Phylogenetic Analysis and Clade Representation of Publicly Available nosZ Genes Relevant to Wastewater Denitrification

کد مقاله : 1103-IWWA

نویسندگان

Bahareh Karimi Douna *1، Ashraf Sadat Hatamian Zaremi2 1دانشگاه تهران 2University of Tehran

چکیده مقاله

Biological denitrification governs nitrogen removal and nitrous oxide (N2O) mitigation in wastewater treatment systems. The terminal step, reduction of N2O to dinitrogen, is catalyzed by nitrous oxide reductase, encoded by nosZ, which forms two phylogenetically distinct clades, Clade I and Clade II. This study characterized wastewater-relevant nosZ diversity using a reproducible workflow. Of 50 nucleotide sequences retrieved from NCBI, 2 were excluded for not meeting a predefined environmental/wastewater relevance criterion, yielding 48 curated, non-redundant sequences (26 genera; length 1,878-1,989 bp; GC 38.4-66.8%). All 48 returned a significant, non-self BLASTN match at approximately 100% query coverage (mean identity 98.6%, median 99.8%; 5 sequences below 95%, all to congeneric or conspecific relatives) and a significant conserved-domain hit at the protein level. Neighbor-Joining (two distance models) and Maximum Likelihood, each with 1,000 bootstrap replicates, separated 46 Proteobacterial Clade-I sequences from a Clade-II pair (Schinkia azotoformans and Sphingobacterium siyangense; n=2, interpreted with caution). Adding a literature-confirmed Clade II reference (Geobacillus thermodenitrificans; Sanford et al., 2012) placed it within this pair at 90.8-99.7% bootstrap support across methods, supporting the clade assignment beyond phylum-level inference. Four of 10 multi-sequence genera were consistently monophyletic across all reconstructions, while a fifth, Stutzerimonas, showed weak, method-dependent monophyly. As a secondary finding, Schinkia azotoformans showed the greatest apparent sequence divergence in the dataset. These results show that curated public sequence data can recapitulate the major phylogenetic separation between nosZ-I- and nosZ-II-associated sequences and provide an accessible framework for future studies of N2O-reducing wastewater communities.

کلیدواژه ها

: nosZ, denitrification, wastewater treatment, NCBI, phylogenetic analysis, bioinformatics

وضعیت: پذیرفته شده برای ارسال فایل های ارائه پوستر