(593k) Overproduction of Pleuran: An Immunemodulator Exopolysaccharide Produced in Submerged Culture of Pleurotus Ostreatus in Stirred Tank Bioreactor

El Enshasy, H.A^1,2

¹Institute of Bioproduct Development (IBD), Universiti Teknologi Malaysia (UTM), 81310 Skudai, Johor, Malaysia

²City for Scientific Research and Technology Applications, New Burg Al Arab, Alexandria, Egypt

Corresponding author: roslinda@ibd.utm.my

 Abstract

Pleurotus ostreatus, is an edible mushroom traditionally used for medicinal purpose since thousand years. In folk medicine, it’s claimed that this mushroom could be used for healing power as well to increase human longevity. Mushrooms show organoleptic properties due to their low caloric value, low fat content and high levels of protein, minerals and some polysaccharides. The bioactive polysaccharides produce from P. ostreatus are of special medicinal importance based on their potential activity as immunodulator, anticancer, anti-bacterial, and anti-tumour properties. Bioactive polysaccharides Pleuran with chemical formula of (C₆H₁₀0₅)_n is one of the most important glucose polymers and belongs to (β-(1,3/1,6)-D-glucan group. Nowadays, Submerged Fermentation (SMF) has been developed for mycelium propagation to get high biomass production and polysaccharides production for dietary supplement and pharmaceutical application for many types fungus, including P. ostreatus. Cultivation of mushroom in SMF is very promising technology because of the possibility to obtained high biomass production in a compact space with control environment, high yield, shorter time and less contamination. Therefore, objective of this study was to maximize exopolysaccharide (EPS) production by P. ostreatus through process optimization in both of shake flask and bioreactor cultures. In shake flask cultures, the maximal EPS volumetric production of 1.25 g/L with specific EPS production of about 0.19 g/g was obtained after 13 days cultivation. After that, production of EPS was scale up in 16-L in a batch stirred tank bioreactor under controlled and uncontrolled pH conditions at 26°C and 400 rpm using two 6-bladed Rushton turbine impellers (d_i, impeller diameter = 85 mm; d_t, tank diameter = 214 mm, ^di/_dt=0.397, 1 v/v/min, with working volume of 8-L. After 20 days cultivation, the maximal biomass and EPS production of 4.48 g/L and 1.97 g/L, were obtained respectively. When cells cultivated under controlled pH of 5.5, higher EPS production of about 30% was obtained compared to uncontrolled pH culture. Furthermore, the effect of different aeration rates ranged between 0.5 up to 2.0v/v/min was studied. The results were clearly demonstrated the maximal cell culture and specific EPS production of about 3.1 g/L and 0.58 g/g, respectively, were obtained in 1.5v/v/min aerated culture. In conclusion, the results presented in this work clearly demonstrate successful industrial production of Pleuran and critical role of bioprocessing parameters in this production process.