The existence of multiple-antibiotic-resistant strains of environmental bacteria is commonly linked to human activities. However, multiple-antibiotic-resistant strains of bacteria are also widely found in the Antarctic that has limited human activity. This study was conducted to examine the prevalence of antibiotic-resistant strains among Antarctic bacteria. Forty-five bacterial strains from Estrellas lake of King George Island and Crater lake of Deception Island, Antarctic, were exposed to 30 different antibiotics. Forty out of the 45 bacterial strains were affiliated to 12 genera, Aeromicrobium, Arthrobacter, Bacillus, Brevundimonas, Cryobacterium, Dyadobacter, Flavobacterium, Methylibium, Pedobacter, Pseudomonas, Rhodococcus, and Sphingomonas. Among the bacteria, 43 strains were resistant to at least three antibiotics, and 26 strains were resistant to 10 or more different antibiotics. Pseudomonas spp. and four unknown Microbacteriaceae bacteria were found to be resistant to majority of the antibiotics tested. Two bacteria, each from Estrellas and Crater lakes, were sensitive to all the antibiotics tested. These results indicated that Antarctic bacteria are probably the reservoirs for antibiotic resistance genes.

An actinobacterial strain with antimicrobial activity, INACH3013, was isolated from soil collected from Antarctica. The taxonomic status of the isolate was established using a polyphasic approach. The strain was identified as belonging to the genus Streptomyces based on the scanning electron microscopic observation and partial 16S rRNA gene sequence analysis. The sequence analysis revealed that strain INACH3013 is closely related to Streptomyces fildesensis (99.8%), S. beijiangensis (98.1%) and S. purpureus (97.2%). A phylogenetic tree constructed using the partial 16S rRNA gene sequences of strain INACH3013 and closely related strains revealed that INACH3013 fell into the same subclade as S. fildesensis and S. purpureus. Strain INACH3013 was observed to be psychrotolerant, slightly halotolerant (up to 5% NaCl) and capable of inhibiting the growth of seven Gram-negative and eight Gram-positive foodborne pathogens. The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of the strain is KJ624755.

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Glycyrrhizic acid (GA) ameliorates many components of the metabolic syndrome, but its potential therapeutic use is marred by edema caused by inhibition of renal 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2). We assessed whether 100 mg/kg per day GA administered orally could promote metabolic benefits without causing edema in rats fed on a high-sucrose diet. Groups of eight male rats were fed on one of three diets for 28 days: normal diet, a high-sucrose diet, or a high-sucrose diet supplemented with GA. Rats were then culled and renal 11β-HSD2 activity, as well as serum sodium, potassium, angiotensin II and leptin levels were determined. Histological analyses were performed to assess changes in adipocyte size in visceral and subcutaneous depots, as well as hepatic and renal tissue morphology. This dosing paradigm of GA attenuated the increases in serum leptin levels and visceral, but not subcutaneous adipocyte size caused by the high-sucrose diet. Although GA decreased renal 11β-HSD2 activity, it did not affect serum electrolyte or angiotensin II levels, indicating no onset of edema. Furthermore, there were no apparent morphological changes in the liver or kidney, indicating no toxicity. In conclusion, it is possible to reap metabolic benefits of GA without edema using the current dosage and treatment time.

King George Island (KGI) and Deception Island (DCI) are members of the South Shetland Islands in Antarctica, each with their own landscape and local environmental factors. Both sites are suitable for longterm monitoring of bacterial diversity shift due to warming, as temperature rises relatively faster than East Antarctica. This study was conducted to determine and compare the baseline diversity of soil bacteria in KGI and DCI. 16S rDNA amplicons of bacteria from both sites were sequenced using Illumina next generation sequencer. Results showed that major phyla in KGI and DCI were Actinobacteria, Proteobacteria, Chloroflexi, Verrucomicrobia, Bacteriodetes and Acidobacteria. The distribution and evenness of the soil bacterial communities varied at genus level. The genera Sphingomonas sp. was predominant at both sites while the subsequent six major genera differed. Two bacterial genera, Legionella and Clostridium were also found in low abundance in both sites, both of which may contain pathogenic members. Further verification will be required to determine whether the pathogenic members of these genera are present in both sites.

The draft genome sequence of Streptomyces fildesensis strain INACH3013, a psychrotrophic bacterium isolated from Northwest Antarctic soil, was reported. The genome sequence totaling 9,306,785 bp resulted from 122 contigs characterized by a GC content of 70.55%.