Science Vision

96-105

Authors: Ksh. Mirabai Devi and S.K. Mehta

This study aimed to assess the effect of extracts of Lyngbya strain, MZUCC066, prepared in different solvents (methanol-100%, ethanol:water-3:7 and dichloromethane:isopropanol-1:1) against six microorganisms that comprise three chlorophycean algae (Chlorella vulgaris, Scenedesmus quadricauda and Selenastrum capricornatum), one cyanobacterian alga (Anabaena variabilis), and two bacterial strains (Bacillus subtilis, ATCC11774 and Bacillus pumilus, ATCC14884). Among the algal test organisms, the highest inhibition was found in S. quadricauda (70%) by dichloromethane:isopropanol extract of Lyngbya followed by A. variabilis (41%) by the same extract. When tested on bacterial test organisms, the highest inhibition zone diameter of 15.67 mm was found in B. subtilis by dichloromethane:isopropanol extract and followed by 14 mm in B. pumilus by the same extract at 100 µl concentration. Minimum inhibitory concentrations of each extract on all the organisms were varied. The present study suggests that Lyngbya has specific bioactivities against different groups of microorganisms.

115-123

Authors: F. Lalbiakmawia and V. Vanthangliana

Water is one of the most important natural resources highly crucial for our day-to-day life. The main sources of water are surface water and ground water. Erratic and irregular availability of surface water leads to exploration and utilization of ground water for irrigation, industrial and domestic purposes. Therefore, the quality of ground water is equally important as its quantity. The present study utilizes geographical information system (GIS) technique to map the spatial variability of ground water quality. Ground water samples were collected from 188 point sources randomly distributed in Aizawl district, Mizoram. The major water quality parameters namely pH, electrical conductivity (EC), total dissolved solids, total hardness, iron, chloride, nitrate and fluoride have been estimated for all the sampling locations. The spatial variation maps of these ground water quality parameters were generated and utilize as thematic layers. These thematic layers were given ranks based on their relative importance. Different classes within each thematic layer were assigned weightages in numerical rating from 1 to 3 as attribute values in GIS environment. Summation of these attributes values and the corresponding rank values of the thematic layers were utilize to generate the final ground water quality map. This final map shows the different classes of ground water quality within the district which can be utilize to provide a guideline for the suitability of ground water uses.

132-135

Authors: J. L. Pudaite

The objective of this study was to determine the effect of nitrogen and phosphorus on the growth and total chlorophyll content of a freshwater microalgae Scenedesmus sp. Growth behavior under modified Chu-10 medium without nitrogen source showed strong inhibition with growth rate reduced to 72.84% after 96 hour of treatment. There was about 10.24% inhibition of growth when the algae were cultured in a modified Chu-10 medium without phosphorus source. The photosynthetic pigment such as total chlorophyll content decreased at the same extent after 96 hour of culture in modified Chu-10 medium without the nitrogen source but not decreases in the medium without phosphorus source and the inhibition was highest in the medium without the nitrogen source.

145-151

Authors: D.V. Lalhlimpuia, R. Shukla, M. Singh and Lalramliana

The study, for the first time, reports the occurrence of the genus Neonoemacheilus from rivers of Mizoram, namely Langkaih and Tlawng rivers,. The study provides descriptions of N. assamensis giving additional characters other than outlined in the original description, such as, number of unbranched dorsal and anal fin rays; intestine arrangement and numbers of vertebrae.