Optimal conditions for mycelia biomass and extracellular polysaccharides of Grifola frondosa: Effect of agitation speed, inoculum ratio and initial pH

African Journal of Biotechnology Vol. x(xx), pp. xxx-xxx, xx xxxxx, 2012

Available online at http://www.academicjournals.org/AJB

DOI: xxxxxxxxxxxxxxxxxx

ISSN 1684–5315 © 2012 Academic Journals

Full Length Research Paper

Optimal conditions for mycelia biomass and

extracellular polysaccharides of Grifola frondosa:

Effect of agitation speed, inoculum ratio and initial pH

Huu-Nghi Nguyen1

, Tzu-Ching Wang2

, Ta-Chen Lin3

and Jia-Hsin Guo4

*

1Department of Biotechnology and Food Technology, Thai Nguyen University of Agriculture and Forestry, Thai Nguyen,

Vietnam.

2 Department of Food and Beverage Management Section, Tzuhui Institute of Technology, Pingtung 92641, Taiwan,

Republic of China.

3Department of Hospitality, Nanya Institute of Technology, Taoyuan County 32091, Taiwan, Republic of China.

4Department of Food Science and Technology, National Pingtung University of Science and Technology, Pingtung,

91201, Taiwan, Republic of China.

Accepted 1 March, 2012

Grifola frondosa, a medicinal and edible mushroom, has shown different bioactive compounds, such as

polysaccharides with anticancer and other therapeutic properties. In the present research, the mycelia

of G. frondosa were cultivated in shaking flasks to investigate the effects of agitation speeds, inoculum

ratios, and initial pH on pellet morphology, biomass, and extracellular polysaccharide (EPS) production.

Furthermore, mathematical models for optimizing the three factors for biomass and EPS production

were developed. The results show that the culture parameters including agitation speed, inoculum ratio,

and initial pH influenced pellet morphology, biomass, and EPS production. The optimal conditions for

biomass and EPS production were agitation speed at 105 and 111 rpm, inoculum ratio 3.1 and 3.3%, and

initial pH 5.5 and 5.6, respectively. Under these conditions, the predicted maximum biomass and EPS

were 5.28 and 2.35 mg/ml, respectively. The findings may be useful for future development of

fermentation techniques for the production of G. frondosa products.

Key words: Grifola frondosa, biomass, extracellular polysaccharides, optimization.

INTRODUCTION

Mushrooms are an abundant source of useful natural

products and new compounds with interesting biological

properties. Of the 14000 known mushroom species, an

estimated 2000 are edible, but few have been thoroughly

studied in terms of their commercial potential. Zhong and

Tang (2004) reported that fewer than 25 species of

mushrooms are widely accepted as foods and only a very

few species have attained commercial significance.

Historically, medicinal mushrooms have been shown to

have profound health benefits and ongoing studies are

*Corresponding author. E-mail: [email protected]. Tel:

+886-8-7740222. Fax: +886-8-7740173

now confirming their medical potential and identifying

many of their bioactive compounds. Smith et al. (2002)

mentioned that medicinal mushrooms are considered to

be a rapidly developing area of biotechnology for

therapies for cancer and other diseases. In particular,

mushrooms represent an unlimited source of poly￾saccharides with antitumor and immunomodulating

properties. Wasser (2002) observed that many

basidiomycetes mushrooms contain biologically active

polysaccharides such as beta-D-glucan in their fruiting

bodies, cultured mycelium, and culture broth. Recently,

Wasser and Weis (1999) isolated and identified a number

of substances from the basidiomycetes mushroom, which

have antitumor, immunomodulating, cardiovascular,

antihypercholesterol, antibacterial, antiviral, antiparasitic,