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Maximum biosurfactant production was achieved in an optimised process containing pH 8 and 30°C, with waste coconut oil and ammonium sulphate at carbon-to-nitrogen ratio of 1:7. The structural composition of Acinetobacter sp. V2 biosurfactant was polymeric, consisting of a protein complex and a fatty acid. This biosurfactant exhibited stability to different pH and temperature conditions. The emulsifying property was affected by changes in NaCl concentration. The V2 biosurfactant was effective in removing heavy metals present in acid mine drainage effluents and contaminated vegetables. [ABSTRACT FROM AUTHOR]

Hydrophobic pollutants remain a serious threat to animals, plants, humans, and the biological system at large if not reduced or removed from the environments. This study focused on the experimental degradation analysis of 2% each of diesel fuel and n-hexadecane utilized as a source of carbon and energy by Paenibacillus sp. D9. During the process, there was the removal of 98.4% and 61.2% n-hexadecane and diesel fuel, respectively, in the 14 days incubation period. There was involvement of degradative enzymes, namely alkane hydroxylase, alcohol dehydrogenase, and esterase as determined during the process of biodegradation. The activities of alkane hydroxylase (82 U), alcohol dehydrogenase (23 U), and esterase (0.220 U) were differentially produced, with enhanced biosurfactant activity, demonstrating their contribution to degradation of hydrocarbons. The outcomes were additionally reinforced as specific polymerase chain reaction primers were used to detect the presence of genes responsible for biodegradation and biosurfactant synthesis. The data revealed that the efficiency of the biosurfactant in accelerating the degradation and solubilization of these hydrocarbons was ensured with high hydrophobicity, emulsifying capacities, and surface tension reduction. Therefore, due to the production of enzymes, Paenibacillus sp. D9 strain was active than reported biosurfactant-producing bacteria in the biodegradation of hydrophobic pollutants. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) are sought after by many industries including food industries, heavy metal sensing, pharmaceutical, and textile. The present study reports on the biosynthesis of silver nanoparticles (AgNPs) and theirs antibacterial activity using a methanolic leaf extract of Heteropyxis natalensis, a native South African medicinal tree. The synthesised particles were characterised by ultraviolet visible spectroscopy (UV-vis), energy dispersive Xray spectroscopy (EDX), high resolution transmission electron microscopy (HRTEM), and Fourier transform infrared spectroscopy (FTIR). A colour change of the reaction solution from yellow to brown preliminarily confirmed the presence of AgNPs, and a single absorbance peak at 422 nm, using UV-vis spectroscopy, was the indicative of AgNPs. While EDX revealed the presence of elemental silver in the sample, HRTEM identified spherical AgNPs ranging from 5-60 nm. Hydroxyls, alkynes, alkenes, alkanes, esters, and alkyl halides as possible capping agents of silver ions (Ag+) into AgNPs were identified by FTIR. In addition, AgNPs exhibited antibacterial efficacy against 5 strains of pathogenic bacteria: Escherichia coli, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis. The results obtained in this study could potentially benefit future research in nanomedical-driven fields. [ABSTRACT FROM AUTHOR]

An analysis of the labeling and measurement of the enzyme RNA polymerase II revealed a conformation change in the enzyme molecule due to the binding of RNA polymerase II to DNA template. Enzyme labeling revealed a maximal specificity at a certain ATP site that was not the substrate binding site during polymerization reaction.

Abstract Background Severe Acute Respiratory Syndrome (SARS) is a severe respiratory illness caused by a novel virus, the SARS coronavirus (SARS-CoV). 3C-like protease (3CLpro) of SARS-CoV plays a role in processing viral polypeptide precursors and is responsible of viral maturation. However, the function of 3CLpro in host cells remains unknown. This study investigated how the 3CLpro affected the secretion of cytokines in the gene-transfected cells. Results From immunofluorescence microscopy, the localization of c-myc tagged 3CLpro was detected both in the cytoplasm and nucleus of transfected A549 cells. Expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) was significantly decreased in 3CLpro-transfected cells by both RT-PCR and ELISA, but without changes in other cytokines, i.e., IL-1β, IL-6, IL-8, IL12p40, TNF-α, and TGF-β. Furthermore, the protein levels of NF-kB decreased in 3CLpro-transfected A549 cells when compared to EGFP transfected cells. Conclusions Our results suggest that the 3CLpro may suppress expression of GM-CSF in transfected A549 cells through down-regulation of NF-kB production.

Abstract Background Mupirocin is a topical antimicrobial agent which is used for the treatment of skin and postoperative wound infections, and the prevention of nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA). However, the prevalence of mupirocin resistance in S. aureus, particularly in MRSA, has increased with the extensive and widespread use of this agent in hospital settings. This study characterized low- and high-level mupirocin-resistant S. aureus isolates obtained from Nigeria and South Africa. Methods A total of 17 mupirocin-resistant S. aureus isolates obtained from two previous studies in Nigeria and South Africa, were characterized by antibiogram, PCR-RFLP of the coagulase gene and PFGE. High-level mupirocin resistant isolates were confirmed by PCR detection of the mupA gene. The genetic location of the resistance determinants was established by curing and transfer experiments. Results All the low-level mupirocin resistant isolates were MRSA and resistant to gentamicin, tetracycline and trimethoprim. PFGE identified a major clone in two health care institutions located in Durban and a health care facility in Pietermaritzburg, Greytown and Empangeni. Curing and transfer experiments indicated that high-level mupirocin resistance was located on a 41.1 kb plasmid in the South African strain (A15). Furthermore, the transfer of high-level mupirocin resistance was demonstrated by the conjugative transfer of the 41.1 kb plasmid alone or with the co-transfer of a plasmid encoding resistance to cadmium. The size of the mupirocin-resistance encoding plasmid in the Nigerian strain (35 IBA) was approximately 35 kb. Conclusion The emergence of mupirocin-resistant S. aureus isolates in Nigeria and South Africa should be of great concern to medical personnel in these countries. It is recommended that methicillin-susceptible S. aureus (MSSA) and MRSA should be routinely tested for mupirocin resistance even in facilities where the agent is not administered. Urgent measures, including judicious use of mupirocin, need to be taken to prevent clonal dissemination of the mupirocin/methicillin resistant S. aureus in KZN, South Africa and the transfer of the conjugative plasmid encoding high-level mupirocin resistance identified in this study.

Abstract Background Antimicrobial resistance of Staphylococcus aureus especially methicillin-resistant S. aureus (MRSA) continues to be a problem for clinicians worldwide. However, few data on the antibiotic susceptibility patterns of S. aureus isolates in South Africa have been reported and the prevalence of MRSA in the KwaZulu-Natal (KZN) province is unknown. In addition, information on the characterization of S. aureus in this province is unavailable. This study investigated the susceptibility pattern of 227 S. aureus isolates from the KZN province, South Africa. In addition, characterization of methicillin-sensitive S. aureus (MSSA) and MRSA are reported in this survey. Methods The in-vitro activities of 20 antibiotics against 227 consecutive non-duplicate S. aureus isolates from clinical samples in KZN province, South Africa were determined by the disk-diffusion technique. Isolates resistant to oxacillin and mupirocin were confirmed by PCR detection of the mecA and mup genes respectively. PCR-RFLP of the coagulase gene was employed in the characterization of MSSA and MRSA. Results All the isolates were susceptible to vancomycin, teicoplanin and fusidic acid, and 26.9% of isolates studied were confirmed as MRSA. More than 80% of MRSA were resistant to at least four classes of antibiotics and isolates grouped in antibiotype 8 appears to be widespread in the province. The MSSA were also susceptible to streptomycin, neomycin and minocycline, while less than 1% was resistant to chloramphenicol, ciprofloxacin, rifampicin and mupirocin. The inducible MLSB phenotype was detected in 10.8% of MSSA and 82% of MRSA respectively, and one MSSA and one MRSA exhibited high-level resistance to mupirocin. There was good correlation between antibiotyping and PCR-RFLP of the coagulase gene in the characterization of MRSA in antibiotypes 1, 5 and 12. Conclusion In view of the high resistance rates of MRSA to gentamicin, erythromycin, clindamycin, rifampicin and trimethoprim, treatment of MRSA infections in this province with these antibacterial agents would be unreliable. There is an emerging trend of mupirocin resistance among S. aureus isolates in the province. PCR-RFLP of the coagulase gene was able to distinguish MSSA from MRSA and offers an attractive option to be considered in the rapid epidemiological analysis of S. aureus in South Africa. Continuous surveillance on resistance patterns and characterization of S. aureus in understanding new and emerging trends in South Africa is of utmost importance.

The aim of this study was to purify and characterize α-amylase of Paenibacillus species D9 and cloned α-amylase in Escherichia coli transformants. Optimal growth and production of D9 α-amylase were obtained after the 24-h incubation period, at pH 7, 30 °C and 200 rpm, using starch as the sole carbon source. Sodium nitrate stimulated α-amylase production by 3 folds while urea had an inhibitory effect comparing with yeast extract as the control. Characterization results of the crude and purified enzyme were similar. Purified D9 α-amylase possessed 97% residual activity after incubation at 30 °C for 120 min while 50% at 45 °C and 27% at 60 °C, respectively, under the same condition. The presence of Ca2+ ions enhanced the activity, while EDTA and Fe3+ had an inhibitory effect. Kinetic parameters were obtained having values of 37.3 mM, 19.8 U/mg and 4.84 s−1 for Km, Vmax and kcat, respectively. The α-amylase gene (amyS) of Paenibacillus sp. D9 was amplified using polymerase chain reaction (1482 bp), cloned into PSF-OXB20 vector and expressed in E. coli BL21 DE3 (pLysS) after transformation. The α-amylase purified from the transformant using a Hispur Cobalt column possessed 1.4 folds (450.8 U/mg) higher specific activity than the purified α-amylase from the wild type. Cloned α-amylase was more thermostable at 45 °C and at 60 °C, but less pH stable at pH 5 and 6. All other biochemical properties of the native and recombinant α-amylase show no significant differences. In conclusion, α-amylase of Paenibacillus sp. D9 was purified, cloned and characterized. The potential biotechnological application(s) of α-amylase may be explored. [ABSTRACT FROM AUTHOR]