1
|
Schmid M, Raschbauer M, Song H, Bauer C, Neureiter M. Effects of nutrient and oxygen limitation, salinity and type of salt on the accumulation of poly(3-hydroxybutyrate) in Bacillus megaterium uyuni S29 with sucrose as a carbon source. N Biotechnol 2020; 61:137-144. [PMID: 33278638 DOI: 10.1016/j.nbt.2020.11.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 11/25/2020] [Accepted: 11/28/2020] [Indexed: 12/12/2022]
Abstract
Due to high manufacturing costs, industrial production and application of bio-based polyhydroxyalkanoates (PHA) as bioplastics remain below the expected potential. Improving yields and productivities during biotechnological production will contribute to eliminating existing shortcomings and should therefore be a priority in process development with new strains and substrates. The present study investigates key parameters such as different nutrient and oxygen limitation strategies and the salinity and type of salt to determine their impact on growth and poly(3-hydroxybutyrate) (P(3HB)) formation behaviour of Bacillus megaterium. The oxygen-limiting conditions applied resulted in a longer process duration and were found to be least effective with regard to P(3HB) content in the biomass. A higher P(3HB) content of 0.42 g g-1 was achieved when nitrogen was limited compared to 0.34 g g-1 under phosphate-limiting conditions; however, sucrose utilization was better when phosphate was limited. Replacing NaCl by KCl and evaluating different concentrations ranging from 0.08 to 1.7 mol L-1 in the process medium showed that B. megaterium has a higher tolerance to KCl as the biomass and P(3HB) formation was increased to 0.48 g g-1 compared to 0.36 g g-1. The combination of applying KCl instead of NaCl together with phosphorous limitation significantly increased P(3HB) productivity to 0.25 g L-1 h-1 compared to 0.09 g L-1 h-1. It can be concluded that the effective utilization of sucrose as a carbon source requires a combination of high nitrogen and low phosphorous concentration and a salt content of 0.6 g L-1 KCl for P(3HB) production with B. megaterium uyuni S29.
Collapse
Affiliation(s)
- Maximilian Schmid
- University of Natural Resources and Life Sciences, Vienna, Institute of Environmental Biotechnology, Tulln an der Donau, Austria
| | - Michaela Raschbauer
- University of Natural Resources and Life Sciences, Vienna, Institute of Environmental Biotechnology, Tulln an der Donau, Austria
| | - Hyunjeong Song
- University of Natural Resources and Life Sciences, Vienna, Institute of Environmental Biotechnology, Tulln an der Donau, Austria
| | - Cornelia Bauer
- University of Natural Resources and Life Sciences, Vienna, Institute of Environmental Biotechnology, Tulln an der Donau, Austria
| | - Markus Neureiter
- University of Natural Resources and Life Sciences, Vienna, Institute of Environmental Biotechnology, Tulln an der Donau, Austria.
| |
Collapse
|
2
|
Cubillos CF, Paredes A, Yáñez C, Palma J, Severino E, Vejar D, Grágeda M, Dorador C. Insights Into the Microbiology of the Chaotropic Brines of Salar de Atacama, Chile. Front Microbiol 2019; 10:1611. [PMID: 31354691 PMCID: PMC6637823 DOI: 10.3389/fmicb.2019.01611] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 06/27/2019] [Indexed: 02/02/2023] Open
Abstract
Microbial life inhabiting hypersaline environments belong to a limited group of extremophile or extremotolerant taxa. Natural or artificial hypersaline environments are not limited to high concentrations of NaCl, and under such conditions, specific adaptation mechanisms are necessary to permit microbial survival and growth. Argentina, Bolivia, and Chile include three large salars (salt flats) which globally, represent the largest lithium reserves, and are commonly referred to as the Lithium Triangle Zone. To date, a large amount of information has been generated regarding chemical, geological, meteorological and economical perspectives of these salars. However, there is a remarkable lack of information regarding the biology of these unique environments. Here, we report the presence of two bacterial strains (isolates LIBR002 and LIBR003) from one of the most hypersaline lithium-dominated man-made environments (total salinity 556 g/L; 11.7 M LiCl) reported to date. Both isolates were classified to the Bacillus genera, but displayed differences in 16S rRNA gene and fatty acid profiles. Our results also revealed that the isolates are lithium-tolerant and that they are phylogenetically differentiated from those Bacillus associated with high NaCl concentration environments, and form a new clade from the Lithium Triangle Zone. To determine osmoadaptation strategies in these microorganisms, both isolates were characterized using morphological, metabolic and physiological attributes. We suggest that our characterization of bacterial isolates from a highly lithium-enriched environment has revealed that even at such extreme salinities with high concentrations of chaotropic solutes, scope for microbial life exists. These conditions have previously been considered to limit the development of life, and our work extends the window of life beyond high concentrations of MgCl2, as previously reported, to LiCl. Our results can be used to further the understanding of salt tolerance, most especially for LiCl-dominated brines, and likely have value as models for the understanding of putative extra-terrestrial (e.g., Martian) life.
Collapse
Affiliation(s)
- Carolina F. Cubillos
- Laboratorio de Complejidad Microbiana y Ecología Funcional, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
- Department of Chemical Engineering and Mineral Process, Center for Advanced Study of Lithium and Industrial Minerals, Universidad de Antofagasta, Antofagasta, Chile
- Centre for Biotechnology and Bioengineering, Universidad de Chile, Santiago, Chile
| | - Adrián Paredes
- Laboratorio Química Biológica, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
- Departamento de Química, Facultad de Ciencias Básicas, Universidad de Antofagasta, Antofagasta, Chile
| | - Carolina Yáñez
- Laboratorio Microbiología, Instituto de Biología, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Jenifer Palma
- Departamento de Ciencias de los Alimentos, Facultad de Ciencias de la Salud, Universidad de Antofagasta, Antofagasta, Chile
| | - Esteban Severino
- Laboratorio de Complejidad Microbiana y Ecología Funcional, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| | - Drina Vejar
- Laboratorio de Complejidad Microbiana y Ecología Funcional, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
- Centre for Biotechnology and Bioengineering, Universidad de Chile, Santiago, Chile
| | - Mario Grágeda
- Department of Chemical Engineering and Mineral Process, Center for Advanced Study of Lithium and Industrial Minerals, Universidad de Antofagasta, Antofagasta, Chile
| | - Cristina Dorador
- Laboratorio de Complejidad Microbiana y Ecología Funcional, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
- Centre for Biotechnology and Bioengineering, Universidad de Chile, Santiago, Chile
- Departamento de Biotecnología, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Antofagasta, Chile
| |
Collapse
|