Sains Ma1aysiana 28: 49-57 (1999)                                                                                                               Sains Hayat/

                                                                                                                                                                                Life Science

Effect of pH and Agitation on Growth of Bacillus subtilis

Noorhisham Tan Kofli & Mohd. Sahaid Kalil

Department of Chemical and Process Engineering

Faculty of Engineering, Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor D.E. Malaysia

ABSTRACT

The effect of initial pH of medium (6.0,6.5 and 7.2) and agitation (100,200 and 300 rpm) on growth of oxygen sensitive culture of Bacillus subtilis were studied using shake flask cultures. Two type of media used were complex medium (CM) and well defined medium (WDM3). The effect of both parameters and types of media on production of acetoin and 2,3-butanediol were also studied. The maximum growth was detected in experiment with agitation at 300 rpm and pH 6.5 for both CM (2.87 g/l dry weight) and WDM3 (3.33 g/l dry weight). The use of WDM3 gave higher total products (acetoin+butanediol) concentration (0.67 g/l) compare to CM (0.44 g/l)

ABSTRAK

Kesan pH awal (6.0, 6.5 dan 7.2) dan kesan kelajuan goncangan (100, 200 dan 300 ppm) bagi pertumbuhan kultur Bacillus subtilis yang sensitif kepada oksigen telah dikaji dengan menggunakan kultur kelalang goncangan. Dua jenis media iaitu medium kompleks and medium tertakrif telah digunakan. Kesan kedua-dua parameter ke atas penghasilan acetoin dan 2,3-butanediol juga dikaji. Pertumbuhan maksimum didapati berlaku dalam eksperimen dengan kelajuan goncangan 300 ppm dan pH 6.5 bagi kedua-dua yang menghasilkan biojisim 2.87 g/l berat kering bagi medium kompleks dan 3.33 g/l berat keriang bagi medium tertakrif. Penggunaan medium tertakrif memberikan kepekatan hasil total (acetoin + butanediol) yang lebih tinggi (0.67 g/l) berbanding medium kompleks (0.44 g/l).

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