Optimization of Pre-Inoculum, Fermentation Process Parameters and Precursor Supplementation Conditions to Enhance Apigenin Production by a Recombinant Streptomyces albus Strain

Simona Barbuto Ferraiuolo,Riccardo Ventriglia,Odile Francesca Restaino,Chiara Schiraldi,Claudio J Villar,Marcella Cammarota,Felipe Lombó,Ignacio Gutiérrez-Del-Río

doi:10.3390/fermentation7030161

Abstract

Streptomyces albus J1074-pAPI (Streptomyces albus-pAPI) is a recombinant strain constructed to biotechnologically produce apigenin, a flavonoid with interesting bioactive features that up to now has been manufactured by extraction from plants with long and not environmentally friendly procedures. So far, in literature, only a maximum apigenin concentration of 80.0 µg·L−1 has been obtained in shake flasks. In this paper, three integrated fermentation strategies were exploited to enhance the apigenin production by Streptomyces albus J1074-pAPI, combining specific approaches for pre-inoculum conditions, optimization of fermentation process parameters and supplementation of precursors. Using a pre-inoculum of mycelium, the apigenin concentration increased of 1.8-fold in shake flask physiological studies. In 2L batch fermentation, the aeration and stirring conditions were optimized and integrated with the new inoculum approach and the apigenin production reached 184.8 ± 4.0 µg·L−1, with a productivity of 2.6 ± 0.1 μg·L−1·h−1. The supplementation of 1.5 mM L-tyrosine in batch fermentations allowed to obtain an apigenin production of 343.3 ± 3.0 µg·L−1 in only 48 h, with an increased productivity of 7.1 ± 0.1 μg·L−1·h−1. This work demonstrates that the optimization of fermentation process conditions is a crucial requirement to increase the apigenin concentration and productivity by up to 4.3- and 10.7-fold.

Highlights

IntroductionFermentation 2021, 7, 161 cycle arrest and apoptosis [5,6]
Initial physiological studies were performed in shake flasks in order to investigate whether seeding the cultures directly with a mycelium pre-inoculum instead of spores would influence the apigenin production ability of Streptomyces albus-pAPI
The L-tyrosine was quickly up-taken: half of the amount was consumed in 24 h, g cdw biotechnological production of drugs and other bioactive compounds, thanks to their and it was completely used by the microorganism in only

Summary

Introduction

Fermentation 2021, 7, 161 cycle arrest and apoptosis [5,6]. These properties, in addition to low toxicity and poor adverse effects, have recently made apigenin an interesting molecule in cancer prevention or as an adjuvant in the treatment of breast, lung, liver, skin, blood, colon, prostate, pancreatic, cervical, oral and stomach tumors [6,7,8,9,10,11,12]. Apigenin anti-inflammatory and antioxidant properties proved useful in the prevention of inflammatory events associated with obesity, atherogenesis and osteoarthritis [13,14,15,16] and in the alleviation of the symptoms of neurodegenerative diseases, such as Alzheimer’s or Parkinson’s, and of depression [17,18]

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Discussion

Conclusion