Study on the Production and Re-use of Poly(3-hydroxybutyrate-co-3- hydroxyvalerate) and Extracellular Polysaccharide by the Archaeon Haloferax mediterranei Strain DSM 1411

Abstract

The halobacterium Haloferax mediterranei was used to study the production of two types of biopolymers: The biopolyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was accumulated as intracellular granules, whereas an extracelluar polysaccharide was excreted in parallel to biopolyester synthesis.After production, microbial re-use and degradation of these polymers under different conditions were investigated to assess the requirements for handling the product-rich fermentation broth prior to the downstream processing for product recovery. Degradation kinetics of the polymers and the impact of different storage conditions on molar mass of PHBV were studied.It turned out that the biotechnological fermentation process can be run without any sterility precautions. No major product losses were observed without pasteurization of fermentation broth after the stop of fermentation. In addition, neither PHBV nor EPS are re-utilized by the cells for biomass formation even if the culture is maintained under conditions of carbon starvation for an extended time.

A strategy for dual biopolymer production of P(3HB) and γ-PGA

“…Simultaneous or sequential production of two biopolymers with another bio‐product has been reported previously. However, in many cases this has been based on unplanned, ad hoc observation rather than prior deliberate design . So, there is great opportunity for structured investigation, leading to potential economic advantages for bio‐industries.…”

“…However, in many cases this has been based on unplanned, ad hoc observation rather than prior deliberate design. [15][16][17][18] there is great opportunity for structured investigation, leading to potential economic advantages for bio-industries. Simultaneous production of industrially important biopolymers is an attractive approach for a high-profit bio-refinery.…”

Production of Polyhydroxyalkanoate (PHA) Biopolyesters by Extremophiles?

“…Whereas some of these groups focused on the application of inexpensive carbon feedstocks to safe substrate costs, such as whey permeate from dairy industry [12,13,48], rice-based ethanol stillage [49], extruded rice bran [50], enzymatically extruded starch [51], crude glycerol phase [28], olive mill waste water [52], vinasse [53], etc., others clarified the enzymatic and genetic background of PHA-synthesis [54][55][56][57] and in vitro degradation [58] by this organisms. Mathematic models of PHA-production [59], and kinetic studies of PHA and by-product synthesis and degradation [60] were reported for Hfx. mediterannei.…”

Poly[(R)-3-hydroxybutyrate] production under different salinity conditions by a novel Bacillus megaterium strain

“…Representatives of the latter group of microorganisms have shown a great potential for biotechnological production of, inter alia, polyhydroxyalkanoates (PHAs). For example, PHA biosynthesis by the halophilic strain Halomonas boliviensis [6] and the extremely halophilic archaeon Haloferax mediterranei [7][8][9] are described in the literature. In addition, many Bacillus species have been classified as halotolerant [10] and constitute potential candidates for PHA production.…”