Practical applications of PCR primers in detection of anammox bacteria effectively from different types of samples

Research on anammox (anaerobic ammonium oxidizing) bacteria is important due to their biogeochemical and industrial application significance since the first discovery made over two decades ago. By coupling NH₄⁺ and NO₂^- biochemically to form N₂ gas, anammox bacteria contribute significantly to global marine and terrestrial nitrogen balance (responsible for 50, 9~40, and 4~37% of the nitrogen loss for marine, lakes, and paddy soil) and are also useful in energy-conserving nitrogen removal in wastewater treatment. PCR-based detection and quantification of anammox bacteria are an easy, essential, and widely accessible technique used ubiquitously for studying them in many environmental niches. In this article, we make a summary on practical applications of 16S rRNA and functional gene PCR primers, including hydrazine dehydrogenase (Hzo), nitrite reductase (NirS), hydrazine synthase (Hzs), and cytochrome c biogenesis proteins (Ccs) in detection of them. PCR primer performances in both practical applications and tests in silico are also presented for comparison. For detecting general and specific anammox bacterial groups, selection of appropriate PCR primers for different environmental samples and practical application guidance on choice of appropriate primer pairs for different purposes are also offered. This article provides practical information on selection and application of PCR technique in detection of anammox bacteria from the diverse environments to further promote convenient applications of this technique in research and other purposes.