Macroparticle‐enhanced cultivation of Lentzea aerocolonigenes: Variation of mechanical stress and combination with lecithin supplementation for a significantly increased rebeccamycin production

Abstract

The actinomycete Lentzea aerocolonigenes produces the antitumor antibiotic rebeccamycin. In previous studies the rebeccamycin production was significantly increased by the addition of glass beads during cultivation in different diameters between 0.5 and 2 mm and the induced mechanical stress by the glass beads was proposed to be responsible for the increased production. Thus, this study was conducted to be a systematic investigation of different parameters for macroparticle addition, such as bead diameter, concentration, and density (glass and ceramic) as well as shaking frequency, for a better understanding of the particle‐induced stress on L. aerocolonigenes. The induced stress for optimal rebeccamycin production can be estimated by a combination of stress energy and stress frequency. In addition, the macroparticle‐enhanced cultivation of L. aerocolonigenes was combined with soy lecithin addition to further increase the rebeccamycin concentration. With 100 g L−1 glass beads in a diameter of 969 µm and 5 g L−1 soy lecithin a concentration of 388 mg L−1 rebeccamycin was reached after 10 days of cultivation, which corresponds to the highest rebeccamycin concentrations achieved in shake flask cultivations of L. aerocolonigenes stated in literature so far.

Morphology engineering for novel antibiotics: Effect of glass microparticles and soy lecithin on rebeccamycin production and cellular morphology of filamentous actinomycete Lentzea aerocolonigenes

“… Schrinner et al (2021) investigated the effect of soy lecithin supplementation on the cultivation of L. aerocolonigenes , also in combination with glass bead macroparticle addition (100 g·L −1 , x 50 = 969 μm). The presented results showed that lecithin is highly beneficial for rebeccamycin production in both cases, as a single supplement and in combination with macro-sized glass beads.…”

“…Accordingly, the rebeccamycin concentration increases slightly due to isolated supplementation of each additive but increases more than fourfold due to combined supplementation and reaches a maximum concentration of 213 mg·L −1 after 10 days of cultivation. Considering the AYC, due to an enhanced value for the combined supplementation, it can be concluded that the enhanced rebeccamycin production is not only the result of a higher biomass concentration in the culture broth but also of higher productivity of the cells themselves, e.g., by higher porosity of the biomass ( Schrinner et al, 2021 ) and as a result of an overall reduced AESD of the pellets (data not shown). Schrinner et al (2021) , for example, postulated lecithin to be an additional carbon source resulting in enhanced biomass growth.…”

“…All experiments were conducted in triplicate if not stated otherwise. Shaking flasks [four baffles, maximum inner diameter (d sf ) of 81.3 mm] were of the same design for all experiments to minimize influencing the hydrodynamic conditions by varying flask geometry ( Schrader et al, 2019 ; Schrinner et al, 2021 ).…”

“…As L. aerocolonigenes does not meet this requirement of high product titers naturally, a variation in morphology engineering techniques was applied to optimize rebeccamycin production in several recent studies. Supplementing glass macroparticles (100 g·L −1 glass beads with x 50 = 969 µm) led to an increased rebeccamycin production of about an order of magnitude ( Walisko et al, 2017 ; Schrader et al, 2019 ; Schrinner et al, 2020 ; Schrinner et al, 2021 ). Hereby, the application of glass beads induces defined mechanical stress to the culture broth and thus affects the cultivation in a profoundly different way than microparticles do by directly interacting with the hyphal network.…”

“…Hereby, the application of glass beads induces defined mechanical stress to the culture broth and thus affects the cultivation in a profoundly different way than microparticles do by directly interacting with the hyphal network. Additionally, Schrinner et al (2021) investigated the combined approach of macroparticle-enhanced cultivation (100 g·L −1 glass beads with x 50 = 969 µm) of L. aerocolonigenes and the addition of the emulsifier soy lecithin (5 g·L −1 ). So far, this combined supplementation generated the highest rebeccamycin concentration of 388 mg·L −1 after 10 days of cultivation reported in the literature for the shake flask scale.…”