Screening And Characterization Of Starch Produced From Marine Microalgae Klebsormidium Flaccidum Gn-2

Loading...
Thumbnail Image
Date
2021-03
Authors
Ramli, Rozi Nuraika
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Starch is the main component that belongs to two third of the human diet pyramid and another one third of starch is used in non-food applications such as biofuel and bioplastic. Products produced from starch are biodegradable and help in reducing the environment pollution. However, environmental problem such as deforestation and shortage of food will eventually happen if the demands of starch from non-food and food products increase. Simultaneously, crops using as feedstocks for biofuel will result in food versus fuel implication. To resolve this problem, the attentions of researchers have been driven towards microalgae. The easy growing and environmentally friendly microalgae has opened a new potential of revolution for starch-based product. In this research two strains of marine microalgae have been successfully isolated and screened from Penang Sea. Based on morphological and molecular identification, these 2 strains are designated as Klebsormidium flaccidum GN-2 and Nannochloropsis oculata YG-2. K. flaccidum GN-2 produced 16.84% of starch and 0.81 g/L biomass while, N. oculata YG-2 produced 3.06% and 0.40 g/L ofstarch and biomass, respectively. Microalgae K. flaccidum GN-2 was chosen for optimization using Response Surface Methodology (RSM) to increase production of starch since it yield higher starch than Nannochloropsis oculata YG-2. The starch produced was 19.06% under the optimized conditions of 35.53 ppt salinity, 23 hours of light exposure and flow rate of 1 v/v of carbon dioxide. The nutrient optimization was studied based on depletion of nitrogen (N), phosphorus (P) and iron (Fe) as the nutrient depletion will change the physiochemical of the microalgae. Decreasing of biomass (N = 0.98 g/L, P = 0.22 g/L and Fe = 0.24 g/L) and starch (N = 6.39%, P = 4.62%, Fe = 4.46%) however illustrated that depletion of the nutrients in K. flaccidum GN-2 could not increase the starch content. The starch was characterized and compared with commercial corn starch (CCS) for its properties. Small granule (1 μm) and high amylose content (25.52%) in K. flaccidum GN-2 were compared to commercial corn starch (size 7 μm, amylose 23.04%) suggested that starch from K. flaccidum GN-2 as the best potential feedstock for strong and stiffer films due to small size of granule. Gelatinization of starch from K. flaccidum GN-2 is lower (ΔHgel = 9.45 J/g) than commercial corn starch (ΔHgel = 11.63 J/g). This is due to the lower amylopectin content in K. flaccidum GN-2 leads to lower crystallinity and less energy needed to dissociate the molecule within the granule. The retrogradation and syneresis results showed that microalgae starch contains similar stability with CCS as the gelatinized starch able to reassociate to form more ordered structure within 72 hours and completely ageing after 3rd cycle like CCS. In conclusion, marine microalgae isolated from Penang Sea was successfully produced starch. Even though the optimized starch did not show significant increased, however the characteristics studied in starch from K. flaccidum GN-2 is comparable to the CCS starch. Hence it could be an alternative to produce various sustainable products that least compete with crops starch.
Description
Keywords
Technology
Citation