Sains Malaysiana 43(3)(2014): 443–449

Effects of Mg²⁺, Fe³⁺, Mn²⁺ and Cu²⁺ Ions on Lipid Accumulation by

Cunninghamella bainieri 2A1

(Kesan Ion Mg²⁺, Fe³⁺, Mn²⁺ dan Cu²⁺ dalam Pengumpulan Lipid oleh Cunninghamella bainieri 2A1)

VIDYAH MANIKAN¹, MOHD SAHAID KALIL², OTHMAN OMAR¹, ABDUL JALIL ABDUL KADER³ & AIDIL ABDUL HAMID¹*

¹School of Biosciences and Biotechnology, Faculty of Science and Technology

Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia

²Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment

Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia

³Faculty of Science and Technology, Universiti Sains Islam Malaysia, 71800 Nilai,

Negeri Sembilan, Malaysia

Diserahkan: 8 Disember 2012/Diterima: 11 Julai 2013

ABSTRACT

Cunninghamella bainieri 2A1 is an oleaginous fungus whose lipid accumulation profile is significantly influenced by metal ion concentrations in growth medium. Mg²⁺, Fe³⁺, Mn²⁺ and Cu²⁺ were found to be the important elements affecting lipid accumulation in this fungus. This study employs a statistical method (Response Surface Methodology – RSM) to study the combined effects of Mg²⁺, Fe³⁺, Mn²⁺ and Cu²⁺ on lipid accumulation of C. baineri 2A1. Cultivation was carried out in 250 mL Erlenmeyer flasks containing 100 mL nitrogen limited medium at 30ºC and 250 rpm agitation for 120 h. A thirty-run central composite design experiment was employed to identify and optimize the significant factors. In addition to Mg²⁺ and Fe³⁺ which were shown to have significant effects on lipid accumulation, the interactions between Mg²⁺ and Cu²⁺, as well as the effect of Cu²⁺ in quadratic terms were also found to have significant effect on the process (p<0.05). The highest amount of lipid obtained in this study was 39% g/g biomass with optimal levels of Mg²⁺, Fe³⁺ and Cu²⁺ at 5.00, 0.017 and 0.0005 g/L, respectively, while Mn2+ was omitted. A 32% increment in lipid yield was recorded, where the lipid content increased to 38%, compared to initial yield of 29% g/g biomass prior to optimization. In conclusion, Mg²⁺ and Fe³⁺ have significant positive effect on the lipid accumulation of this fungus, whereas Mn²⁺ and Cu²⁺ exert negative effects in combination.

Keywords: Cunninghamella; metal ions; response surface methodology; single cell oil

ABSTRAK

Cunninghamella bainieri 2A1 merupakan kulat oleaginous dengan profil pengumpulan lipidnya dipengaruhi secara signifikan oleh kepekatan ion logam dalam medium pertumbuhan. Mg²⁺, Fe³⁺, Mn²⁺ dan Cu²⁺ adalah elemen penting yang mempengaruhi proses pengumpulan lipid dalam kulat ini. Kajian ini membabitkan penggunaan kaedah statistik (RSM) untuk mengkaji kesan kombinasi Mg²⁺, Fe³⁺, Mn²⁺ dan Cu²⁺ ke atas pengumpulan lipid oleh C. baineri 2A1. Pengkulturan dilakukan dalam kelalang goncangan 250 mL yang mengandungi 100 mL medium terhad nitrogen pada suhu 30ºC dengan kadar goncangan 250 rpm. Set eksperimen yang terdiri daripada 30 larian reka bentuk gubahan memusat telah digunakan untuk mengenal pasti dan mengoptimumkan faktor yang signifikan. Di samping Mg²⁺ dan Fe²⁺ yang didapati mempunyai kesan yang signifikan ke atas proses pengumpulan lipid, interaksi antara Mg²⁺ dan Cu²⁺ serta kesan Cu²⁺ pada terma kuadratik juga mempunyai kesan yang signifikan dalam proses ini (p<0.05). Peratus lipid maksimum yang tercapai adalah sebanyak 39% g/g biojisim dengan tahap optimum bagi Mg²⁺, Fe³⁺ dan Cu²⁺ pada kepekatan 5.00, 0.017 dan 0.0005 g/L masing-masing, manakala Mn2+ tidak dimasukkan. Peratus peningkatan penghasilan lipid adalah sebanyak 32% dan ia meningkat kepada 38% berbanding dengan 29% g/g biojisim sebelum pengoptimuman. Kesimpulannya, Mg²⁺ dan Fe³⁺ mempunyai kesan positif yang signifikan ke atas proses pengumpulan lipid oleh kulat ini, manakala Mn²⁺ dan Cu²⁺ mempunyai kesan negatif secara kombinasi.

Kata kunci: Cunninghamella; ion logam; kaedah gerak balas permukaan; minyak sel tunggal

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*Pengarang untuk surat-menyurat; email: aidilah@pkrisc.cc.ukm.my