Genome of a thermophilic bacterium Geobacillus sp. TFV3 from Deception Island, Antarctica

Thermophilic microorganisms have always been an important part of the ecosystem,particularly in a hot environment,as they play a key role in nutrient recycling at high temperatures where most microorganisms cannot cope.While most of the thermophiles are archaea,thermophiles can also be found among some species of bacteria.These bacteria are very useful in the fundamental study of heat adaptation,and they are also important as potential sources of thermostable enzymes and metabolites.Recently,we have isolated a Gram-positive thermophilic bacterium,Geobacillus sp.TFV3 from a volcanic soil sample from Deception Island,Antarctica.This project was undertaken to analyze the genes of this thermophilic Antarctic bacterium and to determine the presence of thermal-stress adaptation proteins in its genome.The genome of Geobacillus sp.TFV3 was first purified,sequenced,assembled,and annotated.The complete genome was found to harbor genes encoding for useful thermal-stress adaptation proteins.The majority of these proteins were categorized under the family of molecular chaperone and heat shock protein.This genomic information could eventually provide insights on how the bacterium adapts itself towards high growth temperatures.

Barrientosiimonas humi ethyl acetate extract exerts cytotoxicity against MCF-7 and MDA-MB-231 cells via induction of apoptosis and cell cycle arrest

Objective:To elucidate the cytotoxic effect of the secondary metabolites of Barrientosiimonas humi(B.humi)onMCF-7and MDA-MB-231 human breast cancer cells and itsunderlying mechanisms of action.Methods:The extract was obtained from the fermentation of B.humi and fractionation of the crude extract was conducted via column chromatography.Cytotoxicity of theB.humi extract was determined by using MTT assay and real-time cellular analysis.Morphological changes,cell cycle profiles,mode of cell death,and caspase expressions of control and treated breast cancer cells were determined.Results:The ethyl acetate extract isolated from B.humi was cytotoxicagainst MCF-7 and MDA-MB-231celllines.Oneof thedichloromethane(DCM)fractions,designatedasDCM-F2,exhibited the strongest activity among all the fractions and thereby was selected for further studies.DCM-F2 had selective cytotoxicity on target cells by inducing apoptosis,particularly in the early stage,and cell cycle arrest.Treated cells caused inhibition of cell cycle progression at 72 h leading to a significant increase(P<0.05)in the G0/G1 population.DCM-F2 treated MDA-MB-231 cells showed caspase-dependent apoptosis,whereas DCM-F2 treated MCF-7 cells showed a caspase-independent apoptosis pathway.Five compounds were successfully isolated from B.humi.Cyclo(Pro-Tyr)was the most cytotoxic and selective compound against MCF-7 cells.Conclusions:B.humi ethyl acetate extract exhibits significant cytotoxicity against MCF-7 and MDA-MB-231 cells via induction of apoptosis and cell cycle arrest.