Description

ASSIGNMENT

Question 1: Cellulase enzymes production (LO 2)

Enzymes have been well known as the industrial products since decades and its potential applications in various industry is expanding drastically. Cellulase enzymes is one of the many that have various applications in the industry. Mold is the competent producer of cellulase and its production is strongly induced by cellulose.

Questions for discussion

1.    State three applications of cellulase enzymes.

(3 marks)

2.    Solid state fermentation and submerged fermentation are the two major techniques in

enzymes production. Briefly describe both techniques and discuss the advantages of solid state fermentation over submerged fermentation.

(7 marks)

3.    You are the design engineer who is responsible to design a reactor for cellulase

production by using agricultural waste such as rice husk as the feedstock. Propose suitable operating condition such as types of fermentation technique, nutrients solution and fermentation conditions (i.e. temperature, pH, oxygen content, type of microorganism and inoculum loading) for the reactor.

(10 arks)

4.      Cellulase enzymes produced from fermentation was then applied in bioethanol

production. Cellulase enzymes play the role in hydrolysis of cellulose to form glucose. The hydrolysis can be done by either using free enzymes or immobilized enzymes. Your research team proposed to apply immobilized enzymes technology in the hydrolysis process. Choose an immobilization technique and briefly discuss on its procedure.

(5 marks)

[Total: 25 marks]

Question 2: Downstream processing (LO 3)

1. DNA in fruits could be isolated and extracted by using several steps. Utilize the RIPP scheme to describe the steps applied to extract DNA into ethanol phase and justify why these steps are taken.

(8 marks)

2. Discuss on the working principles, advantages and disadvantages for (1) homogenization and (2) ultrasonication methods in cell disruption.

(8 marks)

3. Centrifugation method is applied to separate the cells from the fermentation broth. Assuming that all the cells are spherical with diameter 3 μm and density 1.1 g cm-3. The viscosity of the culture broth is 1.5 × 10-3 N s m-2. At the temperature of separation, the density of the suspending fluid is 0.98 g cm-3. Eight hundred liters of broth must be treated every hour.

a. Identify the suitable Σ for a disc stack centrifuge.

b. Evaluate whether a centrifuge with Σ = 100 m2 is sufficient for the separation of cells from liquid.

c. Evaluate how size of the cells would impact the angular velocity applied in centrifugation.