Modelling growth kinetics of Streptomyces coelicolor A3(2) in a pressurised membrane gradostat reactor (MGR)

Lovastatin production by Aspergillus terreus in membrane gradostat bioreactor with two-stage feeding strategy

Lovastatin is a blood cholesterol-lowering agent and is produced as a secondary metabolite by Aspergillus terreus. Microbial production of this drug is carried out in solid-state or submerged culture, and due to difficulties of controlling the procedure parameters in solid-state method, the submerged method is conventional for industrial production. Although the submerged method is widely used, but this method damages the morphology of fungus due to shear stress caused by stirring. Since the morphology of fungus is a key factor in lovastatin production, using a bioreactor that causes the least damage to it, can improve the lovastatin production. In this paper, for the first time, it has been shown that the membrane gradostat bioreactor is suitable for lovastatin production, using A. terreus, due to providing suitable environmental conditions, therefore, it can be implemented as an alternative method for lovastatin production. Furthermore, it was found that implementing two-stage feeding, using different ratios of Carbon to Nitrogen in the culture medium, makes the lovastatin production to be 5 times more than one-stage feeding. Finally, it is shown that adding Zinc and Magnesium at the second stage further increases lovastatin production by 18%.

Agro-industrial wastes revalorization as feedstock: production of lignin-modifying enzymes extracts by solid-state fermentation using white rot fungi

The purpose of the study was to evaluate the production of lignin-modifying enzyme extracts and delignified biomass from agro-industrial wastes using white rot fungi (Inonotus sp. Sp2, Stereum hirsutum Ru-104, Bjerkandera sp. BOS55, Pleurotus eryngii IJFM 169 and Phanerochaete chrysosporium BKM-F-1767). These were screened based on their adaptability and colonization ability on different substrates, as well as by the Laccase, Manganese peroxidase, and Lignin peroxidase enzymatic production. Native strains (Inonotus sp. Sp2 and S. hirsutum Ru-104) showed the highest growth kinetics under the solid-substrate fermentation conditions and the growth rate parameters of the kinetic logistic model for the different substrates were between 0.39-0.81 (1/d) and 0.42-0.83 (1/d), respectively; the determination coefficients were ≥0.99. Inonotus sp. Sp2 was subsequently cultured in static flasks to produce crude enzyme extracts, obtaining manganese peroxidase activity levels of 18.5 and 31.3 (U/g) when growing in corn cob husk and spent tea leaves, respectively. Besides, it was to establish that the best conditions for lignin-modifying enzymes production using corn cob husk are 70% of initial moisture and 2.12 mm of particle size; reaching after 30 incubation days a manganese peroxidase activity of 21 ± 6 (U/g) under these conditions; enzyme that showed a suitable thermostability.

BIO-PRECIPITATES PRODUCED BY TWO AUTOCHTHONOUS BORON TOLERANT STREPTOMYCES STRAINS

Boron is widespread in the environment. Although contaminated soils are hard to recover different strategies have been investigated in the recent years. Bioremediation is one of the most studied because it is eco-friendly and less costly than other techniques. The aim of this research was to evaluate whether two Streptomyces strains isolated from boron contaminated soils in Salta, Argentina, may help remove boron from such soils. For this, they were grown in different liquid media with two boric acid concentrations and their specific growth rate and specific boric acid consumption rate were determined. Both strains showed great capacity to remove boron from the media. Increasing boric acid concentrations affected negatively the specific growth rate, however the specific boric acid consumption rate was superior. Boron bio-precipitates were observed when the strains grew in the presence of boric acid, probably due to an adaptive response developed by the cells to the exposure, for which many proteins were differentially synthetized. This strategy to tolerate high concentrations of boron by immobilizing it in bio-precipitates has not been previously described, to the best of our knowledge, and may have a great potential application in remediating soils contaminated with boron compounds.

Quorus bioreactor: a new perfusion-based technology for microbial cultivation

: This chapter briefly reviews perfusion-based cultivation solutions used in biomanufacturing. It further introduces the innovative single-use Quorus Bioreactor, which was designed for the efficient cultivation of nontraditional production cell types. The Quorus Bioreactor design, process control, and productivity are described. Case studies are presented using Aspergillus niger and Lactococcus lactis as model organisms to demonstrate process flexibility, efficiency, and scalability.