Civiero Enrico, Pintus Manuela, Ruggeri Claudio, Tamburini Elena, Sollai Francesca, Sanjust Enrico, Zucca Paolo
Dipartimento di Scienze Biomediche, Università degli Studi di Cagliari, SP 1 Km 0,700, 09042 Monserrato (CA), Italy.
Biology (Basel). 2018 Jun 30;7(3):39. doi: 10.3390/biology7030039.
Agriculture and intensive farming methods are the greatest cause of nitrogen pollution. In particular, nitrification (the conversion of ammonia to nitrate) plays a role in global climate changes, affecting the bio-availability of nitrogen in soil and contributing to eutrophication. In this paper, the DSBCA06 was investigated for growth kinetics on nitrite, nitrate, or ammonia as the sole nitrogen sources (10 mM). Complete nitrite removal was observed in 48 h up to 10 mM initial nitrite. Nitrogen was almost completely assimilated as organic matter (up to 90% using higher nitrite concentrations). The strain tolerates and efficiently assimilates nitrite at concentrations (up to 20 mM) higher than those previously reported in literature for other yeasts. The best growth conditions (50 mM buffer potassium phosphate pH 7, 20 g/L glucose as the sole carbon source, and 10 mM nitrite) were determined. In the perspective of applications in inorganic nitrogen removal, other metabolic features relevant for process optimization were also evaluated, including renewable sources and heavy metal tolerance. Molasses, corn, and soybean oils were good substrates, and cadmium and lead were well tolerated. Scale-up tests also revealed promising features for large-scale applications. Overall, presented results suggest applicability of nitrogen assimilation by DSBCA06 as an innovative tool for bioremediation and treatment of wastewater effluents.
农业和集约化养殖方式是氮污染的最大成因。特别是硝化作用（氨转化为硝酸盐）在全球气候变化中发挥作用，影响土壤中氮的生物有效性并导致富营养化。本文研究了DSBCA06在以亚硝酸盐、硝酸盐或氨作为唯一氮源（10 mM）时的生长动力学。在48小时内观察到初始浓度达10 mM的亚硝酸盐被完全去除。氮几乎完全被同化为有机物（使用较高亚硝酸盐浓度时可达90%）。该菌株能够耐受并有效同化浓度高达20 mM的亚硝酸盐，这一浓度高于此前文献报道的其他酵母的耐受浓度。确定了最佳生长条件（50 mM磷酸钾缓冲液pH 7、20 g/L葡萄糖作为唯一碳源以及10 mM亚硝酸盐）。从无机氮去除应用的角度出发，还评估了与工艺优化相关的其他代谢特性，包括可再生资源利用和重金属耐受性。糖蜜、玉米和大豆油是良好的底物，且该菌株对镉和铅具有良好的耐受性。放大试验也揭示了其在大规模应用方面的良好特性。总体而言，所呈现的结果表明DSBCA06同化氮作为一种用于生物修复和处理废水流出物的创新工具具有应用潜力。
