Heterotrophic nitrification-aerobic denitrification characteristics and antibiotic resistance of two bacterial consortia from Marinomonas and Halomonas with effective nitrogen removal in mariculture wastewater

摘要

Heterotrophic nitrification-aerobic denitrification (HNAD) characteristics and antibiotic resistance of two bacterial consortia, Marinomonas communis & Halomonas titanicae (MCH) and Marinomonas aquimarina & Halomonas titankae (MAH), and their single isolates (MC, MA, and H) were determinated in this study. When cultured in sole and mixed N-source media (NH_4~--N and/or NO_2~---N of 10 mg/L), MCH and MAH exhibited greater efficiency and stability of inorganic-N removal than single isolates, and these strains preferred to remove NH_4~--N by simultaneous HNAD in mixed N-source media. Meanwhile, 45%-70% of NH_4~--N and/or NO_2~- -N was mainly converted to organic nitrogen (15%-25%) and gaseous nitrogen (30%-40%) by these strains, and more inorganic-N was transformed to intracellular-N by MCH and MAH via assimilation instead of gaseous-N production by denitrification. Both isolates and their consortia had the maximal NH_4~--N or NO_2~--N removal efficiency above 95% under the optimum conditions including temperature of 20-30 °C, C/N ratios of 15-20, and sucrose as carbon source. Interestingly, bacterial consortia performed greater nitrogen removal than single isolates under the low temperature of 10 °Cor C/N ratios of 2-5. In real mariculture wastewater, MCH and MAH also showed higher NH_4~--N removal efficiency (65%-68%) and more stable cell quantity (4.2-5.2 × 10~8 CFU/mL) than single strains, due to the interspecific coexistence detected by bacterial quantitation with indirect immunoassay. Additionally, these isolates and consortia had stronger resistances to polypeptides, tetracyclines, sulfonamides, furanes, and mac-rolides than other antibiotics. These findings will be conducive to the applications of HNAD bacteria of Marinomonas and Halomonas on reducing nitrogen pollution in mariculture or other saline environments.