Chemical analysis and biorefinery of red algae Kappaphycus alvarezii for efficient production of glucose from residue of carrageenan extraction process

Abstract

BackgroundBiorefineries serve to efficiently utilize biomass and their by-products. Algal biorefineries are designed to generate bioproducts for commercial use. Due to the high carbohydrate content of algal biomass, biorefinery to generate biofuels, such as bioethanol, is of great interest. Carrageenan is a predominant polysaccharide hydrocolloid found in red macroalgae and is widely used in food, cosmetics, and pharmaceuticals. In this study, we report the biorefinery of carrageenan derived from processing of experimental strains of the red macroalgae Kappaphycus alvarezii. Specifically, the chemical composition and enzymatic hydrolysis of the residue produced from carrageenan extraction were evaluated to determine the conditions for efficient generation of carbohydrate bioproducts.ResultsThe productivity and growth rates of K. alvarezii strains were assessed along with the chemical composition (total carbohydrates, ash, sulfate groups, proteins, insoluble aromatics, galacturonic acid, and lipids) of each strain. Two strains, brown and red, were selected based on their high growth rates and productivity and were treated with 6 % KOH for extraction of carrageenan. The yields of biomass from treatment with 6 % KOH solution of the brown and red strains were 89.3 and 89.5 %, respectively. The yields of carrageenan and its residue were 63.5 and 23 %, respectively, for the brown strain and 60 and 27.8 %, respectively, for the red strain. The residues from the brown and red strains were assessed to detect any potential bioproducts. The galactan, ash, protein, insoluble aromatics, and sulfate groups of the residue were reduced to comparable extents for the two strains. However, KOH treatment did not reduce the content of glucan in the residue from either strain. Glucose was produced by enzymatic hydrolysis for 72 h using both strains. The glucan conversion was 100 % for both strains, and the concentrations of glucose from the brown and red strains were 13.7 and 11.5 g L−1, respectively. The present results highlight the efficiency of generating a key bioproduct from carrageenan residue.ConclusionsThis study demonstrates the potential for glucose production using carrageenan residue. Thus, the biorefinery of K. alvarezii can be exploited not only to produce carrageenan, but also to generate glucose for future use in biofuel production.

Can Seaweed Farming Play a Role in Climate Change Mitigation and Adaptation?

“…Algal biorefineries have evolved from concept and laboratory tests to pilot-scale plants involving a range of seaweed species and environments (e.g., Baghel et al, 2014;Lorbeer et al, 2015;Bikker et al, 2016;Masarin et al, 2016), and may soon become commercial operations. The range of potential products also include using the nutrient-rich residues from a biofuel production for fertilizer, which may also serve for C retention in soil (Seghetta et al, 2016).…”

Avalição Do Conteúdo De Proteínas E Grupos Sulfatos Presentes Em Diferentes Frações Da Macroalga Kappaphycus Alvarezii

“…Os rendimentos obtidos em cada uma dessas etapas foram reportados na literatura recente (Masarin et al, 2016). Para a determinação dos conteúdos de proteínas pelos métodos de Lowry, Kieldahl e Análise elementar as amostras foram previamente moídas em moinho de (Masarin et al 2016), porém foi utilizado um fator de 4.92 para a determinação dos teores de proteínas (Lourenço et al 2002). Para o método de Lorwy, 200 mg das amostras foram pesadas em tubos de ensaios e tratadas com NaOH 1M a 70°C por 4h para dissolver as proteínas (Hartree,1972).…”

“…Para a determinação de grupos sulfatos foram utilizados dois métodos (Espectrofotométrico e Análise Elementar). O método espectrofotométrico foi realizado segundo reportado na literatura recente (Masarin et al, 2016). O método de Análise elementar para determinação do conteúdo de grupos sulfato utilizou a mesma técnica de determinação de proteínas, porém foi determinado o valor total de átomos de enxofre, que foi utilizado para o cálculo de grupos sulfatos (Masarin et al, 2016).…”

PRODUCTION OF CARRAGEENAN BY DIFFERENT STRAINS OF Kappaphycus alvarezii CULTIVATED IN SERANG, INDONESIA

“…K. alvarezii has several strains that are distinguished mainly because of the difference in their color. It is the main source of kappa-carrageenan, a hydrocolloid that has been used extensively as an additive in various industries such as food, cosmetics, and pharmaceutical industries [2,3]. Carrageenan is a linear sulfated polysaccharide made up of a repeating disaccharide sequence of α-D-galactopyranose linked 1,3 called the A residue and β-D-galactopyranose residues linked through positions 1,4 (B residues) that can be extracted from K. alvarezii [4].…”