Isolation and Phylogenetic Analysis of Plant Pathogen-Inhibiting Strains from Southern Ocean

[Objective] The aim was to isolate the strains resistant to plant pathogenic fungi from Southern Ocean and study their phylogenetic relationship and antimicrobial spectrum. [Method] Agar diffusion method was adopted to screen antimicrobial strains and determine the antimicrobial spectrum. Phylogenetic relationship of the strains was analyzed by neighbor-joining method of the Mega 4.0 software. [Result] Twenty antimicrobial strains were screened from seawater of Southern Ocean collected during the 27^th Chinese Antarctic Scientific Expedition. Molecular identification and phyloge- netic analysis indicated that two antimicrobial strains were members of Pseu- domonas, two strains were members of Psychrobacter, and the other 16 trains were members of Pseudoalteromonas. The antimicrobial spectrum of four strains which had higher antimicrobial activity indicated that the strains 312, 83-1 and 195 greatly inhibited the growth of Fusarium oxysporum, Rhizoctonia solani K（Jhn, Phytophthora capsici Leonian, Verticillium dahliae, Alternaria solani, Thanatephoru scucumeris and Phomopsis asparagi （Sacc）; strain 312-1 had obvious antimicrobial effect on the six of the plant pathogens except R. solani. [Conclusion] Four strains which had higher antimicrobial effect were obtained and should be further studied for development and application.

Ascitic fluid analysis for diagnosis and monitoring of spontaneous bacterial peritonitis

Polymorphonuclear (PMN) cell count in the ascitic fluid is essential for the diagnosis and management of spontaneous bacterial peritonitis (SBP). To date, PMN cell count is routinely performed by traditional manual counting. However, this method is time-consuming, costly, and not always timely available. Therefore, considerable efforts have been made in recent years to develop an alternative test for a more rapid diagnosis and monitoring of SBP. The use of urinary reagent strips was proposed to achieve an "instant" bedside diagnosis of SBP. A series of reports evaluated the urine strip test for SBP diagnosis and reported promising results. However, a recent large multicenter study revealed a surprising lack of diagnostic effi cacy of the urine screening test for SBP diagnosis. Another method, more recently proposed as an alternative to the manual PMN count, is the measurement of lactoferrin in ascitic fluid, but the data available on the diagnostic value of this test are limited to a single study. However, both urinary reagent strips and ascitic lactoferrin tests are qualitative methods and need, therefore, to be further confirmed by standard cytology of the ascitic fluid. To date, the only quantitative method proposed as a valid alternative to manual PMN counting is automated blood cell counters, commonly used in all laboratories for blood cell counting. Data available in the literature on the diagnostic performance of this method are limited but very promising, and this tool seems to have the potential to replace the manual counting method.

Microbial Community Structure of Casing Soil During Mushroom Growth

The culturable bacterial population and phospholipid fatty acid （PLFA） profile of casing soil were investigated at different mushroom （Agaricus bisporus） cropping stages. The change in soil bacterial PLFAs was always accompanied by a change in the soil eulturable bacterial population in the first flush. Comparatively higher culturable bacterial population and bacterial PLFAs were found in the casing soil at the primordia formation stage of the first flush. There was a significant increase in the ratio of fungal to bacterial PLFAs during mushroom growth. Multivariate analysis of PLFA data demonstrated that the mushroom cropping stage could considerably affect the microbial community structure of the casing soil. The bacterial population increased significantly from casing soil application to the primordia formation stage of the first flush. Casing soil application resulted in an increase in the ratio of gram-negative bacterial PLFAs to gram-positive bacterial PLFAs, suggesting that some gram-negative bacteria might play an important role in mushroom sporophore initiation.

Molecular mechanism of the qnrA genemediated quionlone resistance in Gram-negative bacteria

To explore the prevalence of the plasmid-mediated quinolone resistance gene qnrA in Gramnegative bacteria and to investigate its molecular genetic background and resistance profile in isolates harboring this gene, a total of 629 nalidixic acid-resistant isolates of non-repetitive Gram-negative bacteria were collected from clinical specimens between April 2004 and April 2006 and these isolates were screened for qnrA gene by PCR using specific primers combined with DNA sequencing. The extended spectrum β-1actamase （ESBL） or AmpC-producing isolates were distinguished by the phenotypic confirmatory test combined with DNA sequencing, and the antibiotics susceptibility test for qnrA-positive isolates was carried out by Kirby-Bauer and E-test method. To detect the location of the qnrA gene, plasmid conjugation and Southern hybridization were performed and the integron structure containing the qnrA gene was cloned by PCR strategy and sequenced by primer walking. It was demonstrated that the incidence of the qnrA-positive strains in nalidixic acid-resistant bacteria was 1.9% （12/629）, in which the detection rates for Klebiesiella pneumoniae. Enterobacter cloacae, Enterobacter aerogenes, Citrobacterfreundii and Salmonella choeraesuis were 2.2% （3/138）, 17. 1% （6/35）, 9. 1% （1/11）, 12.5% （1/8）, and 14.3% （1/7）, respectively. The qnrA gene was found to be embedded in the complex sull-type integron located on plasmids with varied size （80-180 kb）. Among them, 4 qnrA-positive isolates carried integron In37 and 8 isolates carried a novel integron, temporarily desig- nated as InX. All the qnrA-positive isolates were ESBL-producing and transferable for the multi-drug resistance. It is concluded that the plasmid-mediated drug-resistance mechanism exists in the quinolone resistant strains of isolates from hospitals in Guangdong area, but the incidence was rather low. Nevertheless, it is still possible that the horizontal transfer of the resistant qnrA gene might lead to the spreading of drug-resistance.

A Novel Halotolerant Bacterium Isolated from El Golea Lake in Algeria and Antimicrobial Potential of this Strain

A halotolerant, gram positive, motile and rod, was isolated from the E1 Gol6a lake of Ghardaia, Alegria and screened for its antimicrobial potential. The strain showed an inhibitory effect to gram positive and gram negative bacteria against Cladosporium spp. and a slight inhibitory effect against C. albicans using chloroform as the extraction solvent and the nutrient broth as production medium. 16S rRNA sequencing showed that the isolate named LMB3981 is a new taxon in the family of Bacillaceae （with 96% similarity）. The strain is close to Filobacillus milosensis and Bacillus haloalkaliphilum with 95% similarity. The phenotypic study showed differences between LMB3981 and two strains that are near and have confirmed the results of 16S rRNA sequencing by specific metabolic properties of the strain.

Novel method for separation and screening of lubricant-degrading microorganisms and bacterial biodegradation

With the rapid increase of lubricant consumption, oil contamination becomes more serious. Biotreatment is an important method to remove oil contamination with some advantages. In this study, acclimatized oil- contaminated soil and used lubricating oil were sampled to isolate lubricant-degrading strains by several methods. 51 isolates were obtained and 24-well plates were employed to assess bacterial potential in high- throughput screening. The method was noted for the prominence of oil-water two-phase system with saving chemicals, shortening cycles and lessening workloads. In order to decrease inaccuracy, subculture and resting cells were inoculated into mineral salt medium with 200 μ1 oil in well plates for the cultivation at 37 ℃ for 5 and 7 days, and the biodegradation potential was characterized by the changes of oil film and cell density. With appropriate evaluation by shaking flask tests, 5 isolates were retained for their potentials with the maxi- mum biodegradation from 1500 to 2200 mg· L-1 and identified as Acidovorax dtrulli, Pseudomonos balearica, Adnetobacterjohnsonii （two isolates with different biodegradation potentials） and Addovorax avenae using 16S rRNA sequencing analysis. Also, lipase activity was determined using indicator titration and p-nitrophenyl palmitate （p-NPP） methods. The results indicated that only p-NPP was successful to test lipase activity with the range of 1.93-6.29 mg· L-1 Although these five strains could degrade 1000 mg· L-1 lubricating oil in 158-168 h, there existed distinct difference in enzyme activity, which demonstrates that lipase activity could not be used as the criterion to evaluate microbial biodegradation potential for petroleum hydrocarbons.

Comprehensive profiling of lysine acetylome in Staphylococcus aureus

The Gram-positive bacterium Staphylococcus aureus(S.aureus)is a wide spread common opportunistic pathogen that causes a wide variety of infectious diseases,from benign skin infections to life-threatening diseases such as the methicillin-resistant Staphylococcus aureus(MRSA)infection.Although emerging evidence suggests that lysine acetylation may play critical roles in bacterial physiology,the atlas of acetylome in S.aureus has not been studied.To comprehensively profile protein lysine acetylation in S.aureus,we used an integrated approach that combined immune affinity peptide enrichment using anti-lysine acetylation antibody,high-pH HPLC fractionation,and HPLC/mass spectrometry analysis.This study led to the identification of 1361 non-redundant acetylation sites on 412 proteins found in a search of S.aureus protein database extracted from the Swiss-Prot database.We further performed bioinformatic analysis to characterize this modification,including gene ontology annotation,protein-protein interaction,and domain analysis of the acetylation sites.We found that the acetylated proteins were enriched in multiple biological pathways,such as ribosomal function and energy metabolism.Our data provides a rich source for functional studies of lysine acetylation in S.aureus.