Study the influence of nitrogen on rennin production by fungi Rhizomucor miehei using solid-state fermentation

Houthail Alahmad Aljammas ,Hassan Al-Fathi,W Alkhalaf ,Anton Taifor

doi:10.21472/bjbs.030517

Abstract

The effect of different nitrogen resources on the biosynthesis of milk clotting enzyme by Rhizmucor miehei was studied under solid state fermentation using wheat bran as base medium. Urea, peptone, albumin, casein, yeast extract were added with different concentrations (1%-10%). The response parameters were the ratio of milk clotting activity (MC) to proteolytic activity (PA) and protein content. The highest enzyme yield was achieved with casein at a rate of 2% w/w followed by 2% yeast extract, 1% albumin, 1% peptone, and 1% urea with values 5.6, 4.9, 4.2, 4, 3 mg/mL, respectively. Maximum enzyme activity (MCA/PA) was 50.4, 44.1, 37.8, 36, 27 SU for casein, yeast extract, albumin, peptone, and urea, respectively.

Highlights

Rennet enzyme is used in the manufacture of cheese, which is an acid protease, the effect of acid protease appears in the process of milk coagulation through two stages: in the first stage or enzymatic, casein hydrolyzed by rennin to produce para-casein which form the curd in the second phase
In this paper we studied the effect of supplying fermentation medium with deferent nitrogen resources; Urea, peptone, albumin, casein, yeast extract on biosynthesis of protease by fungi Rhizomucor miehei under solid state fermentation
The main role of protease production is to degradation of complex proteins to simple composition protein easy consumed through cell (Rao et al, 1998)

Summary

Introduction

Rennet enzyme (rennin) is used in the manufacture of cheese, which is an acid protease, the effect of acid protease appears in the process of milk coagulation through two stages: in the first stage or enzymatic, casein hydrolyzed by rennin to produce para-casein which form the curd in the second phase (non-enzymatic). Many of Microorganism give the enzyme rennin, but it is not suitable as substitutes for rennet since it should satisfy the following requirements; its proteolytic activity should be similar to calf rennet, should be able to curdle milk at the same conditions (calcium ion concentration, pH and temperature), effective coagulation of milk without undue hydrolysis of curd, proper flavor. Consume the substrate slowly and gradually so it can be used for a long period of fermentation, do not need continuously mixing to bring homogeneity, ventilation processes simple, it does not require sophisticated technology, which need less energy and occupy less space (Al-Khafaji, 1990) These advantages have made this system favorable in production of exoenzyme,mono-cell proteins, fermented foodstuff, toxins, organic acids, and some industrial chemicals, invertase, cellulose, lactase, aminoglycosides, pectinase and fungal protease. In this paper we studied the effect of supplying fermentation medium with deferent nitrogen resources; Urea, peptone, albumin, casein, yeast extract on biosynthesis of protease by fungi Rhizomucor miehei under solid state fermentation

Materials and methods

Results and discussion

Conclusion