The use of biocatalysis for industrial synthetic chemistry is on the verge of significant growth. Biocatalytic processes can now be carried out in organic solvents as well as aqueous environments, so that apolar organic compounds as well as water-soluble compounds can be modified selectively and efficiently with enzymes and biocatalytically active cells. As the use of biocatalysis for industrial chemical synthesis becomes easier, several chemical companies have begun to increase significantly the number and sophistication of the biocatalytic processes used in their synthesis operations.

Industrial biocatalysis today and tomorrow

Occurrence, synthesis and medical application of bacterial polyhydroxyalkanoate.

Polyhydroxyalkanoates, biopolyesters from renewable resources: Physiological and engineering aspects

https://www.cell.com/trends/biotechnology/pdf/0167-7799(96)10061-5.pdf

Plastic bacteria? Progress and prospects for polyhydroxyalkanoate production in bacteria

Metabolic engineering and pathway construction for biotechnological production of relevant polyhydroxyalkanoates in microorganisms

Pseudomonas oleovorans is able to accumulate poly(3-hydroxyalkanoates) (PHAs) under conditions of excess n-alkanes, which serve as sole energy and carbon source, and limitation of an essential nutrient such as ammonium. In this study we aimed at an efficient production of these PHAs by growing P. oleovorans to high cell densities in fed-batch cultures.To examine the efficiency of our reactor system, P. oleovorans was first grown in batch cultures using n-octane as growth substrate and ammonia water for pH regulation to prevent ammonium limiting conditions. When cell growth ceased due to oxygen limiting conditions, a maximum cell density of 27 g .L(-1) dry weight was obtained. When the growth temperature was decreased from the optimal temperature of 30 degrees -18 degrees C, cell growth continued to a final cell density of 35 g . L(-1) due to a lower oxygen demand of the cells at this lower incubation temperature.To quantify mass transfer rates in our reactor system, the volumetric oxygen transfer coefficient (k(L)a) was determined during growth of P. oleovorans on n-octane. Since the stirrer speed and airflow were increased during growth of the organism, the k(L)a also increased, reaching a constant value of 0.49 s(-1) at maximum airflow and stirrer speed of 2 L . min(-1) and 2500 rpm, respectively. This k(L)a value suggests that oxygen transfer is very efficient in our stirred tank reactor.Using these conditions of high oxygen transfer rates, PHA production by P. oleovorans in fed-batch cultures was studied. The cells were first grown batchwise to a density of 6 g . L(-1), after which a nutrient feed, consisting of (NH(4))(2)SO(4) and MgSO(4), was started. The limiting nutrient ammonium was added at a constant rate of 0.23 g NH(4) (+) per hour, and when after 38 h the feed was stopped, a biomass concentration of 37.1 g . L(-1) was obtained. The Cellular PHA content was 33% (w/w), which is equal to a final PHA yield of 12.1 g . L(-1) and an overall PHA productivity of 0.25 g PHA produced per liter medium per hour.

High cell density cultivation of Pseudomonas oleovorans: Growth and production of poly (3‐hydroxyalkanoates) in two‐liquid phase batch and fed‐batch systems

The alk genes from the catabolic OCT plasmid of Pseudomonas oleovorans, which encode the enzymes involved in the oxidation of n-alkanes to carboxylic acids, were introduced into E. coli W3110. The resulting recombinant converts n-octane in a two-liquid phase medium into the corresponding alkanoate and excretes this compound into the aqueous phase. The rate of octanoic acid production by the recombinant E. coli is equal to or better than the alkane oxidation rate of P. oleovorans, suggesting that two-liquid phase fermentations with E. coli might have future industrial applications.

Bioconversion of N-Octane to Octanoic Acid by a Recombinant Escherichia Coli Cultured in a Two-Liquid Phase Bioreactor

Biooxidation of n-octane by a recombinant Escherichia coli in a two liquid-phase system: effect of medium components on cell growth and alkane oxidation activity.

Olivier Favre-Bulle

Papers

High cell density cultivation of Pseudomonas oleovorans: Growth and production of poly (3‐hydroxyalkanoates) in two‐liquid phase batch and fed‐batch systems

Bioconversion of N-Octane to Octanoic Acid by a Recombinant Escherichia Coli Cultured in a Two-Liquid Phase Bioreactor

Biooxidation of n-octane by a recombinant Escherichia coli in a two liquid-phase system: effect of medium components on cell growth and alkane oxidation activity.