Ioana Mereuta
The University of Bucharest
Title: Microbial community specialization following kerosene pollution
Submitted Date: 21-04-2016
Biography
Ioana Mereuță is a first year PhD student at the University of Bucharest, Department of Genetics. Her main interests target the field of microbial ecology, studies on microbial communities involved in biodegradation processes, metagenomic approach, key genes and enzimes, as well as isolation and identification of microbial strains with highly specialized enzimatic equipment.
Abstract
A major part of anthropogenic activities have as consequence release of petroleum and its derivates into various ecosystems. Thus, endogenous microbial communities facing such pollutants show highly versatile adaptation capacity, being able to survive in most any new environmental condition. This study analyses for 80 days, the structural and metabolic shift of a soil microbial community following kerosene pollution. Metabolic profiles of the community at given time points were obtained using Biolog Ecoplates System, for utilization of 31 different carbon sources. Data from each plate was normalized by the average well color development (AWCD). Statistical analysis implied guild grouping and one-dimensional relative divergence metric. Structural studies addressed molecular level using Ribosomal Intergenic Spacer Analysis (RISA). Data analysis was performed on OTUs (Operational Taxonomic Units) on ITS (Internal transcribed spacer) phylotype. The highly complex 31-dimensions data was compressed into 5 dimensions, and the total carbon source utilization percentage was divided in 5 guilds accordingly. Shifts in the % of carbon utilization for the 5 groups, in time, following pollution implied significant functional changes in the microbial community. Functional divergence expressed as Euclidean distance confirmed the drastic metabolic shift from the initial point. Moreover, the number of OTUs preceding pollution drastically decreased, thus suggesting a high taxonomical specialization within the microbial community. This study reveals an endogenous microbial community shift of the metabolic activities, confirmed also as a structural specialization, as an expression of the high adaptation potential of the microbial communities to new environmental conditions.
Ekaterina Koltsova
Lomonosov Moscow State University, Russia
Title: Application of Physiological and Biochemical Methods
Submitted Date: 13-05-2016
Biography
Ekaterina Koltsova has completed Master Degree from Lomonosov Moscow State University in 2013 and now is proceeding PhD studies. Alena Tyapkina has completed Master Degree from Lomonosov Moscow State University in 2014.Natalia Manucharova is a professor of Lomonosov Moscow State University since 2015 (Faculty of Soil Science, Department of Soil Biology), PhD in Biological Sciences since 2012. She published over 100 articles in the area of soil microbiology.rnThe study was supported by the RFBR grant 15-29-02499rn
Abstract
Aim: The comparative analysis of the functional activity and composition of hydrolytic microbial complexes of modern and buried chestnut soils and buried permafrost soils.
Materials and methods: Subjects of the study were the buried subkurgan paleosoils (deposition depth 0.5 and 2.5 m, burial age 3500 and 4500 years respectively), modern chestnut soils and buried permafrost marine terrace sediments (deposition depth 9 m). The structure of the hydrolytic microbial complex was determined by the microcosm method with initiation of microbial succession by humidification and introduction of purified polysaccharides: chitin (ICN Biomedicals, Germany) and pectin (Sigma, Germany) at concentrations of 0.2%. Soil humidified with water (1 mL/5 g soil) without a substrate was used as a control. Bacterial cell numbers, mycelium length, and biomass of actinomycetes and fungi were determined by the fluorescence microscopy (Axioskop 2 plus, Zeiss, Germany) on days 0, 3, and 10. Diversity and abundance of metabolically active cells representing individual phylogenetic groups were determined using fluorescence in situ hybridization (FISH).
Main results: The absolute values of biomass in the control soil samples had a gradual decrease of the values with increasing age and depth of deposition of the samples, while the samples of buried soils and buried permafrost sediments responded much better to introduction of substrates (biomass increased 5–7 fold if compared to control) than the samples of modern soils. The fraction of cells identified as metabolically active was comparable in all soil samples (30–40% of the total cell number), except permafrost samples (10%). The rate of increase of the share of active microorganisms in both samples of buried soil and sediments was much higher than in the modern soils and the intensity of response correlated with the age and deposition depth of the sample.
Conclusion: Absolute values of total and active biomass gradually decreased with the increase of deposition depth and age of the soil, but the intensity of response to the introduction of the substrate increased with the deposition depth and age of the soil. Supposedly it is due to the fact that the organic substance income to subsurface microbiomes is low and there occurs the selection of species, which are able to hydrolise complex substrates and are capable of fast growth and multiplication.
