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Microbial isobutyronitrile utilization under haloalkaline conditions
Dimitry Y Sorokin1, Sander van Pelt, Tatjana P Tourova
1Winogradsky Institute of Microbiology, Russian Academy of Sciences, Prospect 60-let Octyabrya 7/2, 117811 Moscow, Russia. soroc@inmi.host.ru
Applied and Environmental Microbiology
|July 24, 2007
Summary
Microbial communities from soda lakes and soils can degrade isobutyronitrile (iBN) at high pH. These consortia, composed of specialized bacteria, demonstrate the potential for whole-cell biocatalysis of nitriles in extreme environments.
Area of Science:
- Microbiology
- Environmental Science
- Biotechnology
Background:
- Haloalkaline environments, such as soda lakes, harbor unique microbial communities adapted to extreme conditions.
- Isobutyronitrile (iBN) is a compound that can serve as a source of carbon and nitrogen.
- Understanding microbial degradation pathways in these environments is crucial for bioremediation and biocatalysis.
Purpose of the Study:
- To investigate the microbial degradation and utilization of isobutyronitrile (iBN) by communities from soda lake sediments and soda soils under haloalkaline conditions (pH 10).
- To identify and characterize the bacterial species involved in these consortia.
- To assess the potential for whole-cell biocatalytic hydrolysis of nitriles in extreme environments.
Main Methods:
- Enrichment and isolation of microbial consortia from soda lake sediments and soda soils capable of degrading iBN at pH 10.
- Bacterial identification using 16S rRNA gene sequencing (implied by "new actinobacterium" and "Bacillus species (RNA group 1)").
- Enzymatic activity assays (nitrile hydratase and amidase) and growth studies under varying pH and substrate conditions.
Main Results:
- Two distinct bacterial consortia capable of complete iBN degradation at pH 10 were identified: one from soda lake sediments (actinobacterium and Marinospirillum) and one from soda soils (two Bacillus species).
- The soda lake consortium showed a division of labor: actinobacterium hydrolyzed nitriles to amides, while Marinospirillum scavenged amides and acids. The soil consortium involved one Bacillus initiating hydrolysis and another utilizing products.
- Isolated strains were moderately salt-tolerant alkaliphiles (growth pH 7.0-10.5), with intracellular nitrile hydratase and amidase activities optimal at near-neutral pH.
Conclusions:
- Microbial consortia can effectively degrade isobutyronitrile at highly alkaline pH (10).
- Specialized bacterial partnerships facilitate the complete breakdown of nitriles in soda environments.
- Whole-cell biocatalysis of various nitriles is feasible under haloalkaline conditions, despite intracellular enzyme optima.
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