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Identifying Amino Acid Overproducers Using Rare-Codon-Rich Markers
Published on: June 24, 2019
Identification and methionine analog tolerance of environmental bacterial isolates selected on methionine analog
Suwat Saengkerdsub1, Arunachalam Muthaiyan, Jody M Lingbeck
1a Center for Food Safety, and Department of Food Science , University of Arkansas , Fayetteville , Arkansas , USA.
Abstract:
Methionine is the first limiting amino acid in poultry feed. Currently, methionine supplement is synthesized from an expensive chemical process requiring hazardous chemicals. Therefore, the objectives of this study were isolation of methionine producing bacteria from environmental samples and quantification of methionine production in these isolated bacteria. MCGC medium was selected as the isolation medium for methionine-producing bacteria by using Corynebacterium glutamicum ATCC13032 and Escherichia coli ATCC23798 as the positive and negative controls, respectively. Thirty-nine bacterial strains were obtained from environmental samples. Only strains A121, A122, A151 and A181 were able to tolerate up to 0.1% (w/v) of ethionine or norleucine. These isolated strains were identified by sequencing small subunit rRNA genes. The results revealed that bacterial strains A121, A122, A151and A181 were Klebsiella species, Acinetobacter baumannii, A. baumannii and Pseudomonas aeruginosa, respectively. When methionine production in strains A121 and A181 was quantitated, strains A121 and A181 generated methionine up to 31.1 and 124.6 μg/ml, respectively.
Insights
Researchers isolated methionine-producing bacteria from environmental samples to find a sustainable alternative to chemical synthesis. Pseudomonas aeruginosa strain A181 showed the highest methionine yield, offering potential for improved poultry feed additives.
Area of Science:
- Microbiology
- Biotechnology
- Animal Nutrition
Background:
- Methionine is an essential amino acid for poultry, often limiting in feed.
- Current synthetic methionine production is costly and relies on hazardous chemicals.
- There is a need for sustainable and cost-effective methionine sources.
Purpose of the Study:
- To isolate and identify environmental bacteria capable of producing methionine.
- To quantify methionine production in selected bacterial isolates.
- To explore microbial alternatives for methionine supplementation in animal feed.
Main Methods:
- Isolation of methionine-producing bacteria using MCGC medium with ethionine and norleucine as selective agents.
- Identification of promising bacterial strains via small subunit rRNA gene sequencing.
- Quantification of methionine production using established analytical methods.
Main Results:
- Thirty-nine bacterial strains were isolated; four (A121, A122, A151, A181) showed tolerance to selective agents.
- Identified strains included Klebsiella spp., Acinetobacter baumannii, and Pseudomonas aeruginosa.
- Pseudomonas aeruginosa A181 produced the highest amount of methionine (124.6 μg/ml), followed by Klebsiella spp. A121 (31.1 μg/ml).
Conclusions:
- Environmental bacteria, particularly Pseudomonas aeruginosa, can be a viable source of methionine.
- Microbial methionine production offers a potential sustainable alternative to chemical synthesis for animal feed.
- Further research can optimize conditions for enhanced methionine yield from these isolates.
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