Sains Malaysiana 35(2):17-21 (2006)

Kajian Tindak Balas Candida albicans

Terhadap Tekanan Oksidatif

(The Study of Oxidative Stress Responses in Candida albicans)

Wan Noorhayati Wan Ibrahim, Farah Diba  Abu Bakar,

Nor Muhammad Mahadi & Abdul Munir Abdul Murad

Pusat Pengajian BioSains dan Bioteknologi

Fakulti Sains dan Teknologi

Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor

Abstrak

Kebolehupayaan Candida albicans pencilan klinikal tempatan untuk beradaptasi dan memberi tindakbalas terhadap tekanan oksidatif telah dikaji dalam penyelidikan ini. Perlakuan dengan hidrogen peroksida (H2O2) terhadap C. albicans mendedahkan sel kepada tekanan oksidatif  dan memberi kesan terhadap kadar pertumbuhan patogen oportunis ini.  Kadar pertumbuhan C. albicans dalam media Yis Pepton Dektrosa (YPD) dengan kehadiran 4.0 mM H2O2 telah memberi masa generasi 51 min/generasi, berbanding 44 min/generasi pada kepekatan 0.4 mM dan tanpa perlakuan dengan H2O2. Untuk mengkaji tahap kerintangan sel terhadap tekanan oksidatif, sel telah didedahkan kepada beberapa siri kepekatan H2O2 yang berbeza. Data menunjukkan peratus kemandirian sel berbanding kawalan menurun berkadar dengan peningkatan tekanan yang diberi. Ini membuktikan sel mempunyai tahap kerintangan tertentu terhadap tekanan oksidatif. Untuk mengenalpasti sama ada sistem pertahanan aruhan hadir di dalam C. albicans pencilan ini, sel telah didedahkan dengan kepekatan H2O2 yang rendah selama satu jam sebelum didedahkan kepada tekanan yang lebih tinggi. Didapati peratus kemandirian untuk sel yang menerima perlakuan dengan tekanan oksidatif lemah meningkat berbanding sel yang tidak menerima perlakuan awal. Ini menunjukkan bahawa mekanisme pertahanan aruhan untuk menghadapi tekanan oksidatif hadir di dalam C. albicans. Untuk mengenalpasti sama ada tekanan oksidatif mampu mengaruh morfogenesis yis menjadi hifa, sel telah didedahkan kepada 0.4 mM H2O2 pada  suhu 37ºC dan jumlah hifa yang terbentuk dikira dan dibandingkan dengan pembentukan hifa apabila sel didedahkan pada suhu 37 ºC sahaja. Hasil yang diperoleh menunjukkan bahawa tekanan oksidatif tidak memainkan peranan penting untuk mengaruh morfogenesis yis menjadi hifa dalam strain C. albicans pencilan klinikal tempatan ini.

Kata kunci: Candida albicans; tekanan oksidatif

ABSTRACT

The ability of a locally isolated clinical strain of C. albicans to adapt and response towards oxidative stress were investigated in this study. Treatment of C. albicans with hydrogen peroxide (H2O2) will exert an oxidative stress to C. albicans cells and affect the growth rate of this opportunistic pathogen. Cells that were grown in Yeast Peptone Dextrose (YPD) medium with the presence of 4.0 mM H2O2 gave a doubling time of 51 min/generation compared to 44 min/generation for those grown in 0.4 mM H2O2 and without H2O2. In order to determine the resistance level of C. albicans towards oxidative stress, cells were exposed to different concentration of H2O2. Results showed that percentage of cells viability decreased with the increased concentration of H2O2. These data indicated that C. albicans could overcome oxidative stress to a certain level before they were killed. To determine whether this strain exhibited a stress induce protection, cells were treated with mild oxidative stress for one hour before exposed to a stronger oxidative stress. Data obtained shows that cells that were pre-treated with mild oxidative stress showed higher percentage of survival compared to non pre-treated cells. This strongly suggested that stress induce protection was present in this C. albicans. Finally, in order to determine whether oxidative stress can induce yeast to hyphal morphogenesis in C. albicans, cells were then exposed to 0.4 mM H2O2 at 37ºC  and the number of hyphal formed were compared to hyphal formation when the cells were grown at 37 ºC only. However the results showed that oxidative stress failed to induce yeast to hyphal morphogenesis in this clinically isolated C. albicans strain.

Keywords: Candida albicans; oxidative stress

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