Insights into Leveraging Alga–Bacterium Cooperation for Dairy Wastewater Valorization

The integration of microalgae-bacteria consortia into wastewater treatment offers a promising strategy for sustainable biomass production and bioremediation. This study investigates the performance of Chlamydomonas reinhardtii in consortium with Serratia liquefaciens DWW128, isolated from raw dairy wastewater (DWW). The consortium, and respective monocultures were cultivated in both untreated, raw DWW and sterile, simulated DWW (sDWW). C. reinhardtii alone exhibited negligible growth in sDWW, while the native microbial community of raw DWW supported its growth (35.2 µg·mL⁻¹ chlorophyll and 1.6 g·L⁻¹ of biomass). However, native microorganisms also negatively affect the alga by limiting its maximum growth compared to cocultures with S. liquefaciens in raw DWW (53.2 µg·mL⁻¹ chlorophyll, 3.1 g·L⁻¹ biomass) and in sDWW (90 µg·mL⁻¹ chlorophyll, 7.1 g·L⁻¹ biomass). The enhancement of algal growth is more pronounced under aerobic conditions, and the supply of ammonium through bacterial proteolytic activity, and possibly also acetic acid, are key factors for algal growth. Cocultures can reduce up to 57.6 % of the bacterial CO2 emissions. In contrast, S. liquefaciens did not depend on C. reinhardtii to grow successfully in DWW and can produce a substantial amount of bioH2 (200.7 mL·L-1) in 48 h. However, the presence of the alga enhances the bacterium´s viability and persistence. This study provides valuable insights into harnessing the metabolic specialization of diverse microalgal and bacterial species to design tailored consortia capable of exploiting the broad spectrum of nutrient sources in wastewater, enabling more robust and effective biotechnological applications

将微藻-细菌联合体（microalgae-bacteria consortia）应用于污水处理，可为可持续生物质生产与生物修复提供一条极具前景的策略。本研究探究了莱茵衣藻（Chlamydomonas reinhardtii）与从原乳清废水（raw dairy wastewater, DWW）中分离得到的液化沙雷氏菌（Serratia liquefaciens）DWW128构成的联合体的处理性能。该联合体及其对应的单一纯培养物，分别在未处理的原乳清废水与无菌模拟乳清废水（simulated DWW, sDWW）中进行培养。仅莱茵衣藻在无菌模拟乳清废水中的生长可忽略不计，而原乳清废水中的本土微生物群落可支撑其生长（叶绿素含量达35.2 μg·mL⁻¹，生物质浓度为1.6 g·L⁻¹）。但与液化沙雷氏菌共培养的体系相比，本土微生物群落也会对莱茵衣藻产生负面影响：在原乳清废水中，共培养体系的叶绿素含量可达53.2 μg·mL⁻¹、生物质浓度达3.1 g·L⁻¹；在无菌模拟乳清废水中则分别为90 μg·mL⁻¹与7.1 g·L⁻¹，本土微生物会限制莱茵衣藻的最大生长量。在有氧条件下，藻类生长的促进效果更为显著；细菌蛋白水解活性所提供的铵根离子，以及可能存在的乙酸，均是支撑藻类生长的关键因素。共培养体系可将细菌的二氧化碳排放量降低至多57.6%。与之相反，液化沙雷氏菌在乳清废水中生长并不依赖莱茵衣藻，且可在48小时内产生大量生物氢气（bioH2），产量达200.7 mL·L⁻¹。但莱茵衣藻的存在可提升液化沙雷氏菌的存活能力与存续时长。本研究为利用不同微藻与细菌的代谢特异性，设计可利用废水中多样营养源的定制化联合体提供了宝贵见解，助力开发更稳定高效的生物技术应用方案。