Acid whey is a Greek-yogurt waste stream and can be a resource to produce biofuel precursors. Our objective was to convert acid whey into medium-chain carboxylic acid (MCCA) oil with the open-culture carboxylate platform. Here, we developed a temperature-phased bioprocess with different anaerobic reactor microbiomes, performing thermophilic lactic acid production and mesophilic chain elongation, to produce MCCAs (C6–C9) from acid whey via lactic acid as an intermediate. For the lactic acid-producing bioreactor, we achieved a volumetric lactic acid production rate of 1,230 mmol C L⁻¹ day⁻¹ (1.54 g L⁻¹ hr⁻¹). For the chain-elongating bioreactor, we achieved a volumetric MCCA production rate of 111 mmol C L⁻¹ day⁻¹ and a volumetric n-caproic acid (C6) production rate of 81 mmol C L⁻¹ day⁻¹ (0.07 g L⁻¹ hr⁻¹). We converted a real waste stream into mainly MCCAs without the external addition of an electron donor.

酸乳清是希腊酸奶的废物流，可以作为生产生物燃料前体的资源。我们的目标是通过开放培养的羧酸盐平台将酸乳清转化为中链羧酸（MCCA）油。在这里，我们开发了一个具有不同厌氧反应器微生物组的温度阶段生物工艺，进行嗜热乳酸生产和嗜温链延伸，从而通过乳酸为中间体从酸乳清生产MCCA（C6-C9）。对于生产乳酸的生物反应器，我们实现了1,230 mmol CL ^-1 day ^-1（1.54 g L ^-1 hr ^-1）的体积乳酸生产速率。对于链延长生物反应器，我们的MCCA体积生产率达到111 mmol CL ^-1第^-1天^-1的正己酸（C6）的生产速率为第^-1天^-1 CL ^-1（0.07 g L ^-1 hr ^-1）。我们将真实的废物流主要转化为MCCA，而无需外部添加电子供体。