. UAH 15, further classified as Streptomyces cyaneus CECT 3335. This organism was able to solubilise and mineralise the [14C]lignin fraction of lignocellulose (44.96 ± 1.77% and 3.41 ± 0.48% respectively) after 21 days of incubation. Cell-free filtrates
from Streptomyces sp. grown in solid-state fermentation were capable of solubilising up to 20% of the [14C]lignin after 2 days incubation, with most of the product detected in the acid-soluble rather than in the water-soluble fraction.
Identification of the extracellular enzymes produced during growth of S. cyaneus CECT 3335 revealed that extracellular peroxidase and phenol oxidase activities were present, with the activity of phenol
oxidase being 100 times greater than peroxidase activity. The activity of these two enzymes was found to correlate with both
solubilisation and mineralisation rates. This is the first report of phenol oxidase activity produced by a Streptomyces strain during growth in solid-state fermentation. A role for the enzyme in the solubilisation and mineralisation of lignocellulose
by S. cyaneus is suggested.
Received: 12 May 1997 / Accepted: 19 May 1997 相似文献
10.