A. R. Omar^1* and K. A. Schat

^*1Department of Veterinary Pathology and Microbiology, Faculty of Veterinary Medicine and Animal Science, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia, Department of Microbiology and Immunology,
College of Veterinary Medicine, Cornell University, Ithaca, NY 14850, USA.

(Received 8 December 1997 / Accepted 10 January 1998)

Abstract.
Marek's disease virus (MDV) genes with homology to herpes simplex virus genes encoding for immediate early, early and late proteins and genes unique to MDV have been cloned and sequenced. Similarly, MDV genes that have significant homology to known oncogenes have also been characterized. Chickens vaccinated against this disease induce neutralizing antibody response and probably cytotoxic T lymphocyte activity that confer protection against subsequent challenge.

Keywords: Molecular Biology, Immunology, Marek's Disease Virus

A.M. Yazid^1*, M. Shuhaimi¹, A.M. Ali², M.H. Ghazali², J. Normah¹, A.B. Fatimah³,
N.A. Nur Atiqah4 and A. Reezal3

¹Department of Food Technology, ²Department of Biotechnology, ³Department of food Science, Faculty of Food Science and
Biotechnology, Universiti Putra Malaysia, 43400 Serdang, Selangor,
⁴Department of Paediatrics, Kuala Lumpur Hospital, Jalan Pahang, 50586 Kuala Lumpur, Malaysia

(Received 10 April 1999 / Accepted 29 July 1999)

Abstract.
The ability of eighteen strains of genus Bifidobacterium spp. to survive in a simulated gastric pH and tolerance to bile acids exposure was investigated. Four strains namely, B. bifidum (ATCC 35914), B. adolescentis (ATCC 11146), B. breve (ATCC 15698) and B. infantis (ATCC 27920) showed excellent growth following 90 min exposure to extreme acidic condition (pH 2.5). Strains B. breve (ATCC 15701) and B. adolescentis (ATCC 15706) showed good acid tolerance and another 2 strains (B. adolescentis ATCC 15705 and B. longum ATCC 15707) possessed moderate ability to tolerate exposure to low pH. The remaining 10 strains did not survive the extreme acid condition. The ability to grow in the presence of bile acids was variable among strains. Four strains (B. longum ATCC 15707 and ATCC 15708, B. adolescentis ATCC 11146 and B. asteroides ATCC 25910) showed good tolerance and another 5 strains (B. breve ATCC 15700 and 15701, B. asteroides ATCC 25909, B. bifidum ATCC 35914 and B. infantis ATCC 27920) showed moderate tolerance and the rest were sensitive to bile acids. No correlation was observed between the ability to survive extreme acidic condition and the ability to grow in the presence of bile. The strains that possess excellent acid tolerance were not necessarily tolerant to bile, and vice versa.

Keywords: Bifidobacteria, tolerance, pH, bile acids

A.R. NorAini¹, M.A. Hassan^1*, Y. Shirai², A.B. Ariff¹ and M.I.A. Karim¹

¹Department of Biotechnology, Faculty of Food Science and Biotechnology, Universiti Putra Malaysia,
43400 UPM Serdang, Selangor, Malaysia.
²Department of Biochemical Engineering and Science,
Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, Iizuka,
Fukuoka 820 8502, Japan.

(Received 4 March 1999 / Accepted 11 October 1999)

Abstract.
We have previously reported on the anaerobic treatment of palm oil mill effluent (POME) to produce organic acids as raw materials for PHA (polyhydroxyalkanoates) production (Hassan et al, 1997a). This study focused on optimisation of organic acids production as part of an integrated zero emission system. Optimisation of organic acids production was performed by continuous fermentation at four different retention times of 2.5, 5, 7.5 and 10 days until steady states were achieved. POME was mixed with an equal amount of anaerobic sludge in a 12 liter stirred tank bioreactor. The pH was controlled at 7.0 to produce organic acids, particularly acetic and propionic, from POME. Total organic acids produced were 7.7 to 9.6 g/L for 2.5, 5 and 7.5 days retention times. More than 75% of the chemical oxygen demand (COD) removal could be achieved during anaerobic treatment at 5, 7.5 and 10 days retention times. The best retention time was 5 days which produced 9.53 ±1.28 g/L of total organic acids with 11700 mg/L COD and 77% COD removal at steady state. After separation of the organic acids in the treated effluent by ion exchange chromatography, the residual COD was less than 100 mg/L which met the effluent standard set for the industry by the Department of Environment of Malaysia. The results obtained in this study establishes the possibility of integrating organic acids production from POME either within its conventional wastewater treatment system or in the zero emission system.

Keywords: Palm oil mill effluent, anaerobic treatment, organic acids, continuous culture

A. Kengluecha¹, W. Noonpakdee^1*, S. Sitthimonchai¹, R. Valyasevi² and S. Panyim¹

¹Department of Biochemistry, Faculty of Science, Mahidol University, ¹National Center for Genetic
Engineering and Biotechnology, NSTDA, Ministry of Science, Technology and Environment, Thailand

(Received 22 July 1999 l Accepted 5 October 1999)

Abstract.
Catalase activity is rarely found in lactobacilli but it is a desirable characteristic for starter cultures as it prevents defects caused by hydrogen peroxide in food product. The catalase gene from Lactobacillus sake SR91II was cloned and expressed in Escherichia coli UM2, Lactobacillus sp. TISTR891 and Lactobacillus plantarumTISTR850. The Lactobacillus sp.TISTR891 and L. plantarum TISTR850 isolated from local fermented meat products were naturally devoid of catalase activity. The transformed lactobacilli were shown to decompose hydrogen peroxide and the recombinant proteins were also detected by in situ activity staining of the catalase enzyme. The catalase gene was expressed as an active enzyme in transformed Lactobacillus sp. TISTR891 by using pGKV210, a lactococcus promoter screening vector. Increase in the expression of catalase gene by about two fold was observed after cloning the gene under the strong lactococcal promotor p59 located in the expression vector pIL 1020. In transformed Lactobacillus plantarum TISTR850, catalase activity was expressed almost 6 times as that in Lactobacillus sp. TISTR891 where expression was under the control of its own promoter.

Keywords: High level expression, catalase gene, Lactobacilli