Liquid–liquid extraction by mixed micellar systems: A new approach for clavulanic acid recovery from fermented broth

This work is the first attempt to apply aqueous two-phase mixed micellar systems (ATPMS) of the nonionic surfactant Triton X-114 and the anionic one AOT to extract clavulanic acid (CA) from broth fermented by Streptomyces clavuligerus. Cloud points were determined in McIlvane buffer pH 6.5 with or without NaCl, and diagram phases/coexistence curves were constructed. CA partition was investigated following a 24-full factorial design in which AOT (0.022, 0.033 and 0.044% w/w), Triton X-114 (1.0, 3.0 and 5.0% w/w) and NaCl (0, 2.85 and 5.70% w/w) concentrations and temperature (24, 26 and 28 °C) were selected as independent variables, and CA partition coefficient (KCA) and yield in the top phase (ηCA) as responses. CA partitioned always to the top, micelle-poor phase. The regression analysis pointed out that NaCl concentration and interaction between temperature and Triton X-114 concentration had statistically significant effects on KCA, while ηCA was mainly influenced by temperature, Triton X-114 concentration and their interaction. Different ATPMS compositions were then needed to maximize these responses, specifically 0.022% (w/w) AOT, 5% (w/w) Triton X-114 for KCA (2.08), and 0.044% (w/w) AOT, 1% (w/w) Triton X-114 for ηCA (98.7%), both at 24 °C without NaCl. Since at 0.022% (w/w) AOT, 1% (w/w) Triton X-114 and 28 °C without NaCl the system was able to ensure satisfactory intermediate results (KCA = 1.48; ηCA = 86.3%), these conditions were selected as the best ones. These preliminary results are of concern for possible industrial application, because CA partition to the dilute phase can simplify the subsequent purification protocol.

► Clavulanic acid (CA) is a potent inhibitor of β-lactamases.
► Aqueous two-phase micellar systems were used with success to extract CA from broth fermented.
► Under all conditions studied CA partitioned to the dilute, micelle-poor phase.
► The system used has potential as a new first-step operation of CA purification.