engleski

Nitrifier diversity in geothermal springs - who likes it hot?

Microbial communities in geothermal waters are composed of various, phylogenetically diverse microorganisms adapted to life under extreme conditions such as temperature and pH. Many previous studies have established that the abundance and diversity of microorganisms are usually reduced when compared to other aquatic habitats [1]. The primary objective was to identify, enrich and characterize nitrifying microorganisms (ammonia and nitrite oxidizing, and comammox microorganisms) from Croatian geothermal springs and wells. We used amoA gene quantitative PCR to quantify ammonia oxidizer communities in geothermal samples, and thereafter select localities for nitrifier enrichment experiments. One spring (Antunovo vrelo) and two wells (TS Stubicke and Krecaves) have been selected for sample collection, and enrichment experiments. AOA of the genera Candidatus Nitrosotenuis and Candidatus Nitrososphaera as well as comammox Nitrospira were detected to occur at high abundance in the selected samples, based on 16S rRNA gene amplicon sequencing and amoA gene qPCR data. However, enrichment procedures showed only limited success in respect to AOA enrichment, while comammox Nitrospira did seem to prevail and grow in a fraction of enrichment cultures. Interestingly, ammonia oxidation also occurred in enrichments in which amoA gene qPCR consistently yielded negative results, indicating a enrichment of novel, hitherto unknown ammonia oxidizers. Further exploration of the enrichment cultures by metagenome sequencing is underway.

hot springs ; nitrogen cycle ; enrichment, cultivation ; qPCR

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