Microbiological safety of household membrane water filter.

Waterborne pathogens outbreaks are major reasons of diarrhea disease worldwide. Detecting and monitoring emerging waterborne pathogens (EWPs) is important for drinking water microbiological safety. The microbiological safety of household water hollow fiber membrane filter which is the end of drinking water treatment process was studied with heterotrophic plate count (HPC) and real-time PCR method. The effect of the flow rate, idle time and washing fashion were investigated. Among the selected filters from three manufacturers, only the PVDF membrane water filter (Brand B) could achieve a good water purification criteria. Brand A was found a certain degree of EWPs in its effluent. The lowest bacteria-removing efficiency of the PVC membrane water filter was found Brand C. Our study showed that the microorganisms could reach up to 10

Effects of carbon, nitrogen and pH on the growth of Aspergillus parasiticus and aflatoxins production in water.

Mycotoxins are considered as the most hazardous fungal metabolites for human, animals and plant health. Recently, more attention has been paid on the occurrence of this group of fungi in different water sources throughout the globe. In this study, Aspergillus parasiticus ATCC strain was used as representative strain producing aflatoxins in drinking water. This study aimed to investigate the activation of fungi in drinking water and their ability to produce aflatoxins (B1, B2, G1, and G2) in water under different ratios of C:N using different concentrations of total organic carbon (TOC) and total nitrogen (TN). Glucose and ammonium sulphate were used for changing the levels of TOC and TN in the selected water media. Similarly, the effects of different water pH levels from 4.5 to 8.2 on the growth of this group of fungi and aflatoxins production were also investigated. The results indicate that the growth of fungi was highest, at C:N ratio of 1:1 as compared to other selected ratios. Furthermore, the findings indicate that the pH levels 5.5-6.5 showed best growth of fungi as compared to other pH levels. Aflatoxin concentrations were measured in the water samples using HPLC technique, but selected fungi were not able to produce aflatoxins in water at applied concentrations of TOC and TN mimicking the ratios and concentrations present in the natural aquatic environment.

Occurrence and variations of five classes of antibiotic resistance genes along the Jiulong River in southeast China.

Antibiotic resistance genes (ARGs) are emerging microbial hazards threatening human health. Many factors, including urban and agricultural activities and water environment changes, can significantly impact the variations of ARGs. An investigation on the occurrence and variations of ARGs in the Jiulong River was done in this study. The water samples were collected from 16 sites ranging from the upper branch to the river mouth of the Jiulong River, in both low- and high-flow periods. Eleven ARG families were tested and quantified by real-time PCR (SYBR Green) methods, and detection assays were conducted for tetA, tetG, aacC1, strA, ermB, cmlA5, vanA, dfrA1, sulII, blaTEM-1 and blaoxa-1 genes. Results showed that nine ARG families were found, then the swine industry and urban activities, including sewage discharge, might be responsible for the high levels of concentrations and relative abundances of ARGs, and the increase of salinity might decrease the relative abundances of ARGs. In addition, some ARG abundances were significantly correlated to the concentrations of NH4+ and PO4-3, particularly in the high-flow period. The human activities were important sources for ARGs in the Jiulong River, which have already become a threat to the safety of drinking water for the nearby cities.