Research Articles (Microbiology)

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Browsing Research Articles (Microbiology) by Author "Ahire, Jayesh J."

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    Ciprofloxacin-eluting nanofibers inhibits biofilm formation by pseudomonas aeruginosa and a Methicillin-resistant Staphylococcus aureus
    (Public Library of Science, 2015-04) Ahire, Jayesh J.; Neveling, Deon P.; Hattingh, Melanie; Dicks, Leon Milner Theodore, 1961-; Microbiology
    Pseudomonas aeruginosa and Staphylococcus aureus are commonly associated with hospital- acquired infections and are known to form biofilms. Ciprofloxacin (CIP), which is normally used to treat these infections, is seldom effective in killing cells in a biofilm. This is mostly due to slow or weak penetration of CIP to the core of biofilms. The problem is accentuated by the release of CIP below MIC (minimal inhibitory concentration) levels following a rapid (burst) release. The aim of this study was to develop a drug carrier that would keep CIP above MIC levels for an extended period. Ciprofloxacin was suspended into poly(D,Llactide) (PDLLA) and poly(ethylene oxide) (PEO), and electrospun into nanofibers (CIP-F). All of the CIP was released from the nanofibers within 2 h, which is typical of a burst release. However, 99% of P. aeruginosa PA01 cells and 91% of S. aureus Xen 30 cells (a methicillinresistant strain) in biofilms were killed when exposed to CIP-F. CIP levels remained above MIC for 5 days, as shown by growth inhibition of the cells in vitro. The nanofibers were smooth in texture with no bead formation, as revealed by scanning electron and atomic force microscopy. A single vibration peak at 1632 cm-1, recorded with Fourier transform infrared spectroscopy, indicated that CIP remained in crystal form when incorporated into PDLLA: PEO. No abnormalities in the histology of MCF-12A breast epithelial cells were observed when exposed to CIP-F. This is the first report of the inhibition of biofilm formation by CIP released from PDLLA: PEO nanofibers.
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    Copper-containing anti-biofilm nanofiber scaffolds as a wound dressing material
    (Public Library of Science, 2016) Ahire, Jayesh J.; Hattingh, Melanie; Neveling, Deon P.; Dicks, Leon Milner Theodore, 1961-
    Copper particles were incorporated into nanofibers during the electrospinning of poly-D,L-lactide (PDLLA) and poly(ethylene oxide) (PEO). The ability of the nanofibers to prevent Pseudomonas aeruginosa PA01 and Staphylococcus aureus (strain Xen 30) to form biofilms was tested. Nanofibers containing copper particles (Cu-F) were thinner (326 ± 149 nm in diameter), compared to nanofibers without copper (CF; 445 ± 93 nm in diameter). The crystalline structure of the copper particles in Cu-F was confirmed by X-ray diffraction (XRD). Copper crystals were encapsulated, but also attached to the surface of Cu-F, as shown scanning transmission electron microscopy (STEM) and transmission electron microscopy (TEM), respectively. The copper particles had no effect on the thermal degradation and thermal behaviour of Cu-F, as shown by thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC). After 48 h in the presence of Cu-F, biofilm formation by P. aeruginosa PA01 and S. aureus Xen 30 was reduced by 41% and 50%, respectively. Reduction in biofilm formation was ascribed to copper released from the nanofibers. Copper-containing nanofibers may be incorporated into wound dressings.
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    Soymilk bio-enrichment by indigenously isolated riboflavin-producing strains of Lactobacillus plantarum
    (Elsevier, 2019-11) Bhushan, Bharat; Kumkum, C. R.; Kumari, Mamta; Ahire, Jayesh J.; Dicks, Leon M. T.; Mishra, Vijendra
    Lactobacilli (n = 68) isolated from human feces and fermented milk products were screened for the production of riboflavin (vitamin B2) by culturing into riboflavin assay medium (RAM). Cell-free culture supernatants from positive isolates (BBC32A, BBC32B, BBC33 and BIF43) were transferred onto RAM agar pre-seeded with Enterococcus faecalis MTCC2729 (a riboflavin auxotroph). The enhanced growth of B2-auxotroph confirmed the bioavailability of produced vitamin. Isolate BBC32B produced the highest riboflavin (319 ± 36 μg/l), followed by BBC33 (304 ± 91 μg/l), BBC32A (276 ± 8 μg/l) and BIF43 (257 ± 91 μg/l). All four isolates contained riboflavin genes ribG, ribB, ribA and ribH. Sequencing of DNA fragments amplified from the 16S–23S rRNA intergenic spacer region and areas flanking the 23S rRNA gene grouped these isolates within the species Lactobacillus plantarum. Identifications were confirmed by sequencing 1300-bp of amplified 16S rDNA fragments. Fermentation of soymilk by single cultures of L. plantarum BBC32B, BBC33 and BIF43 yielded 49.05%, 38.97% and 35.94% riboflavin enrichment respectively, which is more than 18.75% recorded in literature for Lactobacillus fermentum MTCC8711. Maximum levels of riboflavin were obtained within 12 h of fermentation in soymilk. Lactobacillus plantarum BBC32B may be used as starter culture for developing of riboflavin-enriched soymilk.