Tehismärgalade mikroobikoosluse struktuur ja selle seos süsteemi puhastusefektiivsusega

Väitekirja elektrooniline versioon ei sisalda publikatsiooneTehismärgalasid (TM) on viimase poole sajandi jooksul kasutatud reovee puhastumise alternatiivse meetodina konventsionaalsete puhastite kõrval. TM erinevad omadused, sealhulgas filtermaterjali tüüp, tööparameetrid ning samuti taimestiku olemasolu, mõjutavad mikroobikoosluste struktuuri, ruumilist jaotust ja aktiivsust süsteemis. Kuna mikroobsed protsessid on TM reovee puhastusel olulise tähtsusega, aitavad uuringud mikroobiökoloogias laiendada teadmisi mikroobikoosluse kujunemisest ja seostest TM tööparameetritega, võimaldades seeläbi luua stabiilse ja metaboolselt aktiivse mikroobikoosluse jaoks sobiliku TM keskkonna ja selle kaudu tõsta erinevate reoainete puhastamise efektiivsust. Käesoleva doktoritöö eesmärgiks oli uurida eri tüüpi TM mikroobikoosluse arvukust ja struktuuri ning kuidas mikroobikoosluse parameetrid on seotud TM puhastusefektiivsusega ja millised keskkonnafaktorid mõjutavad mikroobikoosluse stabiliseerumist uuritavates süsteemides. Uurimisobjektideks olid kolm eri tüüpi TM, millest kaks olid vastrajatud eksperimentaalset TM ja üks üle 15 aasta kasutuses olnud vabaveeline jõevett puhastav TM kompleks. Saadud tulemused näitasid, et reovee koostis, TM tüüp ja töörežiim mõjutavad bakterikoosluse kujunemist ja struktuuri tehismärgalas. Mikroobikoosluse struktuuri kujunemisel oli näha sarnast ajalist suktsessiooni kahe eksperimentaalse TM vahel. Mikroobikoosluse mitmekesisus tõusis märgatavalt mõlema süsteemi esimese kolme kuu jooksul ja seejärel stabiliseerus, sealhulgas olid algsed muutused mikroobikoosluse kujunemisel suurema varieeruvusega kui pärast stabiliseerumist. Nii mikroobikoosluse mitmekesisus kui ka teatud bakteriperekondade osakaalud olid seotud nende süsteemide puhastusefektiivsustega. Töö tulemused kinnitasid mitmete koosesinevate bakterirühmade mõju nii lämmastiku kui orgaaniliste ühendite eemaldamisele reoveest. Uuritavates TM olid peamisteks lämmastikuärastuse protsessideks autotroofne ja heterotroofne nitrifikatsioon ning denitrifikatsioon ning vähemal määral anaeroobne ammooniumi oksüdeerimine, eelkõige vabaveelises tehismärgalas. Käesoleva doktoritöö tulemuste põhjal saab teha järelduse, et erinevate reoainete parimaks eemaldamiseks tuleks TM konstrueerida ja opereerida meetodil, mis loovad sobiva keskkonna mitmekesise ja kõrge metaboolse aktiivsusega mikroobikoosluse kujunemiseks.Treatment wetlands (TWs) have been used over fifty years for purification of different types of wastewater. Pollutant removal processes in TWs are mostly related to microbiologically mediated reactions. Knowledge of the microbial community dynamics and structure and the relationship with the system properties and operating conditions is therefore crucial for the development and optimization of effective TWs. In this thesis, bacterial community abundance, structure and diversity was evaluated, as well as their relationship with the pollutant removal potential in three different types of TWs: experimental greywater-fed hybrid TW, horizontal subsurface flow filters of an experimental hybrid TW, and riverine surface flow TW complex. The origin of wastewater, treatment wetland type and the hydrologic mode determined bacterial community structure and abundance in the treatment system. Significant variation in bacterial community structure were detected during the experimental TW’s start-up period and the community diversity increased. Overall, a comparable bacterial community successional pattern was identified in those systems. Based on the results, stabilisation of bacterial community in the experimental TW systems took about three months. The diversity of bacterial community and relative abundance of certain bacterial genera were positively linked to system treatment efficiency. Organic matter and nitrogen removal in the studied experimental TWs was performed by several small subsets of tightly interconnected bacterial species. Water regime was an important factor in shaping the structure of bacterial communities in the studied riverine TW soils - the communities in the occasionally flooded areas were more diverse and complex than those of the permanently flooded areas. The results suggest that nitrogen removal pathways in the studied TWs were coupled autotrophic and heterotrophic nitrification and denitrification, and in limited amount via anaerobic ammonium oxidation process with the highest potential in soils and sediments of the riverine TW complex. The main conclusion of the doctoral thesis is that TWs should be designed and operated in a way that supports the development of diverse microbial communities with a high abundance of metabolically active microbes

Differences in microbial community structure and nitrogen cycling in natural and drained tropical peatland soils

Funding Information: This was supported by the Estonian Research Council (grant IUT2-16); and the EU through the European Regional Development Fund through Centre of Excellence EcolChange and the European Social Fund (Doctoral School of Earth Sciences and Ecology). We would like to thank the PhD students participating in the field works.Peer reviewedPublisher PD

Soil Bacterial and Archaeal Communities and Their Potential to Perform N-Cycling Processes in Soils of Boreal Forests Growing on Well-Drained Peat

Funding Information: This study was supported by the Estonian Forest Management Centre, the Estonian Research Council grants PRG548, PRG916, and PRG352, WaterJPI-JC-2018_13 project, and Centres of Excellence Environ and EcolChange.Peer reviewedPublisher PD

The bacterial community structure and functional profile in the heavy metal contaminated paddy soils, surrounding a nonferrous smelter in South Korea

Funding Information: The authors wish to thank the Basic Science Research Program of the National Research Foundation (NRF) under the Ministry of Education, Science and Technology (2015R1A2A1A05001885), South Korea for providing funding support toward the completion of this study. This study was supported partially by the Estonian Ministry of Education and Research (Grant IUT2–16), and by the European Regional Development Fund through the Centre of Excellence EcolChange. We thank Saale Truu for the assistance in computer graphics. Funding Information: National Research Foundation of Korea, Grant/Award Number: 2015R1A2A1A05001885; Estonian Ministry of Education and Research, Grant/ Award Number: IUT2–16; European Region Development Fund Publisher Copyright: © 2018 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. Copyright: Copyright 2018 Elsevier B.V., All rights reserved.Peer reviewedPublisher PD

Dynamics of Bacterial Community Abundance and Structure in Horizontal Subsurface Flow Wetland Mesocosms Treating Municipal Wastewater

Dynamics of bacterial community abundance and structure of a newly established horizontal subsurface flow (HSSF) pilot-scale wetland were studied using high-throughput sequencing and quantitative polymerase chain reaction (PCR) methods. Bacterial community abundance increased rapidly within one month and stabilised thereafter in three replicate HSSF constructed wetland (CW) mesocosms. The most dominant phylum was Proteobacteria, followed by Bacteroidetes in wetland media biofilms and Firmicutes in influent wastewater. CW bacterial community diversity increased over time and was positively related to the wastewater treatment efficiency. Increase in the abundance of total bacteria in the community was accompanied with the abundance of denitrifying bacteria that promoted nitrate and nitrite removal from the wastewater. During the 150-day study period, similar patterns of bacterial community successions were observed in replicate HSSF CW mesocosms. The data indicate that successions in the bacterial community in HSSF CW are shaped by biotic interactions, with a significant contribution made by external abiotic factors such as influent chemical parameters. Network analysis of the bacterial community revealed that organic matter and nitrogen removal in HSSF CW could be, in large part, allocated to a small subset of tightly interconnected bacterial species. The diversity of bacterial community and abundance of denitrifiers were good predictors of the removal efficiency of ammonia, nitrate and total organic C in HSSF CW mesocosms, while the removal of the seven-day biochemical oxygen demand (BOD7) was best predicted by the abundance of a small set of bacterial phylotypes. The results suggest that nitrogen removal in HSSF CW consist of two main pathways. The first is heterotrophic nitrification, which is coupled with aerobic denitrification and mediated by mixotrophic nitrite-oxidizers. The second pathway is anaerobic denitrification, which leads to gaseous intermediates and loss of nitrogen as N2

Dynamics of Bacterial Community Abundance and Structure in Horizontal Subsurface Flow Wetland Mesocosms Treating Municipal Wastewater

Dynamics of bacterial community abundance and structure of a newly established horizontal subsurface flow (HSSF) pilot-scale wetland were studied using high-throughput sequencing and quantitative polymerase chain reaction (PCR) methods. Bacterial community abundance increased rapidly within one month and stabilised thereafter in three replicate HSSF constructed wetland (CW) mesocosms. The most dominant phylum was Proteobacteria, followed by Bacteroidetes in wetland media biofilms and Firmicutes in influent wastewater. CW bacterial community diversity increased over time and was positively related to the wastewater treatment efficiency. Increase in the abundance of total bacteria in the community was accompanied with the abundance of denitrifying bacteria that promoted nitrate and nitrite removal from the wastewater. During the 150-day study period, similar patterns of bacterial community successions were observed in replicate HSSF CW mesocosms. The data indicate that successions in the bacterial community in HSSF CW are shaped by biotic interactions, with a significant contribution made by external abiotic factors such as influent chemical parameters. Network analysis of the bacterial community revealed that organic matter and nitrogen removal in HSSF CW could be, in large part, allocated to a small subset of tightly interconnected bacterial species. The diversity of bacterial community and abundance of denitrifiers were good predictors of the removal efficiency of ammonia, nitrate and total organic C in HSSF CW mesocosms, while the removal of the seven-day biochemical oxygen demand (BOD7) was best predicted by the abundance of a small set of bacterial phylotypes. The results suggest that nitrogen removal in HSSF CW consist of two main pathways. The first is heterotrophic nitrification, which is coupled with aerobic denitrification and mediated by mixotrophic nitrite-oxidizers. The second pathway is anaerobic denitrification, which leads to gaseous intermediates and loss of nitrogen as N2

Data from: The bacterial community structure and functional profile in the heavy metal contaminated paddy soils,surrounding a nonferrous smelter in South Korea

The pollution of agricultural soils by the heavy metals affects the productivity of the land and has an impact on the quality of the surrounding ecosystems. The present study investigated the bacterial community structure in the heavy metal contaminated sites along a smelter and a distantly located paddy field to elucidate the factors that are related to the alterations of the bacterial communities under the conditions of heavy metal pollution. Among the study sites, the bacterial communities in the soil did not show any significant differences in their richness and diversity. The soil bacterial communities at the three study sites were distinct from one another at each site, possessing a distinct set of bacterial phylotypes. Among the study sites, significant changes were observed in the abundances of the bacterial phyla and genera. The variations in the bacterial community structure were mostly related to the general soil properties at the phylum level, while at the finer taxonomic levels, the concentrations of arsenic (As) and lead (Pb) were the significant factors, affecting the community structure. The relative abundances of the genera Desulfatibacillum and Desulfovirga were negatively correlated to the concentrations of As, Pb, and cadmium (Cd) in the soil, while the genus Bacillus was positively correlated to the concentrations of As and Cd. According to the results of the prediction of bacterial community functions, the soil bacterial communities of the heavy metal polluted sites were characterized by the more abundant enzymes, involved in DNA replication and repair, translation, transcription, and the nucleotide metabolism pathways, while the amino acid and lipid metabolism, as well as the biodegradation potential of xenobiotics, were reduced. Our results showed that the adaptation of the bacterial communities to the heavy metal contamination was predominantly attributed to the replacement process, while the changes in community richness were linked to the variations in the soil pH values

Impact of polyols on oral microbiome of Estonian schoolchildren

Background - Oral microbiome has significant impact on both oral and general health. Polyols have been promoted as sugar substitutes in prevention of oral diseases. We aimed to reveal the effect of candies containing erythritol, xylitol or control (sorbitol) on salivary microbiome. Methods - Ninety children (11.3 ± 0.6 years) consumed candies during 3 years. Microbial communities were profiled using Illumina HiSeq 2000 sequencing and real-time PCR. Results - The dominant phyla in saliva were Firmicutes (39.1%), Proteobacteria (26.1%), Bacteroidetes (14.7%), Actinobacteria (12%) and Fusobacteria (6%). The microbiome of erythritol group significantly differed from that of the other groups. Both erythritol and xylitol reduced the number of observed bacterial phylotypes in comparison to the control group. The relative abundance of the genera Veillonella, Streptococcus and Fusobacterium were higher while that of Bergeyella lower after erythritol intervention when comparing with control. The lowest prevalence of caries-related mutans streptococci corresponded with the lowest clinical caries markers in the erythritol group. Conclusions - Daily consumption of erythritol, xylitol or control candies has a specific influence on the salivary microbiome composition in schoolchildren. Erythritol is associated with the lowest prevalence of caries-related mutans streptococci and the lowest levels of clinical caries experience