[For further information on the FAO Biotechnology Forum see the Forum website.
Note, participants are assumed to be speaking on their own behalf, unless they state otherwise.]
Sent: 03 December 2008 09:31
Subject: 52: Biotechnology for bioconversion of lignocellulosics for biofuel production
This is Anju Arora from the Indian Agricultural Research Institute, N.Delhi, India.
I appreciate the initiative taken by FAO to stimulate this discussion and have been following the messages. But I feel not much has been said about actual biotechnology for making biofuels a viable option.
We have been working on getting fermentable sugars from lignocellulosics including agro-residues, forestry residues and food processing wastes. There are processes described for production of cellulases as well as Simultaneous Saccharification and Fermentation (SSF) and also using genetically engineered organisms for SSF. But I wish to know if these processes have been used on an industrial scale. In the past I have read about genetically engineered strain of E. coli being used for bioconversion of lignocellulosics by some private company in Canada for production of bioethanol.
I am from a developing country where food as well as fuel are big concerns. If we use agricultural and forestry waste for biofuel production, it will be useful in management of crop residues also. People are working on different aspects of this process, as highlighted in the background document, like production of cellulases and making the pretreatment and hydrolysis of polysaccharides a more economical and feasible process. I look forward to any suggestions/breakthroughs/approaches in this regards for conversion of lignocellulosics into fermentable sugars. Definitely I feel all the participants will be happy to get a response from developed countries in this area for development of a viable process for lignocellulose bioconversion.
Division of Microbiology,
Indian Agricultural Research Institute,
anjudev (at) yahoo.com
[Section 3.2c of the Background Document to the conference gives a 2-page overview of conversion of lignocellulosic biomass to liquid biofuels, including definition of SSF etc. The document is available at http://www.fao.org/biotech/C15doc.htm or contact me at firstname.lastname@example.org if you want to receive it within an e-mail or as a PDF or WORD attachment....Moderator].
Sent: 03 December 2008 10:52
Subject: 53: Re: Biotechnology and ethanol from sorghum
This is from Ismail Dweikat, University of Nebraska, United States.
Sweet sorghum is an ideal bioenergy crop. It is a very drought tolerant crop with half the cost of corn to grow. With some varieties like Wray, we were able to produce about 10 metric tons of sugar/ha. Also, we have incorporated the brown midrib genes (bmr 6 and 12) into many of our lines and hybrids in an effort to enhance both the digestibility (as animal food) and sugar extraction from the stems. We are in the process of introducing the sucrose isomerase gene into sweet sorghum in order to hopefully double the amount of extractable available sugar as similar work has been accomplished with sugarcane.
Sorghum/Pearl Millet Genetics
279 Plant Sciences
Agronomy and Horticulture Dept.
University of Nebraska, Lincoln, NE 68583
Ph. 402 472 5328
email: idweikat2 (at) unl.edu
[Mutations in brown midrib genes can change cell wall composition by reducing lignin and other attributes. Also, researchers in Australia have found that introducing a bacterial gene encoding sucrose isomerase to sugarcane can greatly boost its sugar yields. See below for more information on these two issues:
"Breeders are renewing an interest in sweet (stemmed) sorghums and maize, which are similar in sugar content (but not composition) as sugar cane, as speciality crops for bioethanol production. The sugar and mineral content of the syrups rendered these not amenable to production of crystalline sugar (sucrose), but this is inconsequential for bioethanol production. Breeders have endeavored to breed higher straw digestibility within the limited variability of the genomes of the various crops. Brown mid-rib (bmr) mutations in maize and sorghum have been isolated that have a lower lignin content and much higher digestibility. They have been used to breed forage (silage) maize and sorghum, invariably with somewhat lower yields, which can be economically compensated for by the greater digestibility. The brown midribs are due to mutations in lignin biosynthesis, which lead to slightly less lignin as well as a modified lignin sub-unit composition". (from J. Gressel. 2008 Transgenics are imperative for biofuel crops. Plant Science 174: 246-263).
"Sucrose is the feedstock for more than half of the world's fuel ethanol production and a major human food. It is harvested primarily from sugarcane and beet. Despite attempts through conventional and molecular breeding, the stored sugar concentration in elite sugarcane cultivars has not been increased for several decades. Recently, genes have been cloned for bacterial isomerase enzymes that convert sucrose into sugars which are not metabolized by plants, but which are digested by humans, with health benefits over sucrose. We hypothesized that an appropriate sucrose isomerase (SI) expression pattern might simultaneously provide a valuable source of beneficial sugars and overcome the sugar yield ceiling in plants. The introduction of an SI gene tailored for vacuolar compartmentation resulted in sugarcane lines with remarkable increases in total stored sugar levels. The high-value sugar isomaltulose was accumulated in storage tissues without any decrease in stored sucrose concentration, resulting in up to doubled total sugar concentrations in harvested juice. The lines with enhanced sugar accumulation also showed increased photosynthesis, sucrose transport and sink strength. This remarkable step above the former ceiling in stored sugar concentration provides a new perspective into plant source-sink relationships, and has substantial potential for enhanced food and biofuel production". (abstract of Wu, L.G. and Birch, R.G. (2007) Doubled sugar content in sugarcane plants modified to produce a sucrose isomer. Plant Biotechnology Journal 5: 109-117)...Moderator].
Sent: 03 December 2008 10:53
Subject: 54: Re: Biotechnology and ethanol from sorghum
This is from Sergio Eduardo Contreras. I am an agronomist, with an M.Sc. in plant breeding from the Universidad Nacional Agraria La Molina, Peru. At present, I am professor of plant breeding at the Universidad Nacional Jose Faustino Sanchez Carrion, Huacho, Peru (www.unjfsc.edu.pe). I was reading all the presentations and comments and they are very interesting for my classes and professional work. Thank you very much for this opportunity.
Responding to message 43 of M.J. Vasudeva Rao: My greetings for your work in sorghum for ethanol production. I have noticed that University of Arizona in Tucson are looking for new genotypes for sugar and ethanol. Maybe you can contact them.
Sergio Contreras Liza
Calle El Galeon 136, Surco Lima 33
Telefonos: 232 1918 (FAX) - 232 2773 (TRABAJO)
e-mail: sergio_cl2002 (at) yahoo.com
Sent: 03 December 2008 12:26
Subject: 55: Re: Biotechnology for bioconversion of lignocellulosics for biofuel production
This message is from Jan Jansa, based at ETH (Federal Institute of Technology) in Zurich, Switzerland. I am working on nutrient and carbon fluxes between soil and plants, with particular attention to soil microorganisms.
As to my theoretical knowledge and lab experience, degradation of lignin and cellulose are extremely inefficient processes and current efforts to improve both the rate and efficiency of degradation of these biopolymers are not really successful. At best, you can convert few percent of the biomass to fermentable sugars within a scale of several to many days. Economically, it will not pay off at any near future, certainly not as early as we need it - unless there is some unexpected break-through, which cannot really be planned. After all, these compounds were selected through eons of evolution to withstand enzymatic degradation, we shall not be so blind to ignore the nature. If any, these compounds shall be burnt and converted to electricity/hydrogen or other energy carriers as needed, or the heat used directly. I am not a fan of producing gas carriers (either hydrogen or methane) for long-distance transport, it is certainly safer to move the wood around as compared to liquefied methane or hydrogen. Apart from the technical issues above, a worry I have about using plant biomass/residues for energy production is that their removal from the fields can have important consequences for the ecosystem (soil erosion etc.).
Dr. Jan Jansa
Institute of Plant Sciences
CH - 8315 Lindau (ZH)
email: jan.jansa (at) ipw.agrl.ethz.ch