Abstract A highly efficient aerobic denitrifying strain, designated as T3, was isolated from the sediment of a mariculture tail pond and identified as Photobacterium ganghwense. This is the first reported instance of aerobic denitrification in P. ganghwense. Under electron microscopy, strain T3 measured 1.8–3.0 × 0.9–1.2 μm in size and exhibited a peanut-like shape, typically arranged as single cells. Strain T3 did not exhibit hemolysis on blood agar plates and was sensitive to nearly all tested antibiotics except lincomycin. The strain demonstrated the ability to utilize nitrate for denitrification and could directly assimilate ammonium nitrogen as a nutrient, though it could not utilize nitrite directly. The maximum denitrification rate of 4.15 mg <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11021_2025_8745_Article_IEq1.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="37" /> </InlineMediaObject> <EquationSource Format="TEX">\({\text{NO}}_{3}^{ - }\)</EquationSource>  </InlineEquation>–N/(L h) was achieved when the nitrogen source concentration was 100 mg/L, with nitrate as the nitrogen source, trisodium citrate dihydrate as the carbon source, a C/N ratio of 12.5, pH 7.5, and a temperature of 35°C. High-throughput qPCR chip technology revealed that strain T3 harbors several denitrification-related genes, including narG, napA, nirK2, nirS1, nirS3, nosZ1, and nosZ2; a nitrification-related gene, amoB; an ammonia metabolism gene, ureC; an amino acid metabolism-related gene, gdhA; and an assimilation-related gene, nifH. The presence of napA, nirS, norB, and nosZ genes was further confirmed through PCR and DGGE analyses, indicating that strain T3 possesses a complete denitrification pathway: <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11021_2025_8745_Article_IEq1.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="37" /> </InlineMediaObject> <EquationSource Format="TEX">\({\text{NO}}_{3}^{ - }\)</EquationSource>  </InlineEquation> → <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11021_2025_8745_Article_IEq3.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="37" /> </InlineMediaObject> <EquationSource Format="TEX">\({\text{NO}}_{2}^{ - }\)</EquationSource>  </InlineEquation> → NO → N2O → N2.

Characterization and Complete Denitrification Pathway of Aerobic Denitrifying Photobacterium ganghwense Strain T3 Isolated from a Mariculture Sediment

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发表日期：

2025年11月17日

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L. Y. Li,
J. Li,
Y. Wu,
M. H. Liu,
X. F. Zheng,
B. Wu,
C. X. Zhao,
Z. L. Peng

摘要

Abstract

A highly efficient aerobic denitrifying strain, designated as T3, was isolated from the sediment of a mariculture tail pond and identified as Photobacterium ganghwense. This is the first reported instance of aerobic denitrification in P. ganghwense. Under electron microscopy, strain T3 measured 1.8–3.0 × 0.9–1.2 μm in size and exhibited a peanut-like shape, typically arranged as single cells. Strain T3 did not exhibit hemolysis on blood agar plates and was sensitive to nearly all tested antibiotics except lincomycin. The strain demonstrated the ability to utilize nitrate for denitrification and could directly assimilate ammonium nitrogen as a nutrient, though it could not utilize nitrite directly. The maximum denitrification rate of 4.15 mg \({\text{NO}}_{3}^{ - }\) –N/(L h) was achieved when the nitrogen source concentration was 100 mg/L, with nitrate as the nitrogen source, trisodium citrate dihydrate as the carbon source, a C/N ratio of 12.5, pH 7.5, and a temperature of 35°C. High-throughput qPCR chip technology revealed that strain T3 harbors several denitrification-related genes, including narG, napA, nirK2, nirS1, nirS3, nosZ1, and nosZ2; a nitrification-related gene, amoB; an ammonia metabolism gene, ureC; an amino acid metabolism-related gene, gdhA; and an assimilation-related gene, nifH. The presence of napA, nirS, norB, and nosZ genes was further confirmed through PCR and DGGE analyses, indicating that strain T3 possesses a complete denitrification pathway: \({\text{NO}}_{3}^{ - }\) → \({\text{NO}}_{2}^{ - }\) → NO → N₂O → N₂.