Browsing by Author "Marx, Isa Jacoba"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- ItemCharacterization of plasmids isolated from Aeromonas spp. obtained from South African aquaculture systems(Stellenbosch : Stellenbosch University, 2007-03) Marx, Isa Jacoba; Chenia, H. Y.; Rawlings, D. E.; Stellenbosch University. Faculty of Science. Dept. of Microbiology.ENGLISH ABSTRACT: The plasmid content of 37 Aeromonas spp. isolates, obtained from South African tilapia, trout and koi aquaculture systems, was evaluated and 17 Aeromonas spp. isolates appeared to contain one or more plasmids ranging in size from 1 to 35 kb. Large plasmids (75-200 kb) were detected using S 1 nuclease pulsed-field gel electrophoresis in seven isolates. Twenty-three Escherichia coli transforrnants containing single/multiple plasmids from the 17 plasmid-containing isolates were characterized with respect to the transferred antimicrobial resistance phenotypes. Transforrnants displayed diverse phenotypes with the co-transfer of unrelated antibiotics. ~-lactam resistance was identified as the dominant resistance phenotype displayed by 13 transforrnants. Cotransfer of ampicillin, amoxycillin, augmentin, ceftriaxone, cefuroxime and the first generation quinolone, nalidixic acid occurred in 4 7 .8% of trans formants. Southern hybridization experiments with tetA, bla-TEM and strA-strB gene probes indicated the prevalence of the respective genes in 47.l %, 35.3% and 17.6% of the 17 plasmidcontaining Aeromonas spp., respectively. Low incidences of mobile genetic elements, i.e., Tnl 721 and inti were also detected. Analysis of the transformed plasmids' backbone DNA revealed the presence of possible broad-host-range plasmids based on their ability to replicate in the absence of host-encoded factors. Plasmids p3 l Tl and p36T2, isolated from A. sobria and A. hydrophila, respectively, were identified as potential lncQ-like plasmids based on positive hybridization signals with the repC gene from pRAS3.l, mobilization by the IncPa. plasmid RP4, and the relatively small size (14 kb). A 26.6 kb ColE-type plasmid isolated from A. sobria was characterized by the transferred resistance phenotype, endonuclease restriction mapping and partial sequencing. Failure to transfer the plasmid by conjugation indicated that this plasmid was not self-transmissible, while antibiotic susceptibility testing revealed indicated the transfer of resistance to 14 antibiotics to E. coli DH5a.. Overall, results indicated the high level of plasmid diversity and potential transfer of antibiotic resistance determinants between Aeromonas spp., emphasizing the role of plasmids and other mobile genetic elements in the dissemination of antibiotic resistance genes, especially in the aquaculture environment.
- ItemComparative secretome analysis of Trichoderma asperellum S4F8 and Trichoderma reesei Rut C30 during solid-state fermentation on sugarcane bagasse(BioMed Central, 2013-11) Marx, Isa Jacoba; Van Wyk, Niel; Smit, Salome; Jacobson, Daniel; Viljoen-Bloom, Marinda; Volschenk, HeinrichBackground: The lignocellulosic enzymes of Trichoderma species have received particular attention with regard to biomass conversion to biofuels, but the production cost of these enzymes remains a significant hurdle for their commercial application. In this study, we quantitatively compared the lignocellulolytic enzyme profile of a newly isolated Trichoderma asperellum S4F8 strain with that of Trichoderma reesei Rut C30, cultured on sugarcane bagasse (SCB) using solid-state fermentation (SSF). Results: Comparison of the lignocellulolytic enzyme profiles of S4F8 and Rut C30 showed that S4F8 had significantly higher hemicellulase and β-glucosidase enzyme activities. Liquid chromatography tandem mass spectrometry analysis of the two fungal secretomes enabled the detection of 815 proteins in total, with 418 and 397 proteins being specific for S4F8 and Rut C30, respectively, and 174 proteins being common to both strains. In-depth analysis of the associated biological functions and the representation of glycoside hydrolase family members within the two secretomes indicated that the S4F8 secretome contained a higher diversity of main and side chain hemicellulases and β-glucosidases, and an increased abundance of some of these proteins compared with the Rut C30 secretome. Conclusions: In SCB SSF, T. asperellum S4F8 produced a more complex lignocellulolytic cocktail, with enhanced hemicellulose and cellobiose hydrolysis potential, compared with T. reesei Rut C30. This bodes well for the development of a more cost-effective and efficient lignocellulolytic enzyme cocktail from T. asperellum for lignocellulosic feedstock hydrolysis.