Effects of molybdenum to growth parameters and lipid content of two algae in Scenedesmaceae taxa

Abstract

Molybdate, an oxidized form of molybdenum, facilitates molybdenum to be taken into cell, and thus to be included as a cofactor in the structure of enzymes necessary to ensure homeostasis. Although this compound provides the catalysis and electron transport of many biochemical reactions, it causes serious health problems in animals at high concentrations. For this reason, its recovery of water resources is one of the main subjects of scientific studies called bioremediaiton. One of the advantages of the remediation is that the biomass obtained from algae increases the amount of lipids, which are the raw material source for the biofuel production. For this purpose, the bioremediation abilities of Desmodesmus pannonicus and Scenedesmus aldavei algae were spectrophotometrically evaluated by using growth rate, chlorophyll-a, chlorophyll-b and total carotenoids for fourteen days. The bioremediation properties were also determined using Inductively coupled plasma - optical emission spectrometry (ICP-OES) analysis. D. pannonicus and S. aldavei algae have bioremediation capabilities up to 1 mg mL^-1 Na₂MoO₄ concentration. The lipid content increased at all concentrations in S. aldavei and at 200 μg mL^-1 in D. pannonicus. However, the Mo (VI) contents in dry mass changed depending on the increase of concentrations. Fourier Transform InfraRed Spectrometer analysis (FT-IR) was utilized to identify the alterations of specific functional groups such as carboxyl, amine, hydroxyl, and carbonyl in the samples. As a result, D. pannonicus and S. aldavei have great potential for Mo(VI) bioremediation. D. pannonicus and S. aldavei can tolerate Na₂MoO₄ up to 1 mg mL^-1 concentrations and the lipid content used in biofuel production was increased during this process.

Keywords: Bioremediation; Chlorophyll-a content; Metal removal; Microalgae; Molybdate.

Fig. 1

The (a) OD750 absorbance, (b) total caretoniod contents of Desmodesmus pannonicus algae under Na₂MoO₄ toxicity for 14 days.

Fig. 2

The (a)chlorophyll-a and (b) chlorophyll-b pigments of Desmodesmus pannonicus algae under Na₂MoO₄ toxicity for 14 days.

Fig. 3

The (a) OD750 absorbance, (b) total caretoniod contents of Scenedesmus aldavei algae under Na₂MoO₄ toxicity for 14 days.

Fig. 4

The (a)chlorophyll-a and (b) chlorophyll-b pigments of Scenedesmus aldavei algae under Na₂MoO₄ toxicity for 14 days.

Fig. 5

The pigment ratios (a) chla/chlb ratio of Desmodesmus pannonicus (b) chla/car ratio of Desmodesmus pannonicus (c) chl/car ratio of Desmodesmus pannonicus.

Fig. 6

The pigment ratios (a) chla/chlb of Scenedesmus aldavei (b) chla/car of Scenedesmus aldavei (c)chl/car of Scenedesmus aldavei.

Fig. 7

The bioremediation of Mo(VI) metals in (a) sample of Desmodesmus pannonicus dried biomass (b) sample from Desmodesmus pannonicus supernatant.

Fig. 8

The bioremediation of Mo(VI) metals in (a) sample of Scenedesmus aldavei dried biomass (b)sample from Scenedesmus aldavei supernatant under Na₂MoO4 toxicity.

Fig. 9

FT-IR spectra of a) Desmodesmus pannonicus control b) Scenedesmus aldavei control c) Desmodesmus pannonicus Na₂MoO4 under teratment d) Scenedesmus aldavei under Na2MoO4 teratment.

Fig. 10

Lipid content of a) Desmodesmus pannonicus b) Scenedesmus aldavei under Na₂ MoO₄ toxicity.