Search Results (3)

The high-altitude lakes are ecological habitats accommodating a vast diversity of microbial populations. These microbes are efficient sources for a variety of enzymes. The objective of this study is to perform in-depth metagenomic profiling of an artificial lake ecosystem located in the Sikkim Himalayan region, deciphering the hydrocarbon degradation potential of this site and mining biocatalysts of industrial importance. In the present study, metagenomic analysis of an artificial Himalayan lake, located in North Sikkim, India, was performed. A comprehensive taxonomic and functional profiling revealed gene mapped to pathways for degradation of hydrocarbons such as toluene, benzoate, ethylbenzene, etc. This site was rich in iron, and the metagenomic investigation revealed genomic signatures of the iron-reducing bacterium; Geothrix fermentans. The appraisal of the carbohydrate metabolic potential of this site divulged the predominance of β-galactosidase genes. The artificial lake metagenome was further compared to publicly available saline and freshwater lakes. At the taxonomic, as well as functional levels, it was found to be closer to freshwater lake metagenome, e.g., Medonta Lake, US, and freshwater Vanda Lake, Antarctica. The microbial community profiling and functional contribution of the artificial Himalayan lake would be beneficial for mining genes encoding various industrially relevant enzymes. Full article

The permanently ice-covered lakes of the McMurdo Dry Valleys, Antarctica are distinctive ecosystems that consist strictly of microbial communities. In this study, water samples were collected from Lake Vanda, a stratified Dry Valley lake whose upper waters (from just below the ice cover to nearly 60 m) are highly oligotrophic, and used to establish enrichment cultures. Six strains of psychrotolerant, heterotrophic bacteria were isolated from lake water samples from a depth of 50 or 55 m. Phylogenetic analyses showed the Lake Vanda strains to be species of Nocardiaceae, Caulobacteraceae, Sphingomonadaceae, and Bradyrhizobiaceae. All Lake Vanda strains grew at temperatures near or below 0 °C, but optimal growth occurred from 18 to 24 °C. Some strains showed significant halotolerance, but no strains required NaCl for growth. The isolates described herein include cold-active species not previously reported from Dry Valley lakes, and their physiological and phylogenetic characterization broadens our understanding of these limnologically unique lakes. Full article

Lake Vanda is a perennially ice-covered, closed-basin lake in the McMurdo Dry Valleys, Antarctica. Laminated photosynthetic microbial mats cover the floor of the lake from below the ice cover to >40 m depth. In recent decades, the water level of Lake Vanda has been rising, creating a “natural experiment” on development of mat communities on newly flooded substrates and the response of deeper mats to declining irradiance. Mats in recently flooded depths accumulate one lamina (~0.3 mm) per year and accrue ~0.18 µg chlorophyll-a cm⁻² y⁻¹. As they increase in thickness, vertical zonation becomes evident, with the upper 2-4 laminae forming an orange-brown zone, rich in myxoxanthophyll and dominated by intertwined Leptolyngbya trichomes. Below this, up to six phycobilin-rich green/pink-pigmented laminae form a subsurface zone, inhabited by Leptolyngbya, Oscillatoria and Phormidium morphotypes. Laminae continued to increase in thickness for several years after burial, and PAM fluorometry indicated photosynthetic potential in all pigmented laminae. At depths that have been submerged for >40 years, mats showed similar internal zonation and formed complex pinnacle structures that were only beginning to appear in shallower mats. Chlorophyll-a did not change over time and these mats appear to represent resource-limited “climax” communities. Acclimation of microbial mats to changing environmental conditions is a slow process, and our data show how legacy effects of past change persist into the modern community structure. Full article