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841.
842.
SYNOPSIS. Isoenzyme electrophoresis of 7 different enzyme systems was used to compare 24 strains of Naegleria fowleri and 6 strains of N. gruberi. The 30 strains could be grouped into 4 distinct categories based upon zymogram patterns. No interstrain band variation in all enzyme systems was demonstrated in pathogenic strains of N. fowleri. Three nonpathogenic high temperature-tolerant strains of Naegleria had similar zymograms. Four of the 5 remaining nonpathogenic Naegleria strains had no interstrain band variation. Based upon zymograms, the 22 pathogenic strains constitute a homogenous species. Similarly the high temperature-tolerant nonpathogenic strains formed a cohesive group. The remaining nonpathogenic strains could be separated into 2 groups. 相似文献
843.
Uptake hydrogenase activity in nodules of green gram (Vigna radiata (L.) (Wilczek)), black gram (Vigna mungo (L.) (Hepper)), cowpea (Vigna unguiculata (L.) and cluster bean (Cyamopsis tetragonoloba (L.) (Taub.)), formed with two Hup+ (S24 and CT2014) and one Hup− (M11)Rhizobium strains, was determined at different levels of external H2 in air atmosphere. Nodules of all the 4 host species formed by
inoculation with strains S24 and CT2014, showed H2 uptake but not those formed with strain M11. H2 uptake rates were higher in 1 and 2% H2 in air atmosphere (v/v) than at 5 or 10% levels in all the host species. Variations in the relative rates of H2 uptake were observed both, due to host species as well as due toRhizobium strains. However, no host dependent complete repression of the expression of H2 uptake activity was observed in nodules of any of the host species formed with Hup+ strains. 相似文献
844.
AGATA SIEDLECKA MIRELA J. WOLF-BACA KATARZYNA PIEKARSKA 《Polish journal of microbiology》2021,70(1):57
Although antibiotic-resistant bacteria (ARB) have been isolated from tap water worldwide, the knowledge of their resistance patterns is still scarce. Both horizontal and vertical gene transfer has been suggested to contribute to the resistance spread among tap water bacteria. In this study, ARB were isolated from finished water collected at two independent water treatment plants (WTPs) and tap water collected at several point-of-use taps during summer and winter sampling campaigns. A total of 24 strains were identified to genus or species level and subjected to antibiotic and disinfectant susceptibility testing. The investigated tap water ARB belonged to phyla Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes. The majority of the isolates proved multidrug resistant and resistant to chemical disinfectant. Neither seasonal nor WTP-dependent variabilities in antibiotic or disinfectant resistance were found. Antibiotics most effective against the investigated isolates included imipenem, tetracyclines, erythromycin, and least effective – aztreonam, cefotaxime, amoxicillin, and ceftazidime. The most resistant strains originate from Afipia sp. and Methylobacterium sp. Comparing resistance patterns of isolated tap water ARB with literature reports concerning the same genera or species confirms intra-genus or even intra-specific variabilities of environmental bacteria. Neither species-specific nor acquired resistance can be excluded. 相似文献
845.
Lorena Latorre-García Ana Cristina Adam Julio Polaina 《World journal of microbiology & biotechnology》2008,24(12):2957-2963
Production of glucoamylase encoded by the Saccharomyces cerevisiae (var. diastaticus) STA1 gene has been assayed in laboratory S. cerevisiae strains of different ploidy and in different industrial Saccharomyces strains, in which STA1 was expressed under control of an inducible promoter. Highest enzyme activity was achieved with a tetraploid strain constructed
by crossing preselected parental strains. Maximal glucoamylase production correlated with heterogeneity in enzyme mass, likely
due to incomplete glycosylation, suggesting that the secretion-glycosylation process is the limiting step in the production
of the STA-encoded glucoamylase by Saccharomyces. Industrial strains showed quite different capacity to produce glucoamylase. High production was achieved with a S. pastorianus brewer’s strain. Overall, our results allowed the selection of strains capable of yielding a high level of glucoamylase and
suggest specific approaches for further enhancing this capability. 相似文献
846.
Danielle Caroline Manenti Jackson Araújo Matheus Hideki Kihara Maeda Moana Lima Tavares-Esashika Paulo Hugo Aguiar Anderson Rotter Meda Tatsuya Nagata Eliezer Rodrigues de Souto 《The Annals of applied biology》2023,182(2):216-225
Cotton blue disease (CBD) and atypical-CBD are the most important viral diseases of cotton plants in the southern region of South America. Common and atypical strains of cotton leafroll dwarf virus (CLRDV and CLRDV-at, respectively) are thought to be causative agents of CBD and atypical-CBD, respectively. Inoculation of test plants via aphid vectors is difficult, as is determining strains via molecular diagnosis; accordingly, it is difficult for breeders to evaluate the effects of blue disease-associated virus infections in cotton lineages. In the present study, we attempted to circumvent these difficulties by producing six full-length cDNA infectious clones from CLRDV and CLRDV-at strains using the Gibson Assembly protocol. For inoculation of the infectious clones, a vacuum chamber-mediated agroinfiltration protocol was adapted and applied. Using this protocol, 90%–100% of cotton plants became infected with the clones, which was not possible via syringe-based agroinfiltration. A genotyping protocol based on RT-qPCR targeting a specific region of the virus P0 protein was also developed, allowing rapid differentiation of CLRDV and CLRDV-at. Applying this protocol to 68 field samples revealed that CLRDV-at was dominant (50%) over CLRDV (5.8%) in single virus infections. These preliminary results imply that CLRDV-at might occupy the ecological niche of CLRDV in the cotton fields of Brazil. 相似文献
847.
《Biologicals》2014,42(2):123-127
In Poland, where the wP vaccine has been used since 1960, pertussis rates increased in the mid-1990s. In 2012, the rate of pertussis recognised by surveillance was unexpectedly found to be two-fold higher than in the previous decade. Quality measures on potency and vaccine working seeds were introduced, to confirm the possible impact of manufacturing inconsistency or potency lowering on the observed increase in pertussis. Shewhart charts on potency values for lots released between 2001 and 2013 did not reveal any significant fluctuations. Working seeds of three vaccine strains used within last decade for wP manufacturing belong to the PFGE group III and were highly related. According to PFGE and SDS-PAGE data, all vaccine strains were found consistent according profiling on the genomic and protein levels. According to the sequencing data, they harboured ptxA2, ptxC1, prn1, fim2-1, fim3-1, tcfA2, ptxP1 and were assigned as MLST-2 type. Other factors apart from vaccine manufacturing inconsistency might be responsible for the increase in pertussis noted in 2012 in Poland. 相似文献
848.
Jesus Ramirez-Santos Gloria Alvarez Elvia Cisneros M.Carmen Gomez-Eichelmann 《FEMS microbiology letters》1992,93(2):189-193
The presence of insertion sequence IS1 in 70 multiple-antibiotic resistant clinical strains was determined. This 70-strain collection comprised 46 Escherichia coli, 18 Salmonella and 6 Shigella strains. The presence of IS1 was detected in the chromosome and plasmids of 73% and 63% of the strains, respectively, and 51% of the strains carried IS1 in both. The frequency of IS1 was higher in Salmonella than in E. coli and Shigella strains. A total of 31 strains carried large plasmids with IS1; 10 of these strains (32.3%) were able to transfer all or some of the antibiotic resistance markers to E. coli K12 or S. typhimurium recipient strains. Resistance markers of all clinical strains were maintained stably after several generations of growth. The presence of IS1 in a relatively high percentage of plasmids of multiple-antibiotic resistant clinical isolates, suggests a role for this sequence in the dissemination of genes which code for antibiotic resistance. 相似文献
849.
Molecular approaches towards development of novel Bacillus thuringiensis biopesticides 总被引:4,自引:0,他引:4
Bacillus thuringiensis (Bt) has been used for control of lepidopteran, dipteran and coleopteran insects for over three decades. Novel Bt strains
harbouring new types of insecticidal genes are being discovered worldwide. Recombinant strains with enhanced toxicity and
broadened insecticidal spectrum have been constructed. To increase the field persistence of insecticidal crystal proteins
(ICPs), alternative modes of their delivery in Pseudomonas sp. and endophytes have been developed. ICPs have been modified by site-directed mutagenesis to improve their insecticidal
efficacy. Higher yields of ICPs have been achieved by use of strong expression promoters and other regulatory elements. Gene-disabling
of the sporulation-specific protease has led to yield enhancement of ICPs. Interestingly, Bt toxins have been found to act
synergistically with some other pesticidal agents. Optimization of fermentation conditions is an essential requirement for
cost-effective commercial production of Bt biopesticides. The environmental impact of deployment of genetically engineered
biopesticides has been assessed. Recombinant Bt strains that do not carry any non-Bt DNA, endophytes, encapsulation in killed
bacteria (such as Pseudomonas) and asporogenous Bt strains are ecologically safe approaches. Efficient resistance management strategies require judicious
use of Bt transgenic plants in conjunction with refugia and Bt biopesticides in an Integrated Pest Management (IPM) program.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
850.
Lea K. Bleyman Mary P. Baum Peter J. Bruns Eduardo Orias 《Genesis (New York, N.Y. : 2000)》1992,13(1):34-40
Tetrahymena thermophila has a multiple mating type system. While a sexually mature cell usually expresses only one mating type, its germline (micronucleus) carries the genetic potential for 5 to 7 mating types. The set of allowed mating types is specified by the mat locus. The choice of which particular mating type is expressed by a cell reflects a somatically inherited, developmentally programmed differentiation of the somatic nucleus (macronucleus). In this work we report that the mat locus maps to the left arm of chromosome 2, as determined by nullisomic deletion mapping. We also report a distance of 29 cM between the mat locus and the ribosomal RNA gene, previously mapped to chromosome 2L. This represents another (rare) case of meiotic linkage in Tetrahymena. © 1992 Wiley-Liss, Inc. 相似文献