MSGID: 1:317/3 63e1d3e8   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    How waste-eating bacteria digest complex carbons    
    New information could lead to bacteria-based platforms that recycle   
   plastic and plant waste    
      
     Date:   
         February 6, 2023   
     Source:   
         Northwestern University   
     Summary:   
         For the first time, researchers mapped the metabolic mechanisms   
         in a Comamonas bacterium that digests chemicals from plastic and   
         plant waste.   
      
         This new information could potentially lead to novel biotechnology   
         platforms that harness the bacteria to help recycle plastic waste.   
      
      
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   FULL STORY   
   ==========================================================================   
   A common environmental bacterium, Comamonas testosteroni, could someday   
   become nature's plastic recycling center. While most bacteria prefer to   
   eat sugars, C.   
      
   testosteroni, instead, has a natural appetite for complex waste from   
   plants and plastics.   
      
      
   ==========================================================================   
   In a new Northwestern University-led study, researchers have,   
   for the first time, deciphered the metabolic mechanisms that enable   
   C. testosteroni to digest the seemingly undigestible. This new information   
   could potentially lead to novel biotechnology platforms that harness   
   the bacteria to help recycle plastic waste.   
      
   The research will be published on Feb. 6 in the journal Nature Chemical   
   Biology.   
      
   Comamonas species are found nearly everywhere -- including in soils and   
   sewage sludge. C. testosteroni first caught researchers' attention with   
   its natural ability to digest synthetic laundry detergents. After further   
   analysis, scientists discovered that this natural bacterium also breaks   
   down compounds from plastic and lignin (fibrous, woody waste from plants).   
      
   Although other researchers have worked to engineer bacteria that   
   can breakdown plastic waste, Aristilde believes bacteria with natural   
   abilities to digest plastics hold more promise for large-scale recycling   
   applications.   
      
   "Soil bacteria provide an untapped, underexplored, naturally occurring   
   resource of biochemical reactions that could be exploited to help us deal   
   with the accumulating waste on our planet," said Northwestern's Ludmilla   
   Aristilde. "We found that the metabolism of C. testosteroni is regulated   
   on different levels, and those levels are integrated. The power of   
   microbiology is amazing and could play an important role in establishing a   
   circular economy."  The study was led by Aristilde, an associate professor   
   of civil and environmental engineering at Northwestern's McCormick School   
   of Engineering, and Ph.D. student Rebecca Wilkes, who is the paper's   
   first author. The study included collaborators from University of Chicago,   
   Oak Ridge National Laboratory and Technical University of Denmark.   
      
   Kicking sugar Most projects to engineer bacteria involve Escherichia Coli   
   because it is the most well-studied bacterial model organism. But E. Coli,   
   in its natural state, readily consumes various forms of sugar. As long   
   as sugar is available, E. Coli will consume that -- and leave the plastic   
   chemicals behind.   
      
   "Engineering bacteria for different purposes is a laborious process,"   
   Aristilde said. "It is important to note that C. testosteroni cannot   
   use sugars, period.   
      
   It has natural genetic limitations that prevent competition with sugars,   
   making this bacterium an attractive platform."  What C. testosteroni   
   really wants, though, is a different source of carbon. And materials   
   such as plastic and lignin contain compounds with a ring of tasty carbon   
   atoms. While researchers have known that C. testosteronican digest these   
   compounds, Aristilde and her team wanted to know how.   
      
   "These are carbon compounds with complex bond chemistry," Aristilde   
   said. "Many bacteria have great difficulty breaking them apart."   
   Combining different 'omics' To study how C. testosteroni degrades these   
   complex forms of carbon, Aristilde and her team combined multiple forms   
   of "omics"-based analyses: transcriptomics (study of RNA molecules);   
   proteomics (study of proteins); metabolomics (study of metabolites); and   
   fluxomics (study of metabolic reactions). Comprehensive "multi-omics"   
   studies are massive undertakings that require a variety of different   
   techniques. Aristilde leads one of few labs that carries out such   
   comprehensive studies.   
      
   By examining the relationship among transcriptomics, proteomics,   
   metabolomics and fluxomics, Aristilde and her team mapped the metabolic   
   pathways that bacteria use to degrade plastic and lignin compounds into   
   carbons for food.   
      
   Ultimately, the team discovered that the bacteria first break down the   
   ring of carbons in each compound. After breaking open the ring into   
   a linear structure, the bacteria continue to degrade it into shorter   
   fragments.   
      
   "We started with a plastic or lignin compound that has seven or eight   
   carbons linked together through a core six-carbon circular shape forming   
   the so-called benzene ring," Aristilde explained. "Then, they break   
   that apart into shorter chains that have three or four carbons. In the   
   process, the bacteria feed those broken-down products into their natural   
   metabolism, so they can make amino acids or DNA to help them grow."   
   Upcycling plastic waste Aristilde also discovered that C. testosteroni   
   can direct carbon through different metabolic routes. These routes can   
   lead to useful by-products that can be used for industrially relevant   
   polymers such as plastics. Aristilde and her team are currently working   
   on a project investigating the metabolism that triggers this polymer   
   biosynthesis.   
      
   "These Comamonas species have the potential to make several polymers   
   relevant to biotechnology," Aristilde said. "This could lead to new   
   platforms that generate plastic, decreasing our dependence on petroleum   
   chemicals. One of my lab's major goals is to use renewable resources,   
   such as converting waste into plastic and recycling nutrients from   
   wastes. Then, we won't have to keep extracting petroleum chemicals to   
   make plastics, for instance."  Aristilde is a member of the Institute   
   for Sustainability and Energy at Northwestern's Program on Plastics,   
   Ecosystems and Public Health.   
      
       * RELATED_TOPICS   
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   ==========================================================================   
   Story Source: Materials provided by Northwestern_University. Original   
   written by Amanda Morris. Note: Content may be edited for style and   
   length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Rebecca A. Wilkes, Jacob Waldbauer, Austin Caroll, Manuel Nieto-   
         Domi'nguez, Darren J. Parker, Lichun Zhang, Adam M. Guss, Ludmilla   
         Aristilde. Complex regulation in a Comamonas platform for diverse   
         aromatic carbon metabolism. Nature Chemical Biology, 2023; DOI:   
         10.1038/ s41589-022-01237-7   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/02/230206130644.htm   
      
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