http://hdl.handle.net/11189/5203 2026-09-03T06:42:28Z 2026-09-03T06:42:28Z Felix, JV Papathanasopoulos, MA Smith, AA von Holy, A Hastings, JW http://hdl.handle.net/11189/5208 2016-09-27T07:54:56Z 1994-01-01T00:00:00Z

Title: Characterization of leucocin B-Ta11a: a bacteriocin fromLeuconostoc carnosum Ta11a isolated from meat. Authors: Felix, JV; Papathanasopoulos, MA; Smith, AA; von Holy, A; Hastings, JW Abstract: Leuconostoc (Lc.) carnosum Ta11a, isolated from vacuum-packaged processed meats, produced a bacteriocin designated leucocin B-Ta11a. The crude bacteriocin was heat stable and sensitive to proteolytic enzymes, but not to catalase, lysozyme, or chloroform. It was active against Listeria monocytogenes and several lactic acid bacteria. Leucocin B-Ta11a was optimally produced at 25 degrees C in MRS broth at an initial pH of 6.0 or 6.5. An 8.9-MDa plasmid in Leuconostoc carnosum Ta11a hybridized to a 36-mer oligonucleotide probe (JF-1) that was homologous to leucocin A-UAL187. A 4.9-kb Sau3A fragment from a partial digest of the 8.9-MDa plasmid was cloned into pUC118. The 8.1-kb recombinant plasmid (pJF8.1) was used for sequencing and revealed the presence of two open reading frames (ORFs). ORF1 codes for a protein of 61 amino acids comprising a 37-amino-acid bacteriocin that was determined to be the leucocin B-Ta11a structural gene by virtue of its homology to leucocin A-UAL 187 (Hastings et al. 1991. J. Bacteriol 173:7491-7500). The 24-amino-acid N-terminal extension, however, differs from that of leucocin A-UAL187 by seven residues. The predicted protein of the ORF2 has 113 amino acids and is identical with the amino acid sequence of the cognate ORF of the leucocin A-UAL 187 operon.

1994-01-01T00:00:00Z Victor, TC Pretorius, GS Felix, JV Jordaan, AM van Helden, PD Eisenach, KD http://hdl.handle.net/11189/5207 2016-09-28T01:00:45Z 1996-01-01T00:00:00Z

Title: katG mutations in isoniazid-resistant strains of mycobacterium tuberculosis are not infrequent Authors: Victor, TC; Pretorius, GS; Felix, JV; Jordaan, AM; van Helden, PD; Eisenach, KD Abstract: In a recent article (7), we reported the results of mutational analysis of katG in isoniazid-resistant Mycobacterium tuberculosis strains and reached a number of conclusions, one of which was that variations in the katG gene of isoniazid-resistant isolates of M. tuberculosis are infrequent.’’ New data from our laboratory indicate that this statement is incorrect. It has been shown that deletions of the katG gene can lead to isoniazid resistance in M. tuberculosis (11), and analyses of the katG gene (1, 4, 5, 7, 9) have subsequently shown that missense mutations and small deletions in this gene are also associated with resistance to isoniazid. Similarly, it has been shown that mutations in genes such as inhA, rpoB, gyrA, gyrB, rpsL, and rrs are associated with resistance to isoniazid and other drugs (6). The single-strand conformation polymorphism (SSCP) technique was often used as an initial screen, which led to the subsequent identification of mutations by DNA sequencing.

1996-01-01T00:00:00Z Victor, TC Warren, R Butt, JL Jordaan, AM Felix, JV Venter, A Sirgel, FA Schaaf, HS Donald, PR Richardson, M Cynamon, MH http://hdl.handle.net/11189/5204 2016-09-27T06:11:14Z 1997-01-01T00:00:00Z

Title: Genome and MIC stability in mycobacterium tuberculosis and indications for continuation of use of isoniazid in multidrug-resistant tuberculosis. Authors: Victor, TC; Warren, R; Butt, JL; Jordaan, AM; Felix, JV; Venter, A; Sirgel, FA; Schaaf, HS; Donald, PR; Richardson, M; Cynamon, MH Abstract: Mycobacterium tuberculosis strains resistant to two or more of the first line antituberculosis drugs (MDR) are a serious threat to successful tuberculosis control programmes. For this retrospective study, 85 follow-up drug resistant isolates from 23 patients residing in a community with a high incidence of tuberculosis were collected and the level of in-vitro resistance to antibiotics determined quantitatively. PCR-SSCP and sequencing techniques were used to screen for gene mutations associated with resistance in 31 follow-up samples from a smaller group of eight patients. DNA fingerprint analysis was done on sequential isolates to confirm identity. Although treatment had a profound effect on changes in drug resistance patterns, the MIC for a particular agent remained constant in follow-up isolates. DNA fingerprinting and mutational analysis (14 different loci) showed that the genome of MDR strains of M. tuberculosis is relatively stable during the course of therapy. The rpoB gene was the most frequently mutated structural gene involved in drug resistance and a novel C to T mutation upstream of open reading frame (ORF)1 of the inhA operon was detected. No evidence was found of the presence of sfrain W (New York) in this group of MDR strains. The results stress the importance of confirming individuality of strains for the accurate calculation of frequencies of particular mutations associated with drug resistance, particularly in a high incidence area. Approximately one-half (47.8%) of the patients had isolates resistant to concentrations just above the critical concentration for isoniazid (MICs of 0.2–5 mg/L). Therefore, these patients and their contacts who develop primary drug-resistant tuberculosis may respond to higher dosages of treatment which could have a considerable impact on the cost and the ease of management of resistant tuberculosis.

1997-01-01T00:00:00Z Gachago, Daniela Ivala, Eunice Barnes, Veronica Gill, P Felix-Minnaar, J Morkel, Jolanda Vajat, N http://hdl.handle.net/11189/4606 2020-05-18T11:53:16Z 2014-01-01T00:00:00Z

Title: Towards the development of digital storytelling practices for use in resource-poor environments, across disciplines and with students from diverse backgrounds Authors: Gachago, Daniela; Ivala, Eunice; Barnes, Veronica; Gill, P; Felix-Minnaar, J; Morkel, Jolanda; Vajat, N Abstract: Digital storytelling has entered higher education as a pedagogical tool for enhancing students’ digital literacies in digitally saturated contexts. Increasing access to freely available software programs for video production and the ubiquity of mobile technologies have made digital storytelling viable in resource-poor environments. This article reports on an on-going project at a university of technology in South Africa employing both quantitative and qualitative research approaches, with the aim of understanding students’ perceptions of context-specific digital storytelling practices across various disciplines and student backgrounds. Bourdieu’s (1986) notions of field, habitus and capital as well as Yosso’s (2005, 70) idea of ‘community cultural wealth’ were applied to understand students’ perceptions of practices of digital storytelling that emerged from this project. The authors argue that complex technology projects, such as digital storytelling, are potentially viable in poorly-resourced environments, across disciplines and with students with diverse digital literacies and backgrounds, provided that: (1) technical barriers are lowered to the minimum and technologies are adopted that are freely available, owned by or easily accessible to students; (2) that the appropriate model is chosen based on these students’ social and cultural capital; and (3) that the community cultural wealth of students is considered in curriculum delivery.

2014-01-01T00:00:00Z