Orchestration an extracellular lipase production from Aspergillus niger MYA 135: biomass morphology and fungal physiology

Abstract

The impact of biomass morphology and culture conditions on fungal fermentation was widely reviewed in the literature. In this work, we presented three independent experiments in order to evaluate the influence of some of those input factors on a lipase production separately by using the Aspergillus niger MYA 135 and the two-stage fermentation technique. Regarding the culture modality, the biomass was pre-grown in a first reactor. Then, the washed mycelium was transferred to a second reactor to continue the study. Firstly, linear effects of fungal morphology and several physiological parameters on a lipase production were explored using the Plackett–Burman design. The dispersed fungal morphology was confirmed as a proper quality characteristic for producing an extracellular lipase activity. Concerning the impact of the carbon source on the biomass pre-growth, the sucrose (E = 9.923, p < 0.001) and the l-arabinose (E = 4.198, p = 0.009) presented positive and significant effects on the enzyme production. On the contrary, the supplementation of 0.05 g/L CaCl₂ displayed a highly negative and significant effect on this process (E = − 7.390, p < 0.001). Secondly, the relationship between the enzyme production and the input variables N:C ratio, FeCl₃ and olive oil was explored applying the central composite design. Among the model terms, the N:C ratio of the production medium had the most negative and significant influence on the enzyme synthesis. Thus, it was concluded that a low N:C ratio was preferable to increase its production. In addition, the bifunctional role of FeCl₃ on this fungus was presented. Thirdly, a prove of concept assay was also discussed.