Introducing the Newly Isolated Bacterium Aneurinibacillus sp. H1 as an Auspicious Thermophilic Producer of Various Polyhydroxyalkanoates (PHA) Copolymers–2. Material Study on the Produced Copolymers

Abstract

Aneurinibacillus sp. H1 is a promising, moderately thermophilic, novel Gram-positive bacterium capable of the biosynthesis of polyhydroxyalkanoates (PHA) with tunable monomer composition. In particular, the strain is able to synthesize copolymers of 3-hydroxybutyrate (3HB), 4-hydroxybutyrate (4HB) and 3-hydroxyvalerate (3HV) with remarkably high 4HB and 3HV fractions. In this study we performed an in-depth material analysis of PHA polymers produced by Aneurinibacillus sp. H1 in order to describe how the monomer composition affects fundamental structural and physicochemical parameters of the materials in the form of solvent-casted films. Results of infrared spectroscopy, X-ray diffractometry and thermal analysis clearly show that controlling the monomer composition enables optimization of PHA crystallinity both qualitatively (the type of the crystalline lattice) and quantitatively (the overall degree of crystallinity). Furthermore, resistance of the films against thermal and/or enzymatic degradation can also be manipulated by the monomer composition. Results of this study hence confirm Aneurinibacillus sp. H1 as an auspicious candidate for thermophilic production of PHA polymers with material properties that can be tuned together with their chemical composition by the corresponding adjustment of the cultivation process.

Effects of Differing Monomer Compositions on Properties of P(3HB-co-4HB) Synthesized by Aneurinibacillus sp. H1 for Various Applications

“…The ratio between P3HB and P4HB crystallites gradually shifted with changing copolymer composition, confirming the copolymer composition found by the GC-FID method. The diffraction patterns correspond well with previously described data [ 12 ] obtained on materials produced by the same microorganism as in this work. Other authors (see Ref.…”

“…H1 reaches lower cell dry mass/biomass yields, and the obtained biomass is quite poor in PHA content as compared to C. necator (see Table 1 ). Furthermore, produced copolymers dispose of a significantly lower average molecular weight than homopolymers, which is given by the difference in PHA synthase types of the respective producents and their general biological dissimilarity (as proposed in [ 12 ]), and possible polymerization termination by glycerol [ 13 , 14 ]. On the other hand, manipulating the monomer composition is expected to broaden the range of accessible physical and material properties (crystallinity, ultimate tensile strength), resulting in higher applicability.…”

Current Advances towards 4-Hydroxybutyrate Containing Polyhydroxyalkanoates Production for Biomedical Applications

“…However, when supplemented with 1,4-butanediol, the strain produced P(3HB- co -4HB) with 4HB molar fraction up to 90 mol%. Moreover, by cofeeding valerate, it was able to synthesize terpolymer P(3HB- co -33 mol% 3HV- co -54 mol% 4HB) [ 25 ].…”

Genome-Driven Discovery of Enzymes with Industrial Implications from the Genus Aneurinibacillus

“…Recently, it was reported that Aneurinibacillus sp. H1 has potential for the biosynthesis of polyhydroxyalkanoates (PHA) on an industrial scale, and its capacity for production of copolymers such as 3-hydroxybutyrate (3HB), 4-hydroxybutyrate (4HB), and 3-hydroxyvalerate (3HV) with exceptionally high 4HB and 3HV fractions [22]. Furthermore, A. aneurinilyticus DBT87 isolated from the swine and goat can produce cellulase and xylanase enzymes, which can degrade lignocellulose biomass [23].…”

“…However, only a limited number of genomes were used in such studies. This limits our understanding of the complete potential of microorganisms, which have shown great capabilities for diverse types of enzyme activities, or the production of bioactive compounds [16,22,[37][38][39][40]. Therefore, in this work we apply genome mining approaches to investigate the biosynthetic potential as well as explore the diverse sets of enzymes for biomass degradation and heavy metal resistance present in Aneurinibacillus genomes.…”