Determination of serum CA724 levels using fluorescence immunochromatography.

BACKGROUND: Carbohydrate antigen 724 (CA724) is a sensitive and specific indicator for multiple malignant tumors. The aim of this study was to establish a Eu-time resolved fluorescence immunochromatography (Eu-TRFICO) method for quantitative detection of CA724 in serum. METHODS: Eu-TRFICO strips were optimized and assembled. The sensitivity, specificity and precision were evaluated using CA724 standard dilutions and matrix serum. Meanwhile, the reference interval, comparison, and sensitivity/specificity were performed using clinical negative/positive gastric cancer serum samples. RESULTS: The standard curve equation was y = 9.869 x - 154.12 (R2 = 0.993), and the sensitivity was 0.42 U/mL. The common interferents in serum could not affect the quantitative results with low cross-reactivities (all no more than 1.09%). All average recoveries of the intra- and interbatch ranged from 102.38 to 106.40%, and all CVs were below 10%. The reference interval of the healthy subjects was < 4.68 U/mL and the reference interval of the subjects with grade I/II gastric cancer was > 9.54 U/mL. Additionally, a high Pearson r (0.9503) and sensitivity/specificity (92.86%/94.20%) were obtained. CONCLUSION: This study prepared Eu-TRFICO strips with high sensitivity, specificity, precision and satisfactory clinical testing performance, which provides more options for clinical quantitative and convenient testing of CA724.

Temporal Changes in Microbial Metabolic Characteristics in Field-Scale Biopiles Composed of Aged Oil Sludge.

Disposal of oil sludge, a hazardous waste, is currently a prevalent environmental issue. In this study, two field-scale biopiles were constructed to explore the temporal changes of microbial metabolic characteristics during the biotreatment of aged oil sludge. Bulking agent was mixed thoroughly with oily sludge to form a treated pile. The BIOLOG™ system was used to analyze the community level physiological parameters, including microbial metabolic activity, diversity, and variance. In comparison with the control, the community level physiological parameters of the treated pile were dramatically improved. Microbial metabolic activity of the treated pile was improved by 25.06% calculated from the maximums during the treatment. Microbial diversity index (Shannon index) ranges were improved from 1.64-3.02 (control pile) to 2.34-3.14 (treated pile). The numbers of petroleum-degrading bacteria and the total heterotrophic bacteria were correlated with the environmental temperature, and microbial metabolic characteristics in the treated pile revealed the distinctive carbon resources selection with the addition of cotton stalk. Temporal microbial metabolic characteristics, which have important effect on bioremediation, were revealed in this study.

The organization of naphthalene degradation genes in Pseudomonas putida strain AK5.

The Pseudomonas putida АК5 that was isolated from the slime pit of a Nizhnekamsk oil chemical factory can metabolize naphthalene via salicylate and gentisate. Catabolic genes are localized on non-conjugative IncP-7 plasmid pAK5 of about 115 kb in size. The "classical"nah-1 operon and the novel sgp-operon (salicylate-gentisate pathway) are both involved in naphthalene degradation by P. putida АК5, that was first described for Pseudomonas. The sgp-operon includes six open reading frames (ORFs) (sgpAIKGHB). The four ORFs code for the entire salicylate 5-hydroxylase - oxidoreductase component (sgpA), large and small subunits of the oxigenase component (sgpG and sgpH) and 2Fe-2S ferredoxin (sgpB). Genes for gentisate 1, 2-dioxygenase (sgpI) and fumarylpyruvate hydrolase (sgpK) are located in salicylate 5-hydroxylase genes clustering between sgpA and sgpG. The putative positive regulator for the sgp-operon (sgpR) was found upstream of the sgpA gene and oriented in the opposite direction from sgpA. The putative maleylacetoacetate isomerase gene is located apart, directly downstream from the sgp-operon. The sgp-operon organization and phylogenetic analysis of deduced amino acid sequences indicate that this operon has a mosaic structure according to the modular theory of the evolution of modern catabolic pathways.

A cytological characterization of the parasitic action of ultramicrobacteria NF1 and NF3 of the genus Kaistia on chemoorganotrophic and phototrophic bacteria.

Two strains (NF1 and NF3) of free-living chemoorganotrophic bacteria have been isolated from multiyear oil slime and Pedilanthus tithymaloides rhizosphere and ascribed to the genus Kaistia of the class Alphaproteobacteria on the basis of the nucleotide sequences of 16S rRNA gene and phenotypic characteristics. These strains can be assigned to ultramicrobacteria as their populations are represented by two subpopulations: (1) ultrasmall cells, on average 200-300 nm in diameter and <0.1 microm(3) in volume, of up to 60% of the total number of cells in a population, and (2) cells 400-800 nm in diameter and 0.15-0.5 microm(3) in volume, of up to 40% of the total number of cells in a population. The interaction of the isolated ultramicrobacteria strains (IUMB) with different bacterial species has been studied in cocultures grown under starvation and in complete nutrient media. It has been found that IUMB can be facultative parasites on certain species of chemoorganotrophic and phototrophic bacteria. The interaction of IUMB with prey bacteria exhibits the extracellular type of parasitism and involves establishing stable cell-cell contacts between the parasites and their prey to cause destruction of host cells.

Molecular classification of IncP-9 naphthalene degradation plasmids.

A large collection of naphthalene-degrading fluorescent Pseudomonas strains isolated from sites contaminated with coal tar and crude oil was screened for the presence of IncP-9 plasmids. Seventeen strains were found to carry naphthalene catabolic plasmids ranging in size from 83 to 120 kb and were selected for further study. Results of molecular genotyping revealed that 15 strains were closely related to P. putida, one to P. fluorescens, and one to P. aeruginosa. All catabolic plasmids found in these strains, with the exception of pBS216, pSN11, and p8909N-1, turned out to belong to IncP-9 beta-subgroup. Plasmids pBS216, pSN11, and p8909N-1 were identified as members of IncP-9 delta-subgroup. One plasmid, pBS2, contains fused replicons of IncP-9beta and IncP-7 groups. RFLP analyses of the naphthalene catabolic plasmids revealed that organisation of the replicon correlates well with the overall plasmid structure. Comparative PCR studies with conserved oligonucleotide primers indicated that genes for key enzymes of naphthalene catabolism are highly conserved among all studied plasmids. Three bacterial strains, P. putida BS202, P. putida BS3701, and P. putida BS3790, were found to have two different salicylate hydroxylase genes one of which has no similarity to the "classic" enzyme encoded by nahG gene. Discovery of a large group of plasmid with unique nahR suggested that the regulatory loop may also represent a variable part of the pathway for catabolism of naphthalene in fluorescent Pseudomonas spp.

Antagonistic activity among 2,4-diacetylphloroglucinol-producing fluorescent Pseudomonas spp.

Strains of fluorescent Pseudomonas spp. that produce 2,4-diacetylphloroglucinol (2,4-DAPG) differ in their ability to colonize roots. In this study, we screened 47 2,4-DAPG-producing strains representing17 distinct genotypes for antagonistic activity associated with the production of bacteriocins. Upon induction, over 70% of the strains inhibited the growth of other isolates in vitro. Greenhouse assays indicated that populations of sensitive strains in wheat rhizosphere soil declined more rapidly in the presence of antagonists than when introduced alone. Antagonism can influence the ability of biocontrol agents to establish and maintain effective population densities in situ.