Utilization of alginate from brown macroalgae for ethanol production by Clostridium phytofermentans 1 Dharshini , A. Aliya
1 Fathima ,
1 Dharani ,
1* Ramya
R. Siva S.Renuka M. 1. Molecular Genetics Lab, Department of Genetic Engineering, School of Bioengineering, SRM Institute of Science and Technology, Kattankulathur, Kancheepuram District, Tamil Nadu, India 603203 Results
Abstract
Table 1. Carbohydrate composition of Padina tetrastromatica and Turbinaria ornate
Brown macroalgae have been characterized as a potential feedstock for bioethanol production. The bioconversion of brown macroalgae requires investigation on microbial strains that can convert alginate into bioethanol. In this study, we have shown the ability of Clostridium phytofermentans to utilize the alginate extracted from brown macroalgae for ethanol production. Fermentation studies were performed with alginate extracts of two brown macroalgae Padina tetrastromatica and Turbinaria ornata. The ethanol concentration achieved by batch fermentation was 0.952 g/L with synthetic sodium alginate, 0.375 g/L with alginate extract of Padina tetrastromatica and 1.0 g/L with alginate extract of Turbinaria ornata.
Macroalgae Used
Total soluble sugars (mg/g) Padina 78.77 ± tetrastromatica 1.22 Turbinaria ornata 60.10 ± 3.91
a
Xylan (mg/g)
187 ± 6.68
59.9 ± 1.3
57.1±1.72
300 ± 6.32
65.1± 1.2
51.5±1.66
d
b
e
%T
c
Figure S1. Microscopic analysis of C. phytofermentans grown on synthetic sodium alginate media. (a) SYTO9 stained sample without C. phytofermentans; (b) and (c) SYTO9 stained samples with C. phytofermentans after 24 h and 48 h respectively; (d) SEM image of sodium alginate without C. phytofermentans (e) SEM image of clearance of sodium alginate with C. phytofermentans after 120 h.
The C. phytofermentans an anaerobic, mesophilic and ethanol-producing bacteria reported in this study has remarkable feature of having diverse carbohydrate-active enzymes in its genome (http://www.cazy.org/) for the utilization of a wide range of polysaccharides (Lombard et al. 2014, Tolonen et al. 2015). The presence of alginate lyases, oligo-alginate lyases, and well-characterized glycoside hydrolases (Boutard et al. 2014) in C. phytofermentans makes this organism suitable for direct conversion of alginate into ethanol. In the current study, fermentation studies were carried out to study the ability of C. phytofermentans to utilize alginate extracted from brown macroalgae for ethanol production. This is the first study in this context to utilize natural isolate for alginate fermentation without pretreatment.
B
Wavenumber (cm-1)
Figure 1. FTIR spectrum for seaweed alginate. Alginate extracted from Padina tetrastromatica (A); Alginate extracted from Turbinaria ornata (B). T-Transmittance.
T o ta l P r o te in C o n te n t (m g /m L )
s o d iu m a lg in a te ( A ) a lg in a te fr o m P a d in a te tr a s to m a tic a ( B )
10
a lg in a te fr o m T u r b in a r ia o r n a ta ( C )
5
0 0
2
4
4
8
7
2
9
6 1
2
0 1
4
4
e (h ) Figure 2. GrowthT imanalysis in GS2 fermentation media. Synthetic sodium alginate (A); Alginate extracted from Padina tetrastromatica (A); Alginate extracted from Turbinaria ornata (B) as carbon sources.
Figure 3. Ethanol production. Synthetic sodium alginate (A); Alginate extracted from Padina tetrastromatica (A); Alginate extracted from Turbinaria ornata (B) as carbon sources.
Conclusion
Methodology ➢ Clostridium phytofermentans strains and culture media (GS2 media) ➢ Macroalgal species like Padina tetrastromatica, Turbinaria ➢ Phrase contrast microscopy and FTIR
Cellulose (mg/g)
A
Introduction
ornata
Alginate (mg/g)
Alginate metabolism in C. phytofermentans needs to be understood more deeply when it comes to efficient conversion of macroalgal biomass into bioethanol. The results in the present study highlight the ability of C. phytofermentans to utilize alginate extracted from brown macroalgae to produce ethanol. Consequently, the ethanol titers can be further increased by optimization of fermentation experiments with whole brown algal biomass.
➢ Gas chromatography
Acknowledgement The authors acknowledge the SRM Institute of Science and Technology, India for providing infrastructure facilities.
References ➢ Petit, E., M.V. Coppi, J.C. Hayes, A.C. Tolonen, T. Warnick, W.G. Latouf, D. Amisano, A. Biddle, S. Mukherjee, N. Ivanova, and A. Lykidis. (2015). Genome and transcriptome of Clostridium phytofermentans, catalyst for the direct conversion 6of plant feedstocks to fuels. PloS one 10 6:e0118285, doi:10.1371/journal.pone.0118285. ➢ Lombard, V., H.G. Ramulu, E. Drula, P.M. Coutinho, and B. Henrissat. (2014). The carbohydrate-active enzymes database (CAZy) in 2013. Nucleic Acids Research, 42, D490-D495. doi: 10.1093/nar/gkt1178.