Sucrose supplementation suppressed the growth inhibition in polyhydroxyalkanoate-producing plants

Abstract

Polyhydroxyalkanoate (PHA) is a thermoplastic polymer with several advantageous properties, including biomass origin, biocompatibility, and biodegradability. PHA is synthesized in transgenic plants harboring 3 enzymatic genes: phaA, phaB, and phaC (collectively referred to as phaABC). PHA-producing plants exhibit severe growth inhibition that leads to extremely low PHA accumulation when these enzymes are localized in the cytosol. This growth inhibition could be attributed to the deleterious effects of the PHA biosynthetic pathway on endogenous essential metabolites or to PHA cytotoxicity itself. We performed precise morphological observations of phaABC-overexpressing Arabidopsis (ABC-ox), which displayed typical growth inhibition. On growth medium without sucrose, ABC-ox exhibited a pale green phenotype, dwarfism, including small cotyledons and true leaves, and short roots. ABC-ox partially recovered from this growth inhibition when the growth medium was supplemented with 1% sucrose. This recovery was reversed after ABC-ox grown on 1% sucrose medium was transferred to soil. ABC-ox grown on 1% sucrose medium not only demonstrated recovery from growth inhibition but were also the only examined plants with PHA accumulation, suggesting that growth inhibition was not caused by PHA cytotoxicity but rather by a lack of essential metabolites.

Marine Purple Photosynthetic Bacteria as Sustainable Microbial Production Hosts

“…In addition, the supply of those carbon sources is not stable because of natural environmental factors such unexpected weather and natural disasters. To solve the problems, direct production of PHA from CO 2 via photosynthesis has been investigated using cyanobacteria and plants (Osanai et al, 2013; Yoshizumi et al, 2017). Among photosynthetic organisms, purple photosynthetic bacteria are known to have better ability to produce PHA (Liebergesell et al, 1991).…”