Optimisation of culture conditions and development of a novel fed‐batch strategy for high production of β‐galactosidase by Kluyveromyces lactis

Abstract

Summary The aim of this study was to enhance β‐galactosidase production by Kluyveromyces lactis CICC1773. Firstly, the optimum culture conditions were obtained by response surface methodology, and the maximum β‐galactosidase activity reached 20.6 U mL−1, about two‐fold increase than that of the initial conditions (initial fermentation medium and conditions). To further improve β‐galactosidase production, a new fed‐batch strategy based on pH feedback control was developed successfully in a 7‐L fermenter, using 400 g L−1 lactose as feeding medium. As a result, the β‐galactosidase activity and productivity reached up to 111.61 U mL−1 and 5.31 U/(mL·h), enhanced by 15.3‐fold and 17.6‐fold superior than the results of initial conditions, respectively. To our knowledge, β‐galactosidase activity obtained was the highest value among the results reported by nonrecombinant strains. These results demonstrated that the new fed‐batch strategy based on optimum culture conditions could be automatic control easily and be conductive to further scale up for industrial fermentation.

Freshwater microalgae Nannochloropsis limnetica for the production of β-galactosidase from whey powder

“…This is well aligned with previous results reported for Nannochloropsis by Zanette et al 15 and Li et al 3 . The maximum extracellular β-galactosidase activity (40.84 ± 0.23 U L −1 ) measured in this study was similar to those secreted by other microalgae species 3 , 15 , 40 , but lower than those previously reported in other studies with bacteria and yeast 41 , 42 . Studies conducted by Suwal et al 18 and Li et al 3 reported similar patterns when cultivating Nannochloropsis on lactose-enriched standard medium, observing a peak of extracellular β-galactosidase activity roughly midway through cultivation before a sharp decrease.…”

Characterization of putative mannoprotein in Kluyveromyces lactis for lactase production

“…In this study, we obtained lactase activity of 146.04 U/mL in a 5 L fermenter, which is 1.31-fold higher than that of the previously reported non-recombinant K. lactis CICC1773 in a 7 L fermenter (111.61 U/mL) [ 8 ]. However, lactases from K. lactis are intracellular enzymes, leading to high costs in downstream processing, including the cell disruption and separation steps.…”

“…S7 ). pH is an important factor affecting lactase production, as it influences the electrical properties of the plasmalemma [ 8 ]. The lactase activity of K. lactis JNXR-2101 increased gradually when the pH was changed from 4.5 to 6.5.…”

“…In addition, strain engineering and fermentation optimization has been applied to improve the yield of lactase. You et al [ 8 ] optimized the fermentation conditions using response surface methodology for lactase production, and achieved a maximum yield of 111.61 U/mL lactase in K. lactis grown in fed-batch culture.…”