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Polyhydroxyalkanoates： Current applications in the medical field

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Frontiers in Biology 2016年第1期11卷 19-27页

作者： Iftikhar Ali nazia jamil Microbiology and Molecular Genetics University of the Punjab Quaid-i-Azam Campus Lahore-54590 Pakistan

Polyhydroxyalkanoates （PHAs） are a class of biopolyesters that are synthesized intracellularly by microorganisms, mainly by different genera of eubacteria. These biopolymers have diverse physical and chemical properties that also classify them as biodegradable in nature and make them compatible to living systems. In the last two decades or so, PHAs have emerged as potential useful materials in the medical field for different applications owing to their unique properties. The lower acidity and bioactivity of PHAs confer them with minimal risk compared to other biopolymers such as poly-lactic acid （PLA） and poly-glycolic acid （PGA）. Therefore, the versatility of PHAs in terms of their non-toxic degradation products, biocompatibility, desired surface modifications, wide range of physical and chemical properties, cellular growth support, and attachment without carcinogenic effects have enabled their use as in vivo implants such as sutures, adhesion barriers, and valves to guide tissue repair and in regeneration devices such as cardiovascular patches, articular cartilage repair scaffolds, bone graft substitutes, and nerve guides. Here, we briefly describe some of the most recent innovative research involving the use of PHAs in medical applications. Microbial production of PHAs also provides the opportunity to develop PHAs with more unique monomer compositions economically through metabolic engineering approaches. At present, it is generally established that the PHA monomer composition and surface modifications influence cell *** synthesis by bacteria does not require the use of a catalyst （used in the synthesis of other polymers）, which further promotes the biocompatibility of PHA-derived polymers.

关键词： Biopolymers polyhydroxyalkanoates biocompatibility medical implantations

Synthesis of scl-poly （3-hydroxyalkanoates） by Bacillus cereus found in freshwater, from monosaccharides and disaccharides

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Frontiers in Biology 2018年第1期13卷 63-69页

作者： Tayyaba Naeem Naima Khan nazia jamil Department of Microbiology and Molecular Genetics University of the Punjab-Quaid-i-Azam Campus Lahore-54590 Pakistan

BACKGROUND： Polyhydroxyalkanoates are a good substitute for synthetic plastic because they are highly biocompatible, ecofriendly, and biodegradable. Bacteria in freshwater bodies such as rivers, tube wells, and canals are exposed to alternating high and low concentrations of substrates that induce PHA production. METHODS： Fresh water samples were collected for isolation of bacterial strains. Screening of PHA in bacterial cells was performed with Sudan and Nile Red staining. Extracted PHA was characterized by FTIR. RESULTS： In this study, nine bacterial isolates were selected for PHA production on the basis ofphenotypic screening. Their ability to accumulate PHAs was determined using different monosaccharides and disaccharides. Two bacterial isolates Bacillus cereus T1 （KY746353） and Bacillus cereus R3 （KY746354） produced PHAs. Optimal growth of the bacterial strain （T1） was observed in the presence of glucose, followed by maximum production of PHAs （63% PHAs） during the logarithmic phase of growth. B. cereus R3 （KY746354） accumulated 60% PHAs by dry cell weight. CONCLUSION： PHA accumulation was relatively less with fructose, but both strains showed increased production （up to 50%） with sucrose. The polymer produced was characterized by Fourier-transform infrared spectroscopy （FTIR）, which showed that the compound contains short-chain PHAs.

关键词： ecofriendly bioeompatible scl-poly (3-hydroxyalkanoates) Bacillus cereus

Biosynthesis of polyhydroxyalkanoates from styrene by Enterobacter spp. isolated from polluted environment

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Frontiers in Biology 2017年第3期12卷 210-218页

作者： Arooj Arshad Bisma Ashraf Iftikhar Ali nazia jamil Department of Microbiology and Molecular Genetics University of the Punjab Quaid-e-Azam Campus Lahore-54590 Pakistan

BACKGROUND： Styrene and its metabolites are known to have serious adverse effects on human health and hence, strategies to prevent its release, eradicate it from the environment, and understand its route of degradation are being considered. METHODS： A total of 18 strains were isolated from 4 samples of diesel contaminated soils. Among them 5 strains were selected for their ability to degrade styrene and use it as a sole carbon source to produce PHA. These strains were identified as Enterobacter spp. on the basis of 16S rRNA gene sequencing. Bacteria were screened for their ability to produce PHA by utilizing glucose and styrene as a carbon sources. Screening for PHA production was done by Nile blue A, Sudan black B, and phase contrast microscopy and the selected 3 strains showed positive results. Growth kinetics along with time profiling of PHA was performed for glucose and styrene as carbon sources. RESULTS： PHA extraction was done at equal intervals of 12 h by sodium hypochlorite method which showed that these strains accumulate maximum amount of PHA after 48 h in glucose （30.60%）. FTIR analysis of PHA was done which revealed homopolymer PHB and copolymer （PHB-co-PHV） production in strains by utilizing glucose and styrene. Gas chromatography mass spectrometry was carried out to identify the metabolites produced by bacterial strains grown on styrene. Metabolites of styrene degradation included propyne and phenylalanine. Genomic DNA isolation was carried out to amplify phaC gene which encodes PHA synthase enzyme. CONCLUSIONS： The conversion of styrene to polyhydroxyalkanoates （PHA） provides a new and unique link between an aromatic environmental pollutant and aliphatic PHA accumulation.

关键词： biodegradable polymers environmental pollutants PHA FTIR recycling bacteria

Reexamining intra and extracellular metabolites produced by Pseudomonas aeruginosa

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Journal of Coastal Life Medicine 2016年第2期4卷 132-139页

作者： Maria Shuja nazia jamil Department of Microbiology and Molecular Genetics University of the Punjab Lahore-54590Pakistan

Objective:To isolate,screen and analyze bacteria from different areas of Pakistan for the production of antimicrobial compounds,zinc solubilization and bioplastic ***:Isolation and purification was proceeding with streak plate *** assay was completed with well diffusion and thin-layer *** vivo analysis of bioplastic was analyzed with Nile blue fluorescence under UV and Sudan ***:A total of 18 bacterial strains purified from soil samples while 148 strains form stock cultures were *** of 166 only 94 showed antimicrobial activity against each of Grampositive and Gram-negative;cocci and *** case of heavy metal(ZnO and Zn_(3)(PO_(4))_(2)·4H_(2)O)solubilization,54 strains solubilized ZnO and 23 strains solubilized Zn_(3)(PO_(4))_(2)·4H_(2)O,while 127 strains grown on polyhydroxyalkanoate detection meedia supplemented with Nile blue medium showed bioplastic production by producing fluorescence under UV *** bacterial strains(coded as 100,101,104 and 111)were selected for further *** time assay showed that strains 101,104,and 111 showed inhibitory activity after 4 h of incubation while strain 100 showed after 8 *** four strains were tolerable to the maximum concentration of *** products of both 16S rRNA and PhaC gene fragments of strain 111 were sequenced and submitted to GenBank as accession numbers EU781525 and ***:Bacterial strain Pseudomonas aeruginosa-111 has potential to utilize as biofertilize and bioplastic producer.

关键词： Antimicrobial activity Solubilization Zinc Oxide Zinc Phosphate Bioplastics