Identification and biological characteristics of Enterococcus casseliflavus TN-47 isolated from Monochamus alternatus.

With the widespread use of antibiotics, the incidence of antibiotic resistance in microorganisms has increased. Monochamus alternatus is a trunk borer of pine trees. This study aimed to investigate the in vitro antimicrobial and biological characteristics of Enterococcus casseliflavus TN-47 (PP411196), isolated from the gastrointestinal tract of M. alternatus in Jilin Province, PR China. Among 13 isolates obtained from the insects, five were preliminarily screened for antimicrobial activity. E. casseliflavus TN-47, which exhibited the strongest antimicrobial activity, was identified. E. casseliflavus TN-47 possessed antimicrobial activity against Staphylococcus aureus USA300 and Salmonella enterica serovar Pullorum ATCC 19945. Furthermore, E. casseliflavus TN-47 was sensitive to tetracyclines, penicillins (ampicillin, carbenicillin, and piperacillin), quinolones and nitrofuran antibiotics, and resistant to certain beta-lactam antibiotics (oxacillin, cefradine and cephalexin), macrolide antibiotics, sulfonamides and aminoglycosides. E. casseliflavus TN-47 could tolerate low pH and pepsin-rich conditions in the stomach and grow in the presence of bile acids. E. casseliflavus TN-47 retained its strong auto-aggregating ability and hydrophobicity. This strain did not exhibit any haemolytic activity. These results indicate that E. casseliflavus TN-47 has potential as a probiotic. This study provides a theoretical foundation for the future applications of E. casseliflavus TN-47 and its secondary metabolites in animal nutrition and feed.

[Phytoplankton community structure in Mingzhu Lake of Chongming Island, Shanghai].

A preliminary study was conducted on the phytoplankton community structure and the annual variation of species diversity in Mingzhu Lake of Chongming Island from January to December 2007. A total of 120 phytoplankton species belonging to 8 phyla and 63 genera were collected, among which, Phormidium tenue, Meismopedia tenuissima, M. convoluta, Microcystis incerta and Synedra ulna were the dominant species. The mean annual density and biomass of the phytoplankton were 5361.57 x 10(4) cell x L(-1) and 7.68 mg x L(-1) respectively. There was a significant difference in the monthly phytoplankton standing crop (P < 0.01) , being the highest in July, but no significant difference was observed among different observation stations. The Shannon index and Margalef index of the phytoplankton community were higher in spring and winter than in the summer and autumn. Biological evaluation indicated that the water quality of Mingzhu Lake was better in spring and winter than in the other two seasons, and canonical correlation analysis (CCA) suggested that the main factors affecting the phytoplankton community were water temperature, followed by total phosphorus, and total nitrogen.

[Structural characteristics of chironomid community and their indicative significance in bioassessment of water quality in Mingzhu Lake of Chongming Island, Shanghai].

The structural characteristics of chironomid (Diptera: Chironomidae) community in Mingzhu Lake of Chongming Island, Shanghai, China were studied from July 2006 to April 2008. A total of eleven chironomid species belonging to 10 genera and 3 subfamilies were collected, among which, Propsilocerus akamusi and Microchironomus sp. were predominant. Based on clustering analysis (CA) and importance value (IV), it was found that the dominant species shifted seasonally, with Microchironomus sp. in spring and summer, Tanypus chinensis in autumn, and P. akamusi in winter. There was a significant seasonal difference in the Shannon-Weaver diversity index (H') of the chironomid community, with the lowest in summer and higher in the other three seasons. The H' was significantly correlated with species richness (S) and evenness (J), and more strongly governed by J. The average density and biomass of the chironomid community were the highest in winter, with a minimum density in autumn and a lower biomass in the other seasons. Among the three dominant species, P. akamusi and Microchironomus sp. had more obvious seasonal fluctuations in their population dynamics than T. chinensis. Based on the bioassessment methods of water quality, e.g., H' and Hilsenhoff biotic index (BI), the Mingzhu Lake was considered to be moderately organically polluted and eutrophicated.

[Community structure of rotifer in Mingzhu Lake of Chongming Island, Shanghai].

A comprehensive survey on the quantitative distribution, community structure, species composition, dominant species, and species diversity of rotifer was conducted in the Mingzhu Lake of Chongming Island, Shanghai in January-December, 2008. There were 27 species of rotifer in the Lake, belonging to 8 families and 11 genera. The dominant species were Polyarthra trigla, Trichocerca pusilla, Brachionus calyciflorus, Brachionus forficula, and Philodina sp. The rotifer had an average annual density of (1505.42 +/- 1304.63) ind x L(-1), and an average annual biomass of (2.012 +/- 2.146) mg x L(-1). The Shannon-Wiener diversity index, evenness index, and richness index of rotifer community in the Lake were relatively low, while the dominance index was rather high, indicating that the community structure of the rotifer was unstable. The E/O value wes 1.61 +/- 1.46 on average, and the Q(B/T) values wes 1.23 +/- 0.84 on average. Water temperature was the main factor affecting the rotifer distribution. Biological assessment of water quality suggested that the Mingzhu Lake was on eutrophication.