Diatoms and Nualgi - Paper published

A paper on Diatoms based on work by Mr M Thomas Kiran Chief Technology Office of Kadambari Consultants Pvt Ltd is published in Botanica Marina journal - 
http://www.degruyter.com/view/j/botm.2012.55.issue-3/bot-2011-0076/bot-2011-0076.xml

Culture medium optimization and lipid profiling of Cylindrotheca, a lipid- and polyunsaturated fatty acid-rich pennate diatom and potential source of eicosapentaenoic acid

Suman, Keerthi ^1,a / Kiran, Thomas ^1,a / Devi, Uma Koduru ¹ / Sarma, Nittala S. ²

¹Department of Botany, Andhra University, Visakhapatnam 530003, Andhra Pradesh, India

²Department of Marine Chemistry, School of Chemistry, Andhra University, Visakhapatnam 530003, Andhra Pradesh, India

^aThe first two authors made equal contributions to the manuscript.

Corresponding author

Citation Information: . Volume 55, Issue 3, Pages 289–299, ISSN (Online) 1437-4323, ISSN (Print) 0006-8055, DOI: 10.1515/bot-2011-0076, May 2012

Publication History:

Received: 06/08/2011;

Accepted: 28/03/2012;

Published Online: 15/06/2012

Abstract

Cylindrotheca, an epipelic benthic pennate diatom, holds promise as a nutraceutical source and may be useful for aquaculture. Experiments were done on two Cylindrotheca species, Cylindrotheca fusiformis (UTEX 2084) andC. closterium, which was isolated from seawater collected offshore from Visakhapatnam, India. C. closteriumwas identified through microscopy and rDNA typing. Type and concentration of nutrient components in the culture medium that promoted best growth and highest lipid accumulation were identified. Lipid content was gravimetrically estimated. For relative comparison of the effects of different culture media on lipid content, we made estimations through rapid in situ screening method using Nile red staining and spectrofluorimetry. The fatty acid profile of lipid was obtained through gas chromatography-mass spectroscopy. Nualgi, a commercially available micronutrient ready-mix with elements adsorbed as nanoparticles on a modified silica sol, was found to significantly boost growth in bothCylindrotheca species when used in lieu of a conventional micronutrient mix prepared from eight compounds. Among the three nitrogen sources tested – sodium nitrate (NaNO₃), urea, and ammonium chloride (NH₄Cl) – best growth of C. fusiformis occurred on nitrate and urea, while NH₄Cl was best for C. closterium. Lipid productivity was much higher in cultures supplied with NH₄Cl for both Cylindrotheca species and compensated for lower biomass in C. fusiformis. Mixotrophy with glycerol or sodium acetate resulted in no significant increase in growth over photoautotrophy. Both Cylindrothecaspecies were lipid rich; lipid constituted 18–27% of dry biomass in the medium with NaNO₃. Among total fatty acids, polyunsaturated fatty acids constituted <40%, eicosapentaenoic acid 25%, and arachidonic acid ∼8% and ∼4% in C. fusiformis and C. closterium, respectively. NH₄Cl, phosphate, and Nualgi micronutrient ready-mix in concentrations optimal for each strain contribute to a good culture medium for Cylindrotheca.