有机碳对海洋着色菌YL28去除无机三态氮的影响

Effect of organic carbons on the removal of inorganic nitrogen coexisting in marine aquaculture by a marine purple sulfur bacterium, Marichramatium gracile YL28

摘要:

【目的】在无机三态氮(氨氮、亚硝氮和硝氮)共存的模拟海水水体中，阐明有机碳尤其是海藻寡糖对海洋着色菌(Marichromatium gracile) YL28生长及去除无机三态氮的影响规律。【方法】采用次溴酸钠氧化法、N-(1-萘基)-乙二胺分光光度法和紫外分光光度法分别测定水体中氨氮、亚硝氮和硝氮的含量，菌体生物量采用比浊法测定。【结果】在光照厌氧环境中，小分子有机酸盐(乙酸钠、丙酮酸钠、琥珀酸钠和柠檬酸钠)是YL28生长和去除无机三态氮的良好有机碳，亚硝氮、硝氮和氨氮去除率分别达到97.92%、99.98%、73.23%?87.15%。单糖(葡萄糖和果糖)、双糖(麦芽糖和蔗糖)和寡糖(壳寡糖和海藻寡糖)是YL28可利用的有机碳，亚硝氮和硝氮去除率分别达到99%和87%以上，氨氮去除率在44.82%?54.53%之间。多糖(β-环糊精、淀粉、黄原胶、琼脂粉、海藻酸钠和卡拉胶)不是菌体利用和去除无机三态氮的有机碳。酵母提取物可作为菌体生长、去除硝氮和亚硝氮的良好有机碳，但严重抑制氨氮去除。海藻酸钠、β-环糊精和卡拉胶分别与乙酸钠共存时，YL28生长和对无机三态氮去除能力与乙酸钠为唯一有机碳的水平相当。乙酸钠体系中添加海藻寡糖，YL28生长速率、最大生物量以及氨氮的去除速率和最大去除率均升高，添加酵母提取物时，生长速率和最大生物量升高，但氨氮去除速率和最大去除率降低。黑暗厌氧环境下，以乙酸钠和氨氮为唯一有机碳和氮源时，YL28不生长，但在无机三态氮共存时，则能良好生长并去除无机三态氮。【结论】在无机三态氮共存海水体系和厌氧条件下，无论是光照还是黑暗环境，YL28均能良好地生长和去除无机三态氮，小分子有机酸盐(乙酸钠、丙酮酸钠、琥珀酸钠、柠檬酸钠)是其良好的有机碳，相对而言，乙酸钠和丙酮酸钠更好。海藻寡糖与乙酸钠复合可提高菌体生长和脱氮能力。本研究为研制开发高效脱氮微生物制剂及其合理性应用提供了指导。

Abstract:

[Objective] Inorganic nitrogens (ammonium, nitrate and nitrite) existed simultaneously in complicated mariculture water. This work aims to explore the effects of organic carbons, especially seaweed oligosaccharides on the removal of inorganic nitrogens by a marine purple sulfur bacterium Marichramatium gracile YL28, which is capable of growth on nitrite as sole nitrogen source. [Methods] Sodium hypobromite oxidation, N-(1-naphthyl)-1,2-diaminoethane dihydrochloride spectrophotometry, and UV spectrophotometry were used for the determination of ammonia, nitrite and nitrate, respectively. Biomass was measured by turbidimetry. [Results] Under anaerobic light condition, organic acid salts (acetate, pyruvate, succinate, citrate) were better carbon sources for YL28, and the removal rate of ammonia, nitrate and nitrite reached 97.92%, 99.98%, and 73.23%?87.15%, respectively. Monosaccharides (glucose and fructose), disaccharides (sucrose and maltose) and oligosaccharides (chito-oligosaccharide and seaweed oligosaccharides) were also suitable for YL28 growth. The remove rate of nitrite and nitrate reached more than 99% and 87%, respectively. While the remove rate of ammonia was 44.82%?54.53%. YL28 had poor growth when polysaccharides (alginate, β-cyclodextrin, starch, xanthan gum, carrageenan and agar) as carbon sources. Yeast extract is favorable for YL28 growth, but it severely inhibited the removal of ammonia. Interestingly, the cell growth and inorganic nitrogen removal in combination of poor and good carbon source systems was equally well to that in good carbon source system. The combination of seaweed oligosaccharides and acetate sodium or yeast extract and acetate sodium promoted the increasing growth rate and biomass, however, there was a significantly different in removal rate of ammonium, seaweed oligosaccharides promoted the removal rate of ammonia, while yeast extract not. Under anaerobic dark condition, when using sodium acetate and ammonia as sole carbon or nitrogen source, YL28 grew poorly. However, under coexisting inorganic nitrogen environment, YL28 not only grew well but also removed efficiently inorganic nitrogen. [Conclusion] In coexisting inorganic nitrogen environment, whatever anaerobically in the light or dark, YL28 grows well and has better removal capacity to inorganic nitrogen. Organic acid salts are better carbon sources, sodium acetate is most suitable carbon source. The combination of seaweed oligosaccharides and sodium acetate could significantly promote cell growth and removal of inorganic nitrogen. This study provides valuable information for the development of higher efficiency water cleaner for sustainable mariculture.