Utilization of Alginate from Brown Macroalgae for Ethanol Production by Clostridium phytofermentans

Bacterial alginate metabolism: an important pathway for bioconversion of brown algae

“…phaphyphila [ 93 ] and C . phytofermentans [ 120 ]), or detailed metabolic and regulation models for ubiquitous microbes, especially those with the scattered system (e.g. Vibrio [ 7 , 119 ]).…”

“…A1 Engineered strain Alginate N/A 0.26 g g −1 alginate [ 117 ] Vibrio sp. dhg Engineered strain Mannitol, alginate No pretreatment 0.35 g g −1 powder of kelp [ 119 ] Defluviitalea phaphyphila Alg1 Natural strain Mannitol, alginate, laminarin No pretreatment 0.25 g g −1 powder of kelp [ 126 ] Clostridium phytofermentans Natural strain Alginate Acid pretreatment 0.05 g g −1 alginate [ 120 ] …”

“…In addition, this strain has at least two inherent advantages for ethanol production: (i) direct utilisation of pretreated brown algae with a comparatively high ethanol yield of 0.25 g g −1 kelp, and (ii) a thermostable alginolytic system up to 60 °C [ 92 , 93 ]. Recently, the anaerobic Firmicutes strain Clostridium phytofermentans was also found to convert alginate directly from brown algae directly to ethanol [ 120 ]. However, genetic tools have not been developed for these microorganisms.…”

Enhanced Yield of Sodium Alginate Extracted fromPadina gymnosporaUsing a Greener Microwave and Ultrasound Hybrid System

“…This method is generally composed of six steps, namely ethanol/formaldehyde treatment followed by acidification using mineral acids (mainly HCl) as pre-treatments, alkaline extraction with sodium carbonate, solid/liquid separation, precipitation and drying of the alginate powder formed. [5][6][7][8] Even though a dilute acid concentration (typically 0.1-0.2 M) is used for the acid pre-treatment, [6,[9][10][11] inorganic acids are known to be toxic and they present several environmental problems by releasing harmful gases and contributing to the acid rain phenomena. [12] Furthermore, the acid pre-treatment and alkali extraction steps can take up to 24 hours and 2-5 hours respectively, while temperature requirements for successful alginate extraction can reach up to 80-99 °C to attain a maximum extraction yield of 20-40 %, depending on the species and processing conditions used.…”

“…However, the conventional method of alginate extraction, in spite of being fully established on commercial scale, presents several drawbacks. This method is generally composed of six steps, namely ethanol/formaldehyde treatment followed by acidification using mineral acids (mainly HCl) as pre‐treatments, alkaline extraction with sodium carbonate, solid/liquid separation, precipitation and drying of the alginate powder formed [5–8] . Even though a dilute acid concentration (typically 0.1–0.2 M) is used for the acid pre‐treatment, [6,9–11] inorganic acids are known to be toxic and they present several environmental problems by releasing harmful gases and contributing to the acid rain phenomena [12] …”