Abstract
•First report on sugars derived from grass biomass as substrate for mcl-PHA production.•Pseudomonas strains utilized grass hydrolysates as a sole carbon and energy source.•Bacterial strains converted both hexose and pentose sugars to mcl-PHA.•Growth and PHA yields on hydrolysates were comparable to commercial sugars.
This study investigated the potential of grass biomass as a feedstock for mcl-PHA production. Pretreatments (2% NaOH at 120°C or hot water at 120°C) of perennial ryegrass were employed alone or in combination with sodium chlorite/acetic acid (SC/AA) delignification to evaluate the enzymatic digestibility and subsequent utilization of resultant sugars by Pseudomonas strains. NaOH pretreated sample had better digestibility than raw and hot water treated samples and this hydrolysate supported good growth of all tested strains with limited mcl-PHA (6–17% of cell dry mass (CDM)) accumulation. Digestibility of both untreated and pretreated samples was improved after SC/AA delignification and produced glucose (74–77%) rich hydrolysates. Tested strains accumulated 20–34% of CDM as PHA when these hydrolysates were used as sole carbon and energy source. CDM and PHA yields obtained for these strains when tested with laboratory grade sugars was similar to that achieved with grass derived sugars.