Navigation Links
Trained bacteria convert bio-wastes into plastic
Date:11/19/2010

Researcher Jean-Paul Meijnen has 'trained' bacteria to convert all the main sugars in vegetable, fruit and garden waste efficiently into high-quality environmentally friendly products such as bioplastics. He will be defending his doctoral thesis on this topic, which was carried out in the context of the NWO B-Basic programme, at TU Delft in the Netherlands on Monday 22 November 2010.

There is considerable interest in bioplastics nowadays. The technical problems associated with turning potato peel into sunglasses, or cane sugar into car bumpers, have already been solved. The current methods, however, are not very efficient: only a small percentage of the sugars can be converted into valuable products. By adapting the eating pattern of bacteria and subsequently training them, Meijnen has succeeded in converting sugars in processable materials, so that no bio-waste is wasted.

The favoured raw materials for such processes are biological wastes left over from food production. Lignocellulose, the complex combination of lignin and cellulose present in the stalks and leaves of plants that gives them their rigidity, is such a material. Hydrolysis of lignocellulose breaks down the long sugar chains that form the backbone of this material, releasing the individual sugar molecules. These sugar molecules can be further processed by bacteria and other micro-organisms to form chemicals that can be used as the basis for bioplastics. The fruit of the plant, such as maize, can be consumed as food, while the unused waste such as lignocellulose forms the raw material for bioplastics.

Cutting the price of the process

'Unfortunately, the production of plastics from bio-wastes is still quite an expensive process, because the waste material is not fully utilized,' explains Jean-Paul Meijnen. (It should be noted here that we are talking about agricultural bio-wastes in this context, not the garden waste recycled by households.) The pre-treatment of these bio-wastes leads to the production of various types of sugars such as glucose, xylose and arabinose. These three together make up about eighty per cent of the sugars in bio-waste.

The problem is that the bacteria Meijnen was working with, Pseudomonas putida S12, can only digest glucose but not xylose or arabinose. As a result, a quarter of the eighty per cent remains unused. 'A logical way of reducing the cost price of bioplastics is thus to 'teach' the bacteria to digest xylose and arabinose too.'

Enzymes

The xylose has to be 'prepared' before Pseudomonas putida S12 can digest it. This is done with the aid of certain enzymes. The bacteria are genetically modified by inserting specific DNA fragments in the cell; this enables them to produce enzymes that assist in the conversion of xylose into a molecule that the bacteria can deal with.

Meijnen achieved this by introducing two genes from another bacterium (E. coli) which code for two enzymes that enable xylose to be converted in a two-stage process into a molecule that P. putida S12 can digest.

Evolution

This method did work, but not very efficiently: only twenty per cent of the xylose present was digested. The modified bacteria were therefore 'trained' to digest more xylose. Meijnen did this by subjecting the bacteria to an evolutionary process, successively selecting the bacteria that showed the best performance.

'After three months of this improvement process, the bacteria could quickly digest all the xylose present in the medium. And surprisingly enough, these trained bacteria could also digest arabinose, and were thus capable of dealing with the three principal sugars in bio-wastes.'

Meijnen also incorporated other genes, from the bacterium Caulobacter crescentus. This procedure also proved effective and efficient from the start.

Blend

Finally, in a separate project Meijnen succeeded in modifying a strain of Pseudomonas putida S12 that had previously been modified to produce para-hydroxybenzoate (pHB), a member of the class of chemicals known as parabens that are widely used as preservatives in the cosmetics and pharmaceutical industries.

Meijnen tested the ability of these bacteria to produce pHB, a biochemical substance, from xylose and from other sources such as glucose and glycerol. He summarized his results as follows: 'This strategy also proved successful, allowing us to make biochemical substances such as pHB from glucose, glycerol and xylose. In fact, the use of mixtures of glucose and xylose, or glycerol and xylose, gives better pHB production than the use of unmixed starting materials. This means that giving the bacteria pretreated bio-wastes as starting material stimulates them to make even more pHB.'


'/>"/>

Contact: Ineke Boneschansker
i.boneschansker@tudelft.nl
31-152-788-499
Delft University of Technology
Source:Eurekalert  

Related biology news :

1. Strained quantum dots show new optical properties
2. Bacteria use toxic darts to disable each other, according to UCSB scientists
3. Army-funded technology detects bacteria in water
4. Researchers unlock the secret of bacterias immune system
5. New sensor derived from frogs may help fight bacteria and save wildlife
6. Bacteria gauge cold with molecular measuring stick
7. TYRX AIGISRx antibacterial envelope shows low infection rate, high CIED procedure success
8. NIH-funded scientists sequence genomes of lyme disease bacteria
9. Key difference in how TB bacteria degrade doomed proteins
10. Gambling on bacteria
11. UCLA-led research team finds that bacteria can stand up and walk
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Trained bacteria convert bio-wastes into plastic
(Date:4/5/2017)... NEW YORK , April 5, 2017 ... security, is announcing that the server component of the ... is known for providing the end-to-end security architecture that ... customers. HYPR has already secured over 15 ... system makers including manufacturers of connected home product suites ...
(Date:3/30/2017)... ANGELES , March 30, 2017  On April ... Hack the Genome hackathon at Microsoft,s ... exciting two-day competition will focus on developing health and ... Hack the Genome is the ... been tremendous. The world,s largest companies in the genomics, ...
(Date:3/28/2017)... 2017 The report "Video Surveillance ... Servers, Storage Devices), Software (Video Analytics, VMS), and Service ... Forecast to 2022", published by MarketsandMarkets, the market was ... projected to reach USD 75.64 Billion by 2022, at ... base year considered for the study is 2016 and ...
Breaking Biology News(10 mins):
(Date:6/20/2017)... ... June 20, 2017 , ... ... the adulterants which pose the most likely threat to their products at the ... year. , IFT's annual food expo attracts over 20,000 attendees representing food ...
(Date:6/20/2017)... South San Francisco, CA (PRWEB) , ... June ... ... company with patented technology for discovery of antibody therapeutics from millions-diverse immune repertoires, ... 2017 International Conference in San Diego, California. Dave Johnson, PhD, CEO of GigaGen, ...
(Date:6/19/2017)... ... ... A colony of healthy honey bees is like a superorganism--individual bees provide the ... nutrients necessary for growth and survival. Better nutrition gives the colony a strong immune ... decline in honey bee health. Sick and weakened bees diminish the colony's resiliency, leading ...
(Date:6/15/2017)... ... June 15, 2017 , ... New resistant soybean ... options for managing Palmer amaranth and other broadleaf weeds resistant to glyphosate. But ... necessary. Auxin herbicides are known to drift and to cause harm to sensitive, ...
Breaking Biology Technology: