From Waste to Plastic: Synthesis of Poly(3-Hydroxypropionate) in Shimwellia blattae

Abstract

bIn recent years, glycerol has become an attractive carbon source for microbial processes, as it accumulates massively as a byproduct of biodiesel production, also resulting in a decline of its price. A potential use of glycerol in biotechnology is the synthesis of poly(3-hydroxypropionate) [poly(3HP)], a biopolymer with promising properties which is not synthesized by any known wild-type organism. In this study, the genes for 1,3-propanediol dehydrogenase (dhaT) and aldehyde dehydrogenase (aldD) of Pseudomonas putida KT2442, propionate-coenzyme A (propionate-CoA) transferase (pct) of Clostridium propionicum X2, and polyhydroxyalkanoate (PHA) synthase (phaC1) of Ralstonia eutropha H16 were cloned and expressed in the 1,3-propanediol producer Shimwellia blattae. In a two-step cultivation process, recombinant S. blattae cells accumulated up to 9.8% ؎ 0.4% (wt/wt [cell dry weight]) poly(3HP) with glycerol as the sole carbon source. Furthermore, the engineered strain tolerated the application of crude glycerol derived from biodiesel production, yielding a cell density of 4.05 g cell dry weight/liter in a 2-liter fedbatch fermentation process.

1,3-Propanediol production from glycerol with a novel biocatalyst Shimwellia blattae ATCC 33430: Operational conditions and kinetics in batch cultivations

“…S. blattae ATCC 33430 is capable of producing PDO from glycerol by the enzymatic system described below (Andres et al, 2004) and it's also employed to synthesize poly(3-hydroxypropionate), a biopolymer derived from 3-HPA, by engineered strains that may accumulate almost 10% w/w [CDW] of this product inside the cells (Heinrich et al, 2013).…”

Poly(3-Hydroxypropionate): a Promising Alternative to Fossil Fuel-Based Materials

“…Hitherto, the highest productivities for poly(3HP) synthesis were achieved from substrates such as 3HP and 1,3PD (28) and from addition of cofactors such as vitamin B 12 and inducers (22,27), respectively. Until now, productivities of processes avoiding the addition of vitamin B 12 were about 5-to 10-fold lower (29,33). For low-cost production, those processes are more promising and should be further optimized.…”

“…Since chromosomal integrations or plasmid addiction systems stabilize the poly(3HP) pathways, addition of antibiotics is no longer needed (27,33). Furthermore, employing natural vitamin B 12 producers as hosts can overcome the need for cost-intensive cofactors (29,33). Hence, most processes use pure glycerol.…”

“…To use a cheaper substrate and to avoid the addition of vitamin B 12 , Heinrich et al modified this pathway for poly(3HP) synthesis and introduced a new expression host, Shimwellia blattae (29). S. blattae, formerly known as Escherichia blattae, is a natural 1,3PD and vitamin B 12 producer and was isolated from the hindgut of the cockroach Blatta orientalis (30)(31)(32).…”

“…Under anaerobic conditions, however, cell growth of most expression hosts is diminished. Therefore, and as aerobic processes give higher cell densities, vitamin B 12 -dependent glycerol dehydrates should be employed and expressed in natural vitamin B 12 -producing hosts to overcome the need for addition of expensive cofactors (29,33).…”