Cyanobacterial biomass was hydrolyzed using a simple enzymatic treatment and fermented into ethanol

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1 Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark
The electronic version of this article is the complete one and can be found online at: http://www.biotechnologyforbiofuels.com/content/7/1/64 Received: 6 November 2013 Accepted: 27 March 2014 Published: 17 April 2014
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0 ), which permits honeywell humidifier unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. honeywell humidifier The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies honeywell humidifier to the data made available in this article, unless otherwise stated.
Microbial bioconversion of photosynthetic biomass is a promising approach to the generation of biofuels and other bioproducts. However, rapid, high-yield, and simple processes are essential for successful applications. Here, biomass from the rapidly growing photosynthetic marine cyanobacterium Synechococcus sp. PCC 7002 was fermented using yeast into bioethanol. Results
The cyanobacterium accumulated a total carbohydrate content of about 60% of cell dry weight when cultivated under nitrate limitation. The cyanobacterial cells were harvested by centrifugation and subjected to enzymatic hydrolysis using lysozyme honeywell humidifier and two alpha-glucanases. This enzymatic hydrolysate was fermented into ethanol by Saccharomyces cerevisiae without further treatment. All enzyme treatments and fermentations honeywell humidifier were carried out in the residual growth medium of the cyanobacteria with the only modification being that pH was adjusted to the optimal value. The highest ethanol yield and concentration obtained was 0.27 g ethanol per g cell dry weight and 30 g ethanol L -1 , respectively. About 90% of the glucose in the biomass was converted to ethanol. The cyanobacterial hydrolysate was rapidly honeywell humidifier fermented (up to 20 g ethanol L -1  day -1 ) even in the absence of any other nutrient additions to the fermentation medium. Conclusions
Cyanobacterial biomass was hydrolyzed using a simple enzymatic treatment and fermented into ethanol more rapidly and to higher concentrations than previously reported for similar honeywell humidifier approaches using cyanobacteria or microalgae. Importantly, as well as fermentable carbohydrates, the cyanobacterial hydrolysate contained additional nutrients that promoted fermentation. This hydrolysate is therefore a promising substitute for the relatively expensive honeywell humidifier nutrient additives (such as yeast extract) commonly used for Saccharomyces fermentations. Keywords: Cyanobacteria; Bioethanol; Microalgae; Saccharomyces ; Yeast extract Background
Photosynthetic biomass is a promising resource for the generation of biofuels and other valuable bioproducts. However, rapid biomass production and high-yield conversion processes honeywell humidifier are essential for successful applications. Plant-derived lignocellulosic biomass is abundant but, due to the recalcitrant nature honeywell humidifier of this material, significant challenges have to be solved if this biomass is to be used for the microbial honeywell humidifier production of biofuels and bioproducts [ 1 - 3 ]. Photosynthetic microorganisms constitute an appealing alternative source of biomass honeywell humidifier for many reasons. Photosynthetic microorganisms grow much faster than terrestrial plants, have a higher efficiency in using the energy of light, and can be cultivated in areas and in a manner that do not compete with plant-based food and feed production [ 4 - 7 ]. In this context, marine photosynthetic microorganisms have a distinct advantage in large-scale cultivation as they can be cultivated in sea water, which is not suitable for human consumption and most agricultural uses.
The most abundant photosynthetic microorganisms in nature are cyanobacteria and certain eukaryotic microalgae, including green algae, red algae, and diatoms [ 8 ]. Despite their plant-like photosynthesis, honeywell humidifier the evolutionary origins honeywell humidifier and cellular properties of these microorganisms are very diverse. Cyanobacteria produce a wealth of high-value bioproducts and have been mass-cultivated for centuries as a nutritional supplement [ 9 ]. Currently, honeywell humidifier much effort is being put into the genetic and metabolic engineering honeywell humidifier of photosynthetic microorganisms, especially cyanobacteria, for the production of bioproducts not naturally produced by these organisms [ 10 , 11 ]. However, the direct use of biomass from cyanobacteria and other microalgae as a