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Screening for MCL-PHA-producing fluorescent pseudomonads and comparison of MCL-PHA production under iso-osmotic
Ekta Khare1, Jyotsana Chopra, Naveen Kumar Arora
1Department of Microbiology, Institute of Biosciences and Biotechnology, Chhatrapati Shahu Ji Maharaj University, Kanpur, India, ekhare@rediffmail.com.
Abstract:
The medium chain length polyhydroxyalkanoates (MCL-PHA) have attracted much attention from academic and industrial communities for their interesting applications in medical field. The aim of this study was to screen high MCL-PHA-producing fluorescent pseudomonads, and to compare the effect of osmotic stress generated by NaCl (ionic) and polyethylene glycol (PEG, non-ionic inert polymer) on PHA production. A total of 50 fluorescent pseudomonads isolated from rhizospheric soil were screened for PHA production by Sudan Black staining. Out of all the PHA-producing isolates only five were MCL-PHA producers as detected by MCL-PCR. Isolate Bar1 identified as Pseudomonas fluorescens by 16S rRNA gene sequencing was selected for further analysis due to its high MCL-PHA production ability. The iso-osmotic stress generated by NaCl and PEG-6000 showed 5.75- and 3.19-fold enhanced production of PHA at -2 bar osmotic potential, over control (0 bar), respectively. There was 1.8-fold enhanced production of PHA at -2 bar osmotic stress induced by NaCl over PEG. PEG reduces availability of water to microorganisms without reducing exogenously provided nutrients which appear to be responsible for its down performance over NaCl. The FTIR analysis of PHA sample purified from cells showed strong marker bands near 1742, 2870, 1170, 1099, and 2926 cm(-1), corresponding to MCL-PHA. The study reported that supplementation of NaCl (electrolyte) in growth media enhances the production of MCL-PHA which can be very useful for its industrial production.
Insights
High production of medium chain length polyhydroxyalkanoates (MCL-PHA) was achieved using Pseudomonas fluorescens under NaCl-induced osmotic stress. This method significantly enhances MCL-PHA yield for industrial applications.
Area of Science:
- Microbiology and Biotechnology
- Polymer Science
Background:
- Medium chain length polyhydroxyalkanoates (MCL-PHA) are biopolymers with significant potential in the medical field.
- Optimizing MCL-PHA production is crucial for industrial viability and application development.
Purpose of the Study:
- To screen fluorescent pseudomonads for high MCL-PHA production.
- To investigate the impact of ionic (NaCl) versus non-ionic (PEG) osmotic stress on MCL-PHA yield.
- To identify optimal conditions for enhanced industrial production of MCL-PHA.
Main Methods:
- Screening of 50 rhizospheric fluorescent pseudomonads for PHA production using Sudan Black staining.
- Identification of MCL-PHA producers via MCL-PCR and 16S rRNA gene sequencing (Pseudomonas fluorescens Bar1).
- Application of iso-osmotic stress (-2 bar) using NaCl and PEG-6000 to evaluate PHA production enhancement.
- Fourier-transform infrared (FTIR) spectroscopy for PHA structural confirmation.
Main Results:
- Five isolates confirmed as MCL-PHA producers; Pseudomonas fluorescens Bar1 identified as a high producer.
- NaCl-induced osmotic stress resulted in a 5.75-fold increase in PHA production compared to control.
- PEG-6000 stress led to a 3.19-fold increase, with NaCl showing 1.8-fold higher enhancement than PEG.
- FTIR analysis confirmed the presence of characteristic MCL-PHA functional groups.
Conclusions:
- Supplementation of NaCl in growth media significantly enhances MCL-PHA production in Pseudomonas fluorescens.
- Ionic osmotic stress is more effective than non-ionic stress for boosting MCL-PHA yield.
- The findings support the industrial production of MCL-PHA using electrolyte-enhanced fermentation.
