scholarly journals Microbial Polyhydroxyalkanoates Granules: An Approach Targeting Biopolymer for Medical Applications and Developing Bone Scaffolds

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 860
Author(s):  
Moushmi Goswami ◽  
Pavni Rekhi ◽  
Mousumi Debnath ◽  
Seeram Ramakrishna
Keyword(s):  
Chain Length ◽  
Sol Gel ◽  
Barrier Properties ◽  
Drug Carriers ◽  
Mechanical And Thermal Properties ◽  
Bone Scaffold ◽  
Short Chain Length ◽  
Medium Chain Length ◽  
Polyhydroxy Butyrate ◽  
Bacterial Sources

Microbial polyhydroxyalkanoates (PHA) are proteinaceous storage granules ranging from 100 nm to 500 nm. Bacillus sp. serve as unique bioplastic sources of short-chain length and medium-chain length PHA showcasing properties such as biodegradability, thermostability, and appreciable mechanical strength. The PHA can be enhanced by adding functional groups to make it a more industrially useful biomaterial. PHA blends with hydroxyapatite to form nanocomposites with desirable features of compressibility. The reinforced matrices result in nanocomposites that possess significantly improved mechanical and thermal properties both in solid and melt states along with enhanced gas barrier properties compared to conventional filler composites. These superior qualities extend the polymeric composites’ applications to aggressive environments where the neat polymers are likely to fail. This nanocomposite can be used in different industries as nanofillers, drug carriers for packaging essential hormones and microcapsules, etc. For fabricating a bone scaffold, electrospun nanofibrils made from biocomposite of hydroxyapatite and polyhydroxy butyrate, a form of PHA, can be incorporated with the targeted tissue. The other methods for making a polymer scaffold, includes gas foaming, lyophilization, sol–gel, and solvent casting method. In this review, PHA as a sustainable eco-friendly NextGen biomaterial from bacterial sources especially Bacillus cereus, and its application for fabricating bone scaffold using different strategies for bone regeneration have been discussed.

scholarly journals Characterization of Site-Specific Mutations in a Short-Chain-Length/Medium-Chain-Length Polyhydroxyalkanoate Synthase:In VivoandIn VitroStudies of Enzymatic Activity and Substrate Specificity

2013 ◽  
Vol 79 (12) ◽  
pp. 3813-3821 ◽  
Author(s):  
Jo-Ann Chuah ◽  
Satoshi Tomizawa ◽  
Miwa Yamada ◽  
Takeharu Tsuge ◽  
Yoshiharu Doi ◽  
...  
Keyword(s):  
Chain Length ◽  
Fold Increase ◽  
Short Chain ◽  
Pha Synthase ◽  
Wild Type ◽  
Short Chain Length ◽  
Medium Chain ◽  
Medium Chain Length

ABSTRACTSaturation point mutagenesis was carried out at position 479 in the polyhydroxyalkanoate (PHA) synthase fromChromobacteriumsp. strain USM2 (PhaCCs) with specificities for short-chain-length (SCL) [(R)-3-hydroxybutyrate (3HB) and (R)-3-hydroxyvalerate (3HV)] and medium-chain-length (MCL) [(R)-3-hydroxyhexanoate (3HHx)] monomers in an effort to enhance the specificity of the enzyme for 3HHx. A maximum 4-fold increase in 3HHx incorporation and a 1.6-fold increase in PHA biosynthesis, more than the wild-type synthase, was achieved using selected mutant synthases. These increases were subsequently correlated with improved synthase activity and increased preference of PhaCCsfor 3HHx monomers. We found that substitutions with uncharged residues were beneficial, as they resulted in enhanced PHA production and/or 3HHx incorporation. Further analysis led to postulations that the size and geometry of the substrate-binding pocket are determinants of PHA accumulation, 3HHx fraction, and chain length specificity.In vitroactivities for polymerization of 3HV and 3HHx monomers were consistent within vivosubstrate specificities. Ultimately, the preference shown by wild-type and mutant synthases for either SCL (C4and C5) or MCL (C6) substrates substantiates the fundamental classification of PHA synthases.

scholarly journals Characterization of a Novel Subgroup of Extracellular Medium-Chain-Length Polyhydroxyalkanoate Depolymerases from Actinobacteria

2012 ◽  
Vol 78 (20) ◽  
pp. 7229-7237 ◽  
Author(s):  
Joana Gangoiti ◽  
Marta Santos ◽  
María Auxiliadora Prieto ◽  
Isabel de la Mata ◽  
Juan L. Serra ◽  
...  
Keyword(s):  
Chain Length ◽  
De Novo ◽  
Hydrolysis Product ◽  
Maximum Activity ◽  
Short Chain Length ◽  
Great Ability ◽  
Content Type ◽  
Pha Depolymerase ◽  
Medium Chain ◽  
Medium Chain Length

ABSTRACTNineteen medium-chain-length (mcl) poly(3-hydroxyalkanoate) (PHA)-degrading microorganisms were isolated from natural sources. From them, seven Gram-positive and three Gram-negative bacteria were identified. The ability of these microorganisms to hydrolyze other biodegradable plastics, such as short-chain-length (scl) PHA, poly(ε-caprolactone) (PCL), poly(ethylene succinate) (PES), and poly(l-lactide) (PLA), has been studied. On the basis of the great ability to degrade different polyesters,Streptomyces roseolusSL3 was selected, and its extracellular depolymerase was biochemically characterized. The enzyme consisted of one polypeptide chain of 28 kDa with a pI value of 5.2. Its maximum activity was observed at pH 9.5 with chromogenic substrates. The purified enzyme hydrolyzed mcl PHA and PCL but not scl PHA, PES, and PLA. Moreover, the mcl PHA depolymerase can hydrolyze various substrates for esterases, such as tributyrin andp-nitrophenyl (pNP)-alkanoates, with its maximum activity being measured withpNP-octanoate. Interestingly, when poly(3-hydroxyoctanoate-co-3-hydroxyhexanoate [11%]) was used as the substrate, the main hydrolysis product was the monomer (R)-3-hydroxyoctanoate. In addition, the genes of severalActinobacteriastrains, includingS. roseolusSL3, were identified on the basis of the peptidede novosequencing of theStreptomyces venezuelaeSO1 mcl PHA depolymerase by tandem mass spectrometry. These enzymes did not show significant similarity to mcl PHA depolymerases characterized previously. Our results suggest that these distinct enzymes might represent a new subgroup of mcl PHA depolymerases.

scholarly journals Medium Chain and Long Chain Alkanes Hydroxylase Producing Whole Cell Biocatalyst From Marine Bacteria

2018 ◽  
Vol 22 (1) ◽  
pp. 12
Author(s):  
Ahmad Thontowi ◽  
Elvi Yetti ◽  
Yopi Yopi
Keyword(s):  
Chain Length ◽  
Alkane Hydroxylase ◽  
16S Rdna Gene ◽  
Short Chain Length ◽  
Medium Chain ◽  
Medium Chain Length ◽  
Degrading Bacteria ◽  
Whole Cell Biocatalyst ◽  
Test Result ◽  
Long Chain

Alkanes are  major component of crude oil that could be hydrolyzed by the enzyme of alkane hydroxylase. The are three types of alkane hydroxylase based on the chain length of alkane such as short-chain length/SCL (C2-C4), medium-chain length/MCL (C5-C17), and long-chain length/LCL (C>18). The aims of this study were to characterize and identify alkanes-degrading bacteria from these bacteria. The 30 strains from marine were grown on MCL (Pentane-C5H12, Decane-C10H22, and Pentadecane-C15H32) and LCL (n-Paraffin-C12H19C17 and branch of Pristane-C19H40). The study showed twenty-nine isolates have the ability to degrade alkanes compounds, whereas 14 isolates have grown ability on MCL and LCL medium, 11 isolates have the ability to grow on MCL and n-LCL, 3 isolates have the ability only to grow on MCL medium and 1 isolate has the ability only grow on n-LCL medium. The growth test result indicated that 29 isolates have medium-chain alkane monooxygenase and long-chain alkane hydroxylase. Based on 16S rDNA gene analysis, we obtained twenty nine of oil- degrading bacteria, namely a-proteobacteria (57 %), g-proteobacteria (30 %), Flavobacteria (7 %), Bacilli (3%) and Propionibacteriales (3 %). g-Proteobacteria and a-proteobacteria which seems to play an important role in the alkane biodegradation.

Substrate specificities of poly(hydroxyalkanoate)-degrading bacteria and active site studies on the extracellular poly(3-hydroxyoctanoic acid) depolymerase of Pseudomonas fluorescens GK13

1995 ◽  
Vol 41 (13) ◽  
pp. 170-179 ◽  
Author(s):  
Andreas Schirmer ◽  
Claudia Matz ◽  
Dieter Jendrossek
Keyword(s):  
Pseudomonas Fluorescens ◽  
Chain Length ◽  
Active Site ◽  
Consensus Sequence ◽  
Serine Hydrolases ◽  
Short Chain Length ◽  
Substrate Specificities ◽  
Medium Chain Length ◽  
Degrading Bacteria ◽  
The Family

The isolation of poly(3-hydroxyoctanoic acid)- and poly(6-hydroxyhexanoic acid)-degrading bacteria yielded 28 strains with abilities to degrade various polymers. The most versatile strains hydrolyzed five different polyesters comprising short chain length and medium chain length poly(hydroxyalkanoates). The new isolates together with previously isolated poly(hydroxyalkanoate)-degrading bacteria were classified into 11 groups with respect to their polymer-degrading specificities. All PHA depolymerases studied so far have been characterized by the lipase consensus sequence Gly-X-Ser-X-Gly in their amino acid sequence, which is a known sequence for serine hydrolases. When we replaced the central residue, Ser-172, in the corresponding sequence Gly-Ile-Ser-Ser-Gly of the extracellular poly(3-hydroxyoctanoic acid) depolymerase of Pseudomonas fluorescens GK13, with alanine the enzyme lost its activity completely. This result of the mutational experiment indicates that the poly(3-hydroxyoctanoic acid) depolymerase belongs to the family of serine hydrolases.Key words: poly(hydroxyalkanoates), PHA depolymerases, serine hydrolases, substrate specificity, Pseudomonas fluorescens.

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