*4.3.9. Single cell protein*

Production of butanol by using fermentation to replace the chemical process depends large‐ ly on the availability of inexpensive and abundant raw materials and efficient bioconversion of these materials. The producers strains of biobutanol which have been extensively studied are *Clostridium sp.* [126, 127] and genetically engineered *E. coli* [129, 130]. Studies to deter‐ mined the recovery of biobutanol from fermentation broth (dry corn and wet corn milling) whey permeate and molasses) by distillation showed that it was not economical when com‐ pared with butanol derived from the current petrochemical route [131]. The use of lignocel‐ lulosic substrates in combination with developed process technologies is expected to make

30 Sustainable Degradation of Lignocellulosic Biomass - Techniques, Applications and Commercialization

2,3-Butanediol (2,3-BDL), also known as 2,3-butylene glycol, is a valuable chemical feed‐ stock because of its application as a solvent, liquid fuel, and as a precursor of many synthet‐ ic polymers and resins. One of its well known applications is the formation of methyl ethyl

Butanediol is produced during oxygen-limited growth, by a fermentative pathway known as the mixed acid-butanediol pathway [133]. The 2,3-BDL pathway and the relative propor‐ tions of acetoin and butanediol serve to maintain the intracellular NAD/NADH balance un‐ der changed culture conditions. All of the sugars commonly found in hemicellulose and cellulose hydrolysates can be converted to butanediol, including glucose, xylose, arabinose, mannose, galactose, and cellobiose. The theoretical maximum yield of butanediol from sug‐ ar is 0.50 kg per kg. With a heating value of 27,200 J/g, 2,3-BDL compares favorably with ethanol (29,100 J/g) and methanol (22,100 J/g) for use as a liquid fuel and fuel additive [134]. Hexose and pentose can be converted to 2,3-BDL by several microorganisms including *Kleb‐ siella* [135], *Aeromonas* [136], *Bacillus* [137], *Paenibacillus* [138], *Serratia*, *Aerobacter* [139] and

The use of plastics is consistently increasing in the society due to its advantages such as low cost and durability, and the replacement of conventional materials such as paper and glass [141]. However, these materials have xenobiotic and recalcitrant nature, having an extreme‐ ly long degradation rate [142, 143]. Besides its slow degradation, the accumulation of plastic is a major risk to marine animals. When is landfilled, is more difficult to occurs the process of decomposition and when it is incinerated, causes the release of several toxic compounds [144]. Due to the increasing demand of plastics and its incorrect disposal, these materials have become a major environmental problem. An alternative to trying to solve this rising problem is the replacement of conventional plastics for biodegradable plastics. Biodegrada‐ ble plastics are natural biopolymers that are synthesized and catabolized by microorganisms and are made from renewable resources and do not lead to the depletion of finite resources [145, 146]. Among bioplastics, polyhydroxyalkanoates (PHA) and polylactates (PLA) got significant attraction. The PHA's are typically accumulated by bacterial via intra or extracel‐ lular while PLA is produced by polymerizing lactic acid via microbial fermentation [147].

the production of biobutanol economically viable [132].

ketone, by dehydration, which can be used as a liquid fuel additive [8].

*4.3.7. Butanediol*

*Enterobacter* [140].

*4.3.8. Biopolymers*

To create a balance between food versus fuel production from lignocellulosic residues, ade‐ quate land use, judicious usage of grain and corn/cane crop residues is essential [153]. Math‐ ews et al. [153] presented a sugarcane 'feed+fuel' biorefinery model, which produces bioethanol and yeast biomass, a source of single-cell protein (SCP), that can be used as a high-protein animal feed supplement. The yeast SCP, which is synthesized as a part of the process of producing cellulosic bioethanol from sugarcane can be used as a supplement for grass in the feed of cattle grazing on pasture and thereby potentially release land for in‐ creased sugarcane production, with minimal land use change effects.

The production of SCP by growing microorganisms on organic wastes and its use in animal feed has a long history. Protein as an animal feed supplement has long been viewed as a potentially very significant development, with much discussion devoted to the topic of mi‐ crobial SCP since the 1970s. The grounds for the intense interest in SCP is that feedstocks, in the form of agricultural and organic wastes are plentiful, and the rate of growth of microor‐ ganisms producing SCP is prodigious. Whereas a soybean crop is harvested after 1 season of growth, microorganisms double their cell mass within hours [154]. According to Tanaka et al. [155] the production of single-cell protein (SCP) from lignocellulosic materials needs four steps: (1) physical and chemical pretreatments; (2) cellulase production; (3) enzymatic hy‐ drolysis; and (4) assimilation or fermentation of holocellulose. For each step the following topics need to be considerate: (1) effect and mode of action of each pretreatment; (2) optimi‐ zation of culture media and operating conditions, and application of mutation, protoplast fusion and gene recombination; (3) elucidation of kinetics of cellulase reaction, and methods of immobilization, stabilization and recovery of cellulases; and (4) examples of SCP produc‐ tion by several types of cultivation and treatment of lignin. According to Zadrazil et al. [156] in order to convert a lignocellulosic material to obtain a more nutritive product, it is necessa‐ ry to choose a microorganism or a microbial complex capable of synthesizing proteins with high nutritional value and, in the case of use of a substrate that has not been subjected to a previous hydrolysis step, able to degrade selectively the lignin present in the substrate. The lignocellulosic wastes can be fermented directly or they can be previously hydrolyzed chem‐ ically. Several reports have shown the application of substrates chemically pre-hydrolyzed for rapid protein enrichment by microbial fermentation. For example, Pessoa et al [157] hy‐ drolyzed sugarcane bagasse using diluted sulphuric acid and the hydrolysate was ferment‐ ed with *Candida tropicalis*. This process resulted in a 31.3% increase in protein content after 5 days of fermentation. However, for non-ruminant animals, which are not able to metabolize the natural fibers that comprise the bulk of lignocellulosic wastes, the bioconversion process must aim to transform these fibers into digestible components such as protein and sugars (mono- and disaccharides) as well as vitamins and minerals.

to BIOEN-FAPESP, CNPq and CAPES, Brazil for the financial assistance to our laboratory to

Bioconversion of Hemicellulose from Sugarcane Biomass Into Sustainable Products

\*Address all correspondence to: silvio@debiq.eel.usp.br and anuj.kumar.chandel@gmail.com

Department of Biotechnology, School of Engineering of Lorena, University of São Paulo,

[1] Chandel AK, Silva SS, Carvalho W, Singh OV. Sugarcane Bagasse and Leaves: Fore‐ seeable Biomass of Biofuel and Bio-products. Journal of Chemical Technology and

[2] Companhia Nacional de Abastecimento. CONAB: Acompanhamento da Safra Brasi‐ leira de Cana-de-açúcar. Primeiro Levantamento-Abril/12. http://www.conab.gov.br.

[3] Pandey A, Soccol CR, Nigam P, Soccol VT. Biotechnological Potential of Agro-indus‐ trial Residues I: Sugarcane Bagasse. Bioresource Technology 2000; 74 69-80.

[4] Krishnan C, Sousa LC, Jin M, Chang L, Dale BE, Balan V. Alkali Based AFEX Pre‐ treatment for the Conversion of Sugarcane Bagasse and Cane Leaf Residues to Etha‐

[5] Soccol CR, Vandenberghe LPS, Medeiros ABP, Karp SG, Buckeridge MS, Ramos LP, Pitarelo AP, Ferreira-Leitão V, Gottschalk LMF, Ferrara MA, Bon EPS, Moraes LMP, Araujo JA, Torres FAG. Bioethanol from Lignocelluloses: Status and Perspectives in

[6] Dias MOS et al. Production of Bioethanol and Other Bio-based Materials from Sugar‐ cane Bagasse: Integration to Conventional Bioethanol Production Process. Chemical

[7] Ojeda K, Avila O, Suarez J, Kafaro V. Evaluation of Technological Alternatives for Process Integration of Sugarcane Bagasse for Sustainable Biofuels Production – Part

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Brazil. Bioresource Technology 2010; 101 4820–4825.

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1. Chemical Engineering Research and Design 2010; 89 270–279.

, Thais Suzane dos Santos Milessi,

http://dx.doi.org/10.5772/53832

33

carry out the research work on various aspects of lignocellulose biotechnology.

Larissa Canilha, Rita de Cássia Lacerda Brambilla Rodrigues, Felipe Antônio Fernandes Antunes, Anuj Kumar Chandel\*

Maria das Graças Almeida Felipe and Silvio Silvério da Silva\*

Biotechnology 2012; 87 11–20.

(accessed 28 May 2012).

**Author details**

Lorena, Brazil

**References**
