Psychrotolerant Sphingobacterium kitahiroshimense LT-2 Isolated from Dhundi Glacier, Himachal Pradesh: Origin Prediction and Future Application
A psychrotolerant bacterium, isolated from Dhundi Glacier, Himachal Pradesh (India) was identified as Sphingobacterium kitahiroshimense LT-2 on the basis of biochemical, molecular and phylogenetic analysis. Sphingobacterium kitahiroshimense was first reported from Japan and was isolated from the city of Kitahiroshima, Hokkaido, Japan. In this report we have discussed about the origin of our strain and predicted that air masses and dust associated microbial cells transportation phenomena may be applicable for the origin of this species in this region. Enzymes and secondary metabolites secreted by the genus Sphingobacterium have enormous potentiality regarding their biotechnological application. Preliminary study of our strain based on metabolic profiling through HPLC showed many new metabolites were secreted by the bacterium when grown in presence of different sugar medium at 28 °C. As far as our knowledge this is the first report about Sphingobacterium species isolated from this region. This preliminary finding will help to draw an idea about the bacterial population in this Himalayan Glaciers (in HP) as well as biotechnological application of this strain can be explored further.
KeywordsPsychrophiles Psychrotolerant bacteria Sphingobacterium Secondary metabolites Cold active enzymes Dust associated microbial cells transportation
The organisms thriving in extreme ecosystems have prosperous resource of various chemical and novel natural products with interesting bioactivities. Among them, psychrophiles which can be found in Arctic, Antarctic and Himalaya are “cold-loving” microorganisms living at sub-zero temperatures undergo certain adaptations by using variety of mechanisms to sustain their cell cycle . These include the production of cold-shock and anti freeze proteins, synthesis of cold tolerant enzymes for the regulation of metabolic pathways, alterations in membrane composition to increase membrane flexibility, ample translation and proper protein folding under cold conditions. These adaptations are often accompanied by certain unique modifications to both gene regulation and metabolic pathways, increasing the possibility of finding unique functional metabolites of pharmaceutical importance . The micro organisms dwelling in the cold habitat are also found to be the rich source of secondary metabolites which mainly showed antibacterial and free radical properties. The psychrophilic microorganisms are of two types viz. Stenopyschrophiles (true psychrophiles) that grow at definite low range of temperature (0–15 °C) and cannot grow at higher temperature range and Eupsychrophiles (psychrotolerant or psychrotrophs) which can grow at low temperature conditions and can tolerate up to mesophilic temperature range (20–25 °C) . Very little study has been done till date on the bacterial diversity of the Himalayan glaciers whereas this region is considered as a place of one of the most underutilized resources. The psychrophilic and psychrotolerant cultivable bacterial strains are dominant in the Himalayan ecosystem. Approximately 45% of cultivable bacterial strains from this region belonged to the Proteobacteria group in which γ-Proteobacteria and β-Proteobacteria constitutes up to 39 and 31% respectively. The second most predominant class is Firmicutes (32%) followed by Actinobacteria (16%) and Bacteroidetes (6%). The most abundant strains of microorganisms in Himalayan range belonged to the genus Bacillus (30%) followed by Pseudomonas (24%) and Arthrobacter (12%) .
The family Sphingobacteriaceae comprises of certain psychrotolerant microorganisms such as members of genus Sphingobacterium in which cells comprises of high concentration of sphingophospholipids which helps the microorganisms to adapt in cold conditions . The first discovery of this genus Sphingobacterium was proposed by Yabuuchi et al. . The family members of this genus have been isolated from different sources and up to 32 species of Sphingobacterium have been identified . The main fatty acid composition of Sphingobacterium comprises of iso-C15:0, iso-C15:0 2-OH, C16:1ω7c and C17:0 3-OH and biochemical characteristics includes catalase and oxidase positive and negative for gelatinase and indole production .
As far as our knowledge this is the first report about Sphingobacterium species isolated from this region. The findings from this preliminary study are important in a sense that it can give valuable idea about the bacterial population in Himalayan Glaciers (HP) as well as the bacterium isolated from this study can be utilised further for biotechnological application.
Financial support for this work was provided by SERB-DST, Govt. of India (PDF/2016/000818). We are thankful to Ms. Riju Parmar and Dr. Anurag Linda for their help in strain collection. We gratefully acknowledged IMTECH, Chandigarh for their support regarding the identification of the strain.
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Conflict of interest
Authors declare no conflict of interest.
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