Abstract: Prospecting macroalgae (seaweeds) as feedstocks for bioconversion into biofuels and commodity chemical compounds is limited primarily by the availability of tractable microorganisms that can metabolize alginate polysaccharides. Here, we present the discovery of a 36-kilo-base pair DNA fragment from Vibrio splendidus encoding enzymes for alginate transport and metabolism. The genomic integration of this ensemble, together with an engineered system for extracellular alginate depolymerization, generated a microbial platform that can simultaneously degrade, uptake, and metabolize alginate. When further engineered for ethanol synthesis, this platform enables bioethanol production directly from macroalgae via a consolidated process, achieving a titer of 4.7% volume/volume and a yield of 0.281 weight ethanol/weight dry macroalgae (equivalent to ~80% of the maximum theoretical yield from the sugar composition in macroalgae).

Abstract: One of the major challenges in using electrical energy is the efficiency in its storage. Current methods, such as chemical batteries, hydraulic pumping, and water splitting, suffer from low energy density or incompatibility with current transportation infrastructure. Here, we report a method to store electrical energy as chemical energy in higher alcohols, which can be used as liquid transportation fuels. We genetically engineered a lithoautotrophic microorganism, Ralstonia eutropha H16, to produce isobutanol and 3-methyl-1-butanol in an electro-bioreactor using CO(2) as the sole carbon source and electricity as the sole energy input. The process integrates electrochemical formate production and biological CO(2) fixation and higher alcohol synthesis, opening the possibility of electricity-driven bioconversion of CO(2) to commercial chemicals.

Abstract: Depleted supplies of fossil fuel, regular price hikes of gasoline, and environmental damage have necessitated the search for economic and eco-benign alternative of gasoline. Ethanol is produced from food/feed-based substrates (grains, sugars, and molasses), and its application as an energy source does not seem fit for long term due to the increasing fuel, food, feed, and other needs. These concerns have enforced to explore the alternative means of cost competitive and sustainable supply of biofuel. Sugarcane residues, sugarcane bagasse (SB), and straw (SS) could be the ideal feedstock for the second-generation (2G) ethanol production. These raw materials are rich in carbohydrates and renewable and do not compete with food/feed demands. However, the efficient bioconversion of SB/SS (efficient pretreatment technology, depolymerization of cellulose, and fermentation of released sugars) remains challenging to commercialize the cellulosic ethanol. Among the technological challenges, robust pretreatment and development of efficient bioconversion process (implicating suitable ethanol producing strains converting pentose and hexose sugars) have a key role to play. This paper aims to review the compositional profile of SB and SS, pretreatment methods of cane biomass, detoxification methods for the purification of hydrolysates, enzymatic hydrolysis, and the fermentation of released sugars for ethanol production.

Abstract: Bioconversion of agricultural residues for lipase production as well as other value added products would hold a prominent position in future biotechnologies, mainly because of its eco friendliness and flexibility to both developing and developed countries Several residues such as straw, bran, oil cakes, among others attract increasing attention as abundant and cheap renewable feedstock Many researchers considered improvement of substrate composition, physical parameters (temperature, pH, moisture content and particle size), inoculum concentration, and substrate porosity to upgrade and valorize these bioproducts Several species of fungi, yeast and bacteria have been used in utilizing the agricultural residues through fermentation techniques due to their ability to grow on particle surfaces as sources of carbon and energy, and produce important industrial enzymes including lipases This review provides an overview of the present status on the utilization of renewable residues in the form of solid- and liquid-state and their characteristics for production of lipases using different microbial systems

Abstract: Although economically efficient biomass conversion depends on the utilization of the complete cell wall (biorefinery concept), including polysaccharides and lignin, current biofuels research concentrate mostly on cellulose conversion, while lignin is viewed as a side-product that is used primarily as a thermal resource. Microbiological conversion of lignin is almost exclusive to fungi, usually resulting in increased cell mass and lignolytic enzymes. Some bacteria can also degrade lignin-related compounds using the β-ketoadipate pathway; for example, Rhodococcus opacus DSM 1069 can degrade coniferyl alcohol and grow on it as sole carbon source. Moreover, this strain belongs to the actinomycetes group that is also known for oleaginous species with lipid accumulation over 20%. Present work shows that R. opacus DSM 1069 and PD630 strains under nitrogen limiting conditions can convert lignin model compounds into triacylglycerols, also known as neutral lipids. 4-Hydroxybenzoic and vanillic acid lignin model compounds were used as sole carbon sources, and after brief adaptation periods, the cells not only began growing but accumulated lipids to the level of oleaginicity. These lipids were extracted for transesterification and analysis of fatty acid methyl esters showed good composition for biodiesel applications with no aromatics. Furthermore, the two strains showed distinct substrate metabolism and product profiles.

Abstract: List of contributors. Preface. Preface to the first edition. Part One: The principles of bioconversion of waste materials. 1. The enzymic treatment of waste materials P. Gacesa, J. Hubble. 2. Processes with immobilized enzymes and cells S. Dumitriu, E. Chornet. 3. Solid substrate fermentation: a biotechnological approach to bioconversion of wastes O. Paredes-Lopez, S.H. Guzman-Maldonado, A. Alpuche-Solis. 4. Composting processes S.P. Mathur. Part Two: Bioconversion applications. 5. Bioprocessing of agro-residues to value added products V.S. Bisaria. 6. Use of photosynthetic bacteria for the production of SCP and chemicals from organic wastes K. Sasaki, T. Tanka, S. Nagai. 7. Utilization of starch industry wastes S.K. Rakshit. 8. Bioconversion of food processing wastes G.Th. Kroyer. 9. Bioconversion of cheese whey to organic acids R.D. Tyagi, D. Kluepfel. 10. Lignocellulosic wastes: biological conversion P.S. Chahal, D.S. Chahal. 11. Bioconversion of wastewater from the pulp and paper industry K. El Haji, V. Sachdeva, R.D. Tyagi. 12. Fisheries waste biomass: bioconversion alternatives A. M. Martin. 13. Production of Bacillus thuringiensis biopesticides using waste materials M. de Lourdes Tirado Montiel, R.D. Tyagi, J.R. Valero. 14. Biorecovery of metals from mining wastes D.S. Holmes. Index.

Abstract: Summary •There is a pressing global need to reduce the increasing societal reliance on petroleum and to develop a bio-based economy. At the forefront is the need to establish a sustainable, renewable, alternative energy sector. This includes liquid transportation fuel derived from lignocellulosic plant materials. However, one of the current limiting factors restricting the effective and efficient conversion of lignocellulosic residues is the recalcitrance of the substrate to enzymatic conversion. •In an attempt to assess the impact of cell wall lignin on recalcitrance, we subjected poplar trees engineered with altered lignin content and composition to two potential industrial pretreatment regimes, and evaluated the overall efficacy of the bioconversion to ethanol process. •It was apparent that total lignin content has a greater impact than monomer ratio (syringyl : guaiacyl) on both pretreatments. More importantly, low lignin plants showed as much as a 15% improvement in the efficiency of conversion, with near complete hydrolysis of the cellulosic polymer. •Using genomic tools to breed or select for modifications in key cell wall chemical and/or ultrastructural traits can have a profound effect on bioenergy processing. These techniques may therefore offer means to overcome the current obstacles that underpin the recalcitrance of lignocellulosic substrates to bioconversion.

Abstract: With industrial development growing rapidly, there is a need for environmentally sustainable energy sources Ethanol from biomass, bioethanol, is an attractive, sustainable energy fuel source for transportation Based on the premise that fuel bioethanol can contribute to a cleaner environment and with the implementation of environmental protection laws in many countries, demand for this fuel is increasing Efficient ethanol production is based on optimized processes where utilization of cheap substrates is highly demanding Utilization of different types of lignocellulosic materials can be considered for production of ethanol Among various types of lignocellulosic substances water hyacinth (Eichhornia crassipes) is a potential resource available in many tropical regions of the world It is a noxious aquatic weed which grows fast A considerable amount of research work is in progress for its bioconversion into ethanol using two-sequential steps of hydrolysis and fermentation This paper reviews the bioconversion of water hyacinth to ethanol

Abstract: Fermentation of cellulosic and hemicellulosic sugars from biomass could resolve food-versus-fuel conflicts inherent in the bioconversion of grains. However, the inability to coferment glucose and xylose is a major challenge to the economical use of lignocellulose as a feedstock. Simultaneous cofermentation of glucose, xylose, and cellobiose is problematic for most microbes because glucose represses utilization of the other saccharides. Surprisingly, the ascomycetous, beetle-associated yeast Spathaspora passalidarum, which ferments xylose and cellobiose natively, can also coferment these two sugars in the presence of 30 g/liter glucose. S. passalidarum simultaneously assimilates glucose and xylose aerobically, it simultaneously coferments glucose, cellobiose, and xylose with an ethanol yield of 0.42 g/g, and it has a specific ethanol production rate on xylose more than 3 times that of the corresponding rate on glucose. Moreover, an adapted strain of S. passalidarum produced 39 g/liter ethanol with a yield of 0.37 g/g sugars from a hardwood hydrolysate. Metabolome analysis of S. passalidarum before onset and during the fermentations of glucose and xylose showed that the flux of glycolytic intermediates is significantly higher on xylose than on glucose. The high affinity of its xylose reductase activities for NADH and xylose combined with allosteric activation of glycolysis probably accounts in part for its unusual capacities. These features make S. passalidarum very attractive for studying regulatory mechanisms enabling bioconversion of lignocellulosic materials by yeasts.

Abstract: The objective of this study was to evaluate the production of ethanol by Scheffersomyces ( Pichia ) stipitis CBS6054, a native xylose fermenting yeast, from sugars contained in the giant reed ( Arundo donax L.) hemicellulosic hydrolysate. A response surface methodology with two input parameters, severity factor and oxalic acid concentration ranging from 2.87 to 4.05 and from 2 to 8 (% w oxalic acid/w solid dry matter), respectively, was employed to minimize degradation products and maximize sugar release. However, at the optimum condition for sugar release (43.8 g l −1 ), levels of toxic degradation products (acetic acid, furfural, HMF and phenolic compounds) were considered too high for yeast fermentation. The condition to minimize degradation products and maximize sugar yields was judged to be 2.87 severity factor and 5.0% oxalic acid concentration. At this condition 26.0 g l −1 xylose, 5.0 g l −1 glucose and 2.4 g l −1 arabinose were recovered in giant reed hydrolysate fraction. Adjustment of pH to 5.0 with Ca(OH) 2 decreased xylose, glucose and acetic acid, 22%, 8% and 27% respectively. Increasing the initial pH from 5.0 to 5.5, 6.0 and 6.5, respectively, significantly improved the fermentability of the giant reed hemicelluloses hydrolysate; no fermentation was observed at pH 5.0 after 96 h, while 8.20 g l −1 of ethanol was obtained at pH 6.0 after 48 h, with an ethanol yield of 0.33 ( g e / g s ) and a productivity of 0.17 g l −1 h −1 . The optimum pH of acid hydrolysate fermentation for ethanol production was 6.0–6.5.

Abstract: The presence of lignin in lignocellulosic biomass leads to a protective barrier which prevents enzymes from being accessible to cellulose and hemicellulose for hydrolysis. As a result, pre-treatment is a 'must' step for subse- quent enzymatic hydrolysis. Bio pre-treatment is normally conducted at low temperatures and low pressures without using expensive equipment, chemical agents, reactors, and additional energy for lignin removal and biomass struc- ture destruction. Therefore, it is a green, safe, and inexpensive method. White-rot fungi (WRF), a group of fungi (more than 1500 different species) are successfully applied in bioconversion processes such as sewage treatment, biopulp- ing, conversion of forest and agricultural residues to animal feeds, and the production of edible or medicinal mush- rooms. In the bio pre-treatment process, WRF are mostly used for secreting ligninolytic enzymes, a variety of donor substrates and selective degradation of lignin. Current research related to WRF bio pre-treatment is mainly focusing on the following four aspects: (i) selection of candidate strains for certain biomass materials; (ii) optimization of cul- tivation methods; (iii) characterization of fungal treated materials; and (iv) evaluation of combining bio pre-treatment with chemical or physicochemical approaches. Future prospects and recommended research work on applying WRF in bio pre-treatment are also briefl y introduced and summarized in this review. These include (i) integrated methods (i.e. co-treatment with organic solvents, diluted acids, supercritical CO2 and ionic liquids) to resolve problems exist- ing in fungal pre-treatment applications; (ii) mutation breeding and crossbreeding of fungal mycelia to obtain engi- neering strains; and (iii) integration of fungal pre-treatment with simultaneous saccharifi cation and fermentation to produce biofuels and value-added products. © 2012 Society of Chemical Industry and John Wiley & Sons, Ltd

Abstract: The bioconversion of fruit wastes into single cell protein production has the potential to solve the worldwide food protein deficiency by obtaining an economical product for food and feed. Using food processing leftovers in the production of single cell protein as substrate would alleviate pollution. In this work cucumber and orange peels were evaluated for the production of single cell protein using Saccharomyces cerevisiae by submerged fermentation . Results showed that tested fruit wastes were highly susceptible to hydrolysis. A comparative study of fruit wastes revealed that cucumber peel generates higher amount of protein followed by that of orange with 53.4% and 30.5% crude protein respectively per 100 gm of substrate used. Percentage of protein in single cell protein was much lower (17.47%) when Saccharomyces cerevisiae was grown on supplemented fruit hydrolysate medium that contained inorganic nitrogen sources but devoid of glucose. Addition of glucose to the supplemented fruit hydrolysate medium enhanced the protein content (60.31%) within the yeast cell. Thus the single cell protein production by yeast depends on the growth substrates or media composition.

Abstract: Biodiesel has emerged as a potential alternate renewable liquid fuel in the past two decades Total annual production of biodiesel stands at 696 million tons and 112 million tons in USA and Europe, respectively In other countries, Asia and Latin America, biodiesel production has increased at unprecedented rate Despite this, the economy of biodiesel is not attractive An obvious solution for boosting the economy of the biodiesel industry is to look for markets for side products of the transesterification process of biodiesel synthesis The main by-product is glycerol However, this glycerol is contaminated with alkali/acid catalyst and alcohol, and thus, is not useful for conventional applications such as in toothpaste, drugs, paints and cosmetics Conversion of this glycerol to value-added product is a viable solution for effective and economic utilization, which would also generate additional revenue for the biodiesel industry Intensive research has taken place in area of conversion of glycerol to numerous products The conventional catalytic route of glycerol transformation employs prohibitively harsh conditions of temperature and pressure, and thus, has slim potential for large-scale implementation In addition, the selectivity of the process is rather small with formation of many undesired side products The bioconversion processes, on the other hand, are highly selective although with slower kinetics In this review, we have given an assessment and overview of the literature on bioconversion of glycerol We have assessed as many as 23 products from glycerol bioconversion, and have reviewed the literature in terms of microorganism used, mode of fermentation, type of fermentor, yield and productivity of the process and recovery/purification of the products The metabolic pathway of conversion of glycerol to various products has been discussed We have also pondered over economic and engineering issues of large-scale implementation of process and have outlined the constraints and limitations of the process We hope that this review will be a useful source of information for biochemists, biotechnologists, microbiologists and chemical engineers working in the area of glycerol bioconversion

Abstract: α-Arbutin (α-Ab) is a powerful skin whitening agent that blocks epidermal melanin biosynthesis by inhibiting the enzymatic oxidation of tyrosine and l-3,4-dihydroxyphenylalanine (l-DOPA). α-Ab was effectively synthesized from hydroquinone (HQ) by enzymatic biotransformation using amylosucrase (ASase). The ASase gene from Deinococcus geothermalis (DGAS) was expressed and efficiently purified from Escherichia coli using a constitutive expression system. The expressed DGAS was functional and performed a glycosyltransferase reaction using sucrose as a donor and HQ as an acceptor. The presence of a single HQ bioconversion product was confirmed by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). The HQ bioconversion product was isolated by silica gel open column chromatography and its chemical structure determined by 1H and 13 C nuclear magnetic resonance (NMR). The product was determined to be hydroquinone-O-α-d-glucopyranoside with a glucose molecule linked to HQ through an α-glycosidic bond. However, the production yield of the transfer reaction was significantly low (1.3%) due to the instability of HQ in the reaction mixture. The instability of HQ was considerably improved by antioxidant agents, particularly ascorbic acid, implying that HQ is labile to oxidation. A maximum yield of HQ transfer product of 90% was obtained at a 10:1 molar ratio of donor (sucrose) and acceptor (HQ) molecules in the presence of 0.2 mM ascorbic acid.

Abstract: The value-added bioconversion of biomass is necessary due to the depletion of fossil fuels and deterioration of the global environment situation. Based on the analysis of characteristics of solid materials and the applicability of solid agro-industrial residues used as feedstock for solid-state fermentation (SSF), the authors established a value-added bioconversion system for biomass using the key technology SSF. This article gives an overview of biomass bioconversion by SSF and the corresponding advances achieved in recent years. Copyright (c) 2012 Society of Chemical Industry

Abstract: A characteristic of industrial brewing is the production of large quantities of spent grains resulting from the mashing process. This residue is used mainly as animal feed. This study aimed to enzymatically modify the mashing residue by associating an innovative extrusion bioconversion process and compare the effects of the treatments on bread-making. Modification of spent grains with two types of commercial enzymes was evaluated. Bread was made with treated spent grains (TSG) and untreated spent grains (USG), which were later directly added with enzymes in the same concentrations during dough preparation. The bioconversion process modified the structure of arabinoxylans and allowed the formation of water-soluble arabinoxylans. The production of reducing sugars increased, indicating the increase in the production of residual xylose and in the water solubility index. Bread prepared with USG together with the enzymes directly added to the dough had larger specific volume and was softer than that made with TSG. The sensorial preference of the panel did not vary for the different treatments used.