Optimization of aeration and agitation rate for lipid and gamma linolenic acid production by Cunninghamella bainieri 2A1 in submerged fermentation using response surface methodology.

Normah Saad,Aidil Abdul Hamid,Wan Mohtar Wan Yusoff,Mohd Sahaid Kalil,Peyman Abdeshahian

doi:10.1155/2014/280146

Abstract

The locally isolated filamentous fungus Cunninghamella bainieri 2A1 was cultivated in a 5 L bioreactor to produce lipid and gamma-linolenic acid (GLA). The optimization was carried out using response surface methodology based on a central composite design. A statistical model, second-order polynomial model, was adjusted to the experimental data to evaluate the effect of key operating variables, including aeration rate and agitation speed on lipid production. Process analysis showed that linear and quadratic effect of agitation intensity significantly influenced lipid production process (P < 0.01). The quadratic model also indicated that the interaction between aeration rate and agitation speed had a highly significant effect on lipid production (P < 0.01). Experimental results showed that a lipid content of 38.71% was produced in optimum conditions using an airflow rate and agitation speed of 0.32 vvm and 599 rpm, respectively. Similar results revealed that 0.058 (g/g) gamma-linolenic acid was produced in optimum conditions where 1.0 vvm aeration rate and 441.45 rpm agitation rate were used. The regression model confirmed that aeration and agitation were of prime importance for optimum production of lipid in the bioreactor.

Highlights

The extensive research studies have been carried out over the last decades to develop lipid production
Two independent variables were controlled at the levels determined by experimental design, which were represented as −1.41, −1, 0, 1, and 1.41 (Table 1)
Treatment 7 showed high levels of lipid and gammalinolenic acid (GLA) concentrations with values as high as 4.74 gram per liter of culture medium (g/L) and 747.72 mg/L, respectively, where aeration and agitation rates were set at 1.14 vvm (1.41 as a coded value) and 400 rpm (0 as a coded value)

Summary

Introduction

The extensive research studies have been carried out over the last decades to develop lipid production. These attempts have aimed at improving the economic production of microbial lipids rather than plant and animal derived oils. Zygomycetes have shown to produce microbial oil from organic substances [3, 4]. Previous studies have revealed that a high amount of lipid could be accumulated by the fungal strains of Cunninghamella spp. depending on the fermentation methods and culture conditions [5, 6]. Similar studies have shown that a high lipid accumulation is attained by Cunninghamella bainieri 2A1 in shake flask culture [7].

Methods

Results

Conclusion