Impact of pH changes on neutral lipid production of the microalga Dunaliella tertiolecta isolated from Meke Crater Lake (Konya/Turkey)

Abstract

In this study, the impact of a change in pH of the growth medium on the production of triacylglycerol (used as a biodiesel feedstock) and related parameters were evaluated in a green halophilic microalga Dunaliella tertiolecta. Microalgae were cultured in Johnson's nutrient medium with different initial pH values (pH = 4, 6, 8, 10)  under suitable conditions for 25 days and growth was followed, triacylglycerol production and related parameters were analyzed. There was an increase in the growth rate, total chlorophyll and carotenoid contents, net oxygen production and consumption ratio did not show a significant change as accompanied by a remarkable increase of neutral lipid and triacylglycerol content of microalgae in proportion to a decrease in initial pH. On the other side, there was a decrease in the total chlorophyll and carotenoid content accompanied by a decrease in both oxygen production and consumption ration while there was no significant change in growth rate, neutral lipid, and triacylglycerol production of microalgae when the medium pH is adjusted as 10. Results show that lowering the initial pH of the growth medium might be used as a practical approach for induction of biodiesel feedstock production by Dunaliella tertiolecta.

Keywords

• Biodiesel,Dunaliella tertiolecta,pH

Meke Krater Gölü’nden (Konya/Türkiye) İzole Edilen Dunaliella tertiolecta Mikroalginin Nötral Lipid İçeriğine pH Değişimlerinin Etkisi

Öz

Bu çalışmada, halofil bir yeşil mikroalg olan Dunaliella tertiolecta’nın büyüme ortamındaki pH değişikliğinin biyodizel hammaddesi olarak kullanılan triaçilgliserol üretimi ve ilgili parametrelerde meydana gelen değişimi üzerine etkisi değerlendirilmiştir. Mikroalgler Johnson’s besin ortamında farklı pH’larda (pH=4, 6, 8, 10) 25 gün boyunca uygun şartlarda kültüre alınmış ve büyümeleri takip edilmiş, triaçilgliserol üretimleri ve ilgili parametreler analiz edilmiştir. Mikroalglerin büyüme ortamının başlangıç pH’sındaki düşüşle doğru orantılı olarak büyüme hızı, toplam klorofil ve karotenoid miktarlarında artış, net oksijen üretim ve tüketim hızında önemli bir değişim belirlenmezken nötral lipid ve triaçilgliserol üretiminde de artma olmuştur. Diğer taraftan ortam pH’sı 10 olarak ayarlandığında ise mikroalglerin çoğalma hızında önemli bir değişim belirlenmezken,  toplam klorofil ve karotenoid miktarlarında düşüş, net oksijen üretim ve tüketim hızlarında azalma olmuş, nötral lipid ve triaçilgliserol üretiminde dikkate değer bir değişim gözlenmemiştir. Elde edilen sonuçlar D.tertiolecta’dan biyodizel hammaddesi üretimi için ortam pH’sını düşürmenin etkili bir sonuç alınabilecek pratik bir yöntem olduğunu göstermiştir. 

Anahtar Kelimeler

• Biyodizel,Dunaliella tertiolecta,pH,Triaçilgliserol

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