[Effects of nitrogen addition on red soil microbes in the Cinnamomum camphora plantation].

In order to investigate the effects of nitrogen addition on the red soil microbial communities in Cinnamomum camphora plantation, three treatments of nitrogen addition were designated as control (N0: 0 g x m(-2)), low nitrogen (N1: 5 g x m(-2)) and high nitrogen (N2 :15 g x m(-2)). Soil microbial numbers, microbial biomass carbon (C), biomass N and microbial community functional diversity were analyzed using the methods of plate counting, chloroform fumigation and BIOLOG system, respectively. The results showed that the numbers of bacteria in N1 and N2 were significantly higher than the control 1 month after nitrogen addition, but significantly lower than the control 13 months after nitrogen addition, and the number of fungi and actinomycetes were not significantly changed after nitrogen addition. The soil microbial biomass C, N increased with the increase of nitrogen at 1 month, but the soil microbial biomass C increased significantly 13 months after nitrogen addition when compared with 1 month after nitrogen addition. The soil microbial biomass N was lower 13 months after nitrogen addition when compared with 1 month after nitrogen addition, but the difference was not significant (P > 0.05). The variation of the carbon utilization efficiency of soil microbial communities was resulted from the nitrogen addition. The indices of Shannon index, Simpson index and McIntosh index were calculated to show the differences in nitrogen treatments and in times, which turned out to be insignificant.

The high prevalence of Legionella pneumophila contamination in hospital potable water systems in Taiwan: implications for hospital infection control in Asia.

BACKGROUND: The major sources of Legionnaires' disease (LD) are the potable water systems of large buildings including hospitals, nursing homes, and hotels. Culturing the hospital water system for Legionella allows a preventive approach for hospital-acquired LD. However, hospital-acquired LD is rarely reported in Taiwan, and environmental cultures of Legionella in hospital water systems in Taiwan have never been systematically performed. OBJECTIVE: The objective of this study was to determine if Legionella is present in hospital water systems in Taiwan. Water quality analysis was also performed to determine if geographic differences in water quality result in different Legionella positivity rates. METHOD: The water systems of 16 hospitals throughout Taiwan were tested for Legionella by culture. Standardized culture procedures were followed. RESULTS: Legionella pneumophila was isolated from 63% (10/16) of the hospital water systems; 19% (3/16) of the hospitals had an L. pneumophila positive rate greater than 30%. L. pneumophila serogroups 1 and 6 (strains that are most responsible for Legionella infections) were isolated from 80% (8/10) and 60% (6/10), respectively, of the hospitals that yielded L. pneumophila in their water distribution systems. CONCLUSION: As was shown in epidemiological studies in the USA and Spain, hospital-acquired legionellosis may be prevalent but underdiagnosed in Taiwan.