Diversity and physiology of culturable bacteria associated with a coastal Antarctic ice core

Abstract

Microbiological studies of polar ice at different depths may provide important comparisons, as they preserve records of microbial cells and past climate. In this study, we examined bacterial abundance, diversity and glaciochemical composition from three depths of an ice core from coastal Dronning Maud Land, East Antarctica. Higher bacterial abundance corresponded with high in situ sea-salt Na(+) and dust concentration, suggesting that bacteria might have been transported and deposited into ice along with dust particles and marine aerosols. Fourteen bacterial isolates belonging to the genera Methylobacterium, Brevundimonas, Paenibacillus, Bacillus and Micrococcus were retrieved. Frequent isolation of similar bacterial genera from different cold environments suggests that they possess features that enable survival and metabolism for extended periods of time at sub-zero temperatures. The highest number and diversity of recoverable bacteria was obtained from 49 m depth corresponding to 1926 AD and consisted of bacteria from 4 different genera whereas at 11 m (1989 AD) and 33 m (1953 AD) samples only species belonging to the genera Bacillus was recovered. Among the Bacillus species, Bacillus aryabhattai which has been reported only from the upper stratosphere, was isolated and is the first record from the Earth's surface. Methylobacterium was the most dominant genera at 49 m depth and its prevalence is attributable to a combination of high in situ methanesulfonate concentration, specialized metabolism and environmental hardiness of Methylobacterium. Some of the isolated bacteria were found to respire and grow using methanesulfonate, suggesting that they may utilize this substrate to sustain growth in ice. In addition, NO(3)(-) (2.93-3.69 μM), NH(4)(+) (1.45-3.90 μM) and PO(4)(3-) (0.01-0.75 μM) present in the ice could be potential sources fueling bacterial metabolism in this environment. It could be deduced from the study that variation in bacterial abundance and diversity was probably associated with the prevailing in situ conditions in ice.

Phylogenetic analysis and biological characteristic tests of marine bacteria isolated from Southern Ocean (Indian sector) water

“…In the present study, isolates were producing extracellular enzymes such as esterase, protease, urease, amylase, etc. Similar study was done by Antony et al (2012), showed that bacteria isolated from Antarctic ice core region are also producing cold adaptive enzymes. These extracellular or cold-adaptive enzymes can be an important source of new catalysts possessing useful enzymological characteristics, e.g., Candida antarctica produces lipase A and B.…”

“…Isolates were screened for starch hydrolysis, in ABM containing 1% soluble starch (Antony et al, 2012). After the proper growth, the plates were flooded with Gram's iodine and appearance of clear zone around the colony was taken as positive result.…”

Bacterial Diversity in Deep-Sea Sediments from Afanasy Nikitin Seamount, Equatorial Indian Ocean

“…Recently, bacterial abundance, diversity and glaciochemical composition from three depths, corresponding to 1926 AD, 1989 AD and 1953 AD, from an ice core of coastal Dronning Maud Land, East Antarctica have been analyzed (Antony et al 2012). Further, 14 bacterial isolates belonging to the genera Methylobacterium, Brevundimonas, Paenibacillus, Bacillus and Micrococcus were reported by Antony et al (2012).…”

“…Further, 14 bacterial isolates belonging to the genera Methylobacterium, Brevundimonas, Paenibacillus, Bacillus and Micrococcus were reported by Antony et al (2012). The deep-sea environments of the South Atlantic Ocean were studied for culturable bacteria by Castro da Silva et al (2013), who reported that g-Proteobacteria and Firmicutes were the most frequently cultured with Halomonas the most frequent genus among the strains.…”

Antarctic Palaeoclimate Reconstruction Using Ice Cores: Indian Initiatives during 2008-2016

“…Studies also revealed that the tephra accreted during the Agung (1963) and Krakatau (1883) eruptions harbored microbial cells (both coocoid and rods), suggesting that volcanic ash particles could provide a significant micro-niche for microbes and nanobes in the accreted ice (Laluraj et al, 2009). Microbiological studies of polar ice at different depths of the above ice core also provided an important comparison, as they preserve records of microbial cells and past climate conditions (Antony et al, 2012). The bacteria identified from the different depth of the ice core might have been transported and deposited into ice along with dust particles and marine aerosols.…”