This research was conducted to analyze drinking water quality of Kathmandu valley. Total 969 water samples (392 from dug wells, 287 from deep boring, 218 from treated water, 46 from tap and 26 from other water sources) received from different places of Kathmandu, Lalitpur and Bhaktapur districts during March 2012 to March 2013. These samples were analyzed for the determination of physical (pH, temperature, conductivity, turbidity), chemical (hardness, chloride, iron, arsenic, ammonia, nitrate) and microbiological (total Coliform) parameters. It was found that the temperature and nitrate were within the WHO standards while pH, conductivity, turbidity, chloride, iron, arsenic, ammonia, and Coliform bacteria exceeded the WHO standard guideline. In ground water ( well and Boring), pH, conductivity, hardness, turbidity, iron, arsenic, chloride, ammonia and total Coliform count crossed WHO standards as 5%, 2%, 0.8%, 36%, 51%, 0.1%, 2%, 11% and 86 % respectively. Hardness was within the standard in both  reated and tap water samples. Compared to treated water, pH, arsenic and chloride were within the standard in tap water. The common problematic parameters of different sources of drinking were turbidity, iron, ammonia and conductivity. Coliform bacteria were found in 36% samples of treated water whereas 80% tap water samples were contaminated from Coliform bacteria.DOI: http://dx.doi.org/10.3126/njst.v15i1.12027Nepal Journal of Science and TechnologyVol. 15, No.1 (2014) 115-120

Acid lime (Citrus aurantifolia) is an important commercial fruits crop, cultivated in terai to high hills of Nepal. High variation of acid lime fruits are observed in existing landraces due to crossing within the other citrus species. Determination of genetic variation is important to the plant breeders for development of high yielding variety and hybrids. Therefore, an attempt has been made to study the genetic diversity of 62 acid lime landraces, collected from different altitudinal range in the eastern part of Nepal, using SSR markers. Twelve Simple Sequence Repeat (SSR) primer pairs were used to assess the genetic diversity of acid lime. The average genetic similarity level among the 62 accessions was 0.77, ranging from 0.54 to 1.0 and separated five major cluster groups. Total of 33 alleles were detected by eleven primer pairs and size of alleles ranged from 50 to 225. Average polymorphic information content (PIC) value was 0.50, whereas highest 0.75 and lowest 0.18 was observed in CAT01 and GT03 loci respectively. The results of the study clearly indicated that, SSR markers are highly polymorphic and more informative for the assessment of genetic diversity of acid lime landraces.

Acid lime (Citrus aurantifolia Swingle) is an important commercial fruit crop, cultivated from terai to high hill landscapes of Nepal. However, production and productivity is very low due to various reasons including infestations by various diseases and pests, lack of diseases and pests resistant and high yielding varieties. In this context, determination of genetic variation at molecular level is fundamental to citrus breeders for the development of elite cultivars with desirable traits. In the present study, Random Amplified Polymorphic DNA (RAPD) marker technique has been employed to assess genetic diversity in 60 acid lime landraces representing different agro-ecological zones of eastern Nepal. Nine selected arbitrary primers generated 79 RAPD fragments of which 75 were polymorphic (94.94%). Phenogram was constructed by NTSYS-PC ver. 2.21i using UPGMA cluster analysis based on Jaccard's similarity coefficient to deduce overall genetic diversity and relationships of the acidlime genotypes under study. Sixty acid lime landraces formed seven clusters and similarity value ranged from 38% to 98% with an average of 72%. Genetic variation at different agro-ecological zones was assessed using Popgene ver. 1.32 and found 47% to 69.6% polymorphism. Shannon's index and Nei's gene diversity showed highest level of acid lime diversity in Terai zone (PPB, 69.62%; H, 0.213; I, 0.325) followed by mid-hill zone (PPB, 67.09%; H, 0.208; I, 0.317). The results obtained will be useful to citrus breeders for elite cultivar development. The RAPD-PCR technique is found to be the rapid and effective tool for genetic diversity assessment in acid lime landraces of Nepal.

Pectinase enzymes are one of the commercially important enzymes having great potential in various industries especially in food industry. Pectinases accounts for 25 % of global food enzymes produced and their market is increasing day by day. Therefore, the exploration of microorganism with novel characteristics has always been the focus of the research. Microorganism dwelling in unique habitat may possess unique characteristics. As such, a pectinase producing fungus Aspergillus niger strain MCAS2 was isolated from soil of Manaslu Conservation Area (MCA), Gorkha, Nepal. The optimum production of pectinase enzyme was observed at 48 h of fermentation. The pectinase enzyme was partially purified by cold acetone treatment followed by Sephadex G-75 gel filtration chromatography. The partially purified enzyme exhibited maximum activity 60 U/mg which was almost 8.5-fold higher than the crude pectinase. The approximate molecular weight of the enzyme was found to be 66 kDa as observed from SDS-PAGE. The pectinase enzyme was active at broad range of temperature (30–70 °C) and pH (6.2–9.2). Optimum temperature and pH of the pectinase enzyme were 50 °C and 8.2 respectively. The enzyme was stable up to 70 °C and about 82 % of pectinase activity was still observed at 100 °C. The thermostable and alkaline nature of this pectinase can meet the demand of various industrial processes like paper and pulp industry, in textile industry, fruit juice industry, plant tissue maceration and wastewater treatment. In addition, the effect of different metal ions on pectinase activity was also studied.

Objectives: In order to evaluate the quality assurance of drinking water in Kathmandu valley, this study analyzed selected physiochemical and microbial parameters of treated water samples and compared with Nepal Drinking Water Quality Standards (NDWQS). Methods: Treated water samples were collected from all over the Kathmandu valley and analyzed in terms of physicochemical and microbiological parameters over the period of one year from July 2017 to July 2018. The physio-chemical parameters of water samples were performed according to standard methods for the examination of water and wastewater. The total coliforms were enumerated by standard membrane filtration technique. Results: We report that microbiological aspect of treated water was the major problem as 66% of the water samples crossed the guideline value for total coliform count. Above 92% of jar water samples, 77% of tanker water samples and 69% of filtered water samples had the total coliform count exceeding the NDWQS. Moreover, 20% of bottled water was contaminated by coliform bacteria. Iron and ammonia content were found to be higher than the guideline values in 16% and 21% of the total treated water samples respectively. Analyzing the types of treated water samples showed that 35% and 15% of tanker water samples had higher ammonia and iron content respectively, and the same parameters were higher in 23% and 19% in the filtered water samples respectively than the standard criteria recommended by NDWQS. Conclusion: The treated water samples exceed the standard values set by NDWQS and hence had poor quality. The presence of faecal pollution indicating coliform bacteria was the key problem for treated drinking water of Kathmandu valley. Therefore, monitoring and proper treatment of water should be conducted to prevent dissemination of waterborne diseases.