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.