(421g) Bioconversion of Laminaria Japonica Using De-Alginate Process As a Pretreatment Strategy

Marine biomass has garnered much attention because it has great potential as a clean and abundance source for producing biofuels. Marine biomass has many advantages over land biomass; (1) it is non-food and abundant source of biofuels, (2) it is easy to cultivate, and (3) it has very low or no lignin. However most of polysaccharide in macroalgae is alginate which is a nonfermentable form of sugar. Alginate is a main component (>40 wt.%) in Laminaria japonica, which is a family of linear polysaccharides distributed widely in the cell walls of algae. The monomers in alginate (alginic acid) - i.e. β-D-mannuronic acid and its C-5 epimer α-L-guluronic acid - can be arranged in varying proportions and sequence in a chain bound by ß-1→4 linkages.

In this study, de-alginate process was developed and optimized for increasing the relative glucan content in fractionated Laminaria japonica prior to bioconversion. In addition to the optimization of the process parameters, the efficient sample size that make dealing easy and catalyst aiming to maximize alginic acid or decomposed product of alginic acid in hydrolyzate were determined. The obtained optimum conditions with sample size of 2.38 ~ 2.83 mm were; sodium carbonate concentration of 6.81%, reaction temperature of 138.7℃, and reaction time of 35 min. After de-alginate process under optimal conditions, the glucan content in Laminaria japonica was increased by approximately three fold from 5.78 to 16.23%. In this paper, various de-alginate conditions are explored and enzyme digestibility are also tested.