Optimization of Methane Feed and N:C Ratio for Biomass and Polyhydroxybutyrate Production by the Alphaproteobacterial Methanotroph <i>Methylocystis</i> sp. Rockwell
The consumption of methane and the production of biodegradable polymers using alphaproteobacterial methanotrophs offers a promising strategy to mitigate greenhouse gas emissions and reduce non-biodegradable plastic pollution. This study identified an ideal amount of added methane and N:C ratio in 10...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-12-01
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| Series: | Methane |
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| Online Access: | https://www.mdpi.com/2674-0389/1/4/26 |
| _version_ | 1797623850862641152 |
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| author | Hem K. Sharma Dominic Sauvageau Lisa Y. Stein |
| author_facet | Hem K. Sharma Dominic Sauvageau Lisa Y. Stein |
| author_sort | Hem K. Sharma |
| collection | DOAJ |
| description | The consumption of methane and the production of biodegradable polymers using alphaproteobacterial methanotrophs offers a promising strategy to mitigate greenhouse gas emissions and reduce non-biodegradable plastic pollution. This study identified an ideal amount of added methane and N:C ratio in 100 mL batch cultures of the alphaproteobacterial methanotroph <i>Methylocystis</i> sp. Rockwell growing in 1-L sealed bottles using Response Surface Methodology (RSM) to achieve both high biomass and high polyhydroxybutyrate (PHB) production. RSM analysis showed achievement of optimal biomass at 474.7 ± 10.1 mg/L in nitrate mineral salts (NMS) medium and 480.0 ± 65.5 mg/L biomass in ammonium mineral salts (AMS) medium with 8 mmol of methane and an N:C ratio of 0.022. However, optimal PHB concentration was achieved with 6 mmol methane at N:C ratios of 0.012 in NMS medium (149.7 ± 16.1 mg/L) and 0.022 in AMS medium (200.3 ± 5.1 mg/L). A multi-objective RSM analysis projected maxima in PHB production and %PHB cell content (based on dry weight) when using 4.88 mmol methane and N:C ratio of 0.016 in NMS cultures, and 6.28 mmol methane and the 0.016 N:C ratio in AMS cultures. Cultures grown under these projected conditions produced 173.7 mg PHB/L with 46.8% PHB cell content in NMS and 196.9 mg/L with 53.1% PHB cell content in AMS. Taken together, these analyses predicted the optimal conditions for growth and PHB production in batch cultures of <i>Methylocystis</i> sp. Rockwell and confirmed a preference for ammonium as the N-source for PHB production. This information is valuable for media formulation in industrial scale-up of <i>Methylocystis</i> sp. Rockwell in PHB production. |
| first_indexed | 2024-03-11T09:34:40Z |
| format | Article |
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| institution | Directory Open Access Journal |
| issn | 2674-0389 |
| language | English |
| last_indexed | 2024-03-11T09:34:40Z |
| publishDate | 2022-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Methane |
| spelling | doaj.art-b92efcce9fa746c582e2c0c6fa8cb63b2023-11-16T17:24:57ZengMDPI AGMethane2674-03892022-12-011435536410.3390/methane1040026Optimization of Methane Feed and N:C Ratio for Biomass and Polyhydroxybutyrate Production by the Alphaproteobacterial Methanotroph <i>Methylocystis</i> sp. RockwellHem K. Sharma0Dominic Sauvageau1Lisa Y. Stein2Department of Biological Sciences, CW 405 Biological Sciences Building, University of Alberta, Edmonton, AB T6G 2E9, CanadaDepartment of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, CanadaDepartment of Biological Sciences, CW 405 Biological Sciences Building, University of Alberta, Edmonton, AB T6G 2E9, CanadaThe consumption of methane and the production of biodegradable polymers using alphaproteobacterial methanotrophs offers a promising strategy to mitigate greenhouse gas emissions and reduce non-biodegradable plastic pollution. This study identified an ideal amount of added methane and N:C ratio in 100 mL batch cultures of the alphaproteobacterial methanotroph <i>Methylocystis</i> sp. Rockwell growing in 1-L sealed bottles using Response Surface Methodology (RSM) to achieve both high biomass and high polyhydroxybutyrate (PHB) production. RSM analysis showed achievement of optimal biomass at 474.7 ± 10.1 mg/L in nitrate mineral salts (NMS) medium and 480.0 ± 65.5 mg/L biomass in ammonium mineral salts (AMS) medium with 8 mmol of methane and an N:C ratio of 0.022. However, optimal PHB concentration was achieved with 6 mmol methane at N:C ratios of 0.012 in NMS medium (149.7 ± 16.1 mg/L) and 0.022 in AMS medium (200.3 ± 5.1 mg/L). A multi-objective RSM analysis projected maxima in PHB production and %PHB cell content (based on dry weight) when using 4.88 mmol methane and N:C ratio of 0.016 in NMS cultures, and 6.28 mmol methane and the 0.016 N:C ratio in AMS cultures. Cultures grown under these projected conditions produced 173.7 mg PHB/L with 46.8% PHB cell content in NMS and 196.9 mg/L with 53.1% PHB cell content in AMS. Taken together, these analyses predicted the optimal conditions for growth and PHB production in batch cultures of <i>Methylocystis</i> sp. Rockwell and confirmed a preference for ammonium as the N-source for PHB production. This information is valuable for media formulation in industrial scale-up of <i>Methylocystis</i> sp. Rockwell in PHB production.https://www.mdpi.com/2674-0389/1/4/26methanotrophic bacteria<i>Methylocystis</i> sp. RockwellN:C ratiopolyhydroxybutyrateresponse surface methodologysingle carbon bioconversion |
| spellingShingle | Hem K. Sharma Dominic Sauvageau Lisa Y. Stein Optimization of Methane Feed and N:C Ratio for Biomass and Polyhydroxybutyrate Production by the Alphaproteobacterial Methanotroph <i>Methylocystis</i> sp. Rockwell Methane methanotrophic bacteria <i>Methylocystis</i> sp. Rockwell N:C ratio polyhydroxybutyrate response surface methodology single carbon bioconversion |
| title | Optimization of Methane Feed and N:C Ratio for Biomass and Polyhydroxybutyrate Production by the Alphaproteobacterial Methanotroph <i>Methylocystis</i> sp. Rockwell |
| title_full | Optimization of Methane Feed and N:C Ratio for Biomass and Polyhydroxybutyrate Production by the Alphaproteobacterial Methanotroph <i>Methylocystis</i> sp. Rockwell |
| title_fullStr | Optimization of Methane Feed and N:C Ratio for Biomass and Polyhydroxybutyrate Production by the Alphaproteobacterial Methanotroph <i>Methylocystis</i> sp. Rockwell |
| title_full_unstemmed | Optimization of Methane Feed and N:C Ratio for Biomass and Polyhydroxybutyrate Production by the Alphaproteobacterial Methanotroph <i>Methylocystis</i> sp. Rockwell |
| title_short | Optimization of Methane Feed and N:C Ratio for Biomass and Polyhydroxybutyrate Production by the Alphaproteobacterial Methanotroph <i>Methylocystis</i> sp. Rockwell |
| title_sort | optimization of methane feed and n c ratio for biomass and polyhydroxybutyrate production by the alphaproteobacterial methanotroph i methylocystis i sp rockwell |
| topic | methanotrophic bacteria <i>Methylocystis</i> sp. Rockwell N:C ratio polyhydroxybutyrate response surface methodology single carbon bioconversion |
| url | https://www.mdpi.com/2674-0389/1/4/26 |
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