Nanofibers Offer Alternative Ways to the Treatment of Skin Infections

Injury to the skin causes a breach in the protective layer surrounding the body. Many pathogens are resistant to antibiotics, rendering conventional treatment less effective. This led to the use of alternative antimicrobial compounds, such as silver ions, in skin treatment. In this review nanofibers, and the incorporation of natural antimicrobial compounds in these scaffolds, are discussed as an alternative way to control skin infections. Electrospinning as a technique to prepare nanofibers is discussed. The possibility of using these structures as drug delivery systems is investigated

Thermophilin 13: In Silico Analysis Provides New Insight in Genes Involved in Bacteriocin Production

Bacteriocins are a large family of ribosomally synthesised proteinaceous toxins that are produced by bacteria and archaea and have antimicrobial activity against closely related species to the producer strain. Antimicrobial proteinaceous compounds are associated with a wide range of applications, including as a pathogen inhibitor in food and medical use. Among the several lactic acid bacteria (LAB) commonly used in fresh and fermented food preservation, Streptococcus thermophilus is well known for its importance as a starter culture for yoghurt and cheese. Previous studies described the bacteriocin thermophilin 13 exclusively in S. thermophilus SFi13 and the genes encoding its production as an operon consisting of two genes (thmA and thmB). However, the majority of bacteriocins possess a complex production system, which involves several genes encoding dedicated proteins with relatively specific functions. Up to now, far too little attention has been paid to the genes involved in the synthesis, regulation and expression of thermophilin 13. The aim of the present study, using in silico gene mining, was to investigate the presence of a regulation system involved in thermophilin 13 production. Results revealed the dedicated putative bacteriocin gene cluster (PBGC), which shows high similarity with the class IIb bacteriocins genes. This newly revealed PBGC, which was also found within various strains of Streptococcus thermophilus, provides a new perspective and insights into understanding the mechanisms implicated in the production of thermophilin 13

Expression of the mucus adhesion gene Mub, surface layer protein Slp and adhesion-like factor EF-TU of Lactobacillus acidophilus ATCC 4356 under digestive stress conditions, as monitored with real-time PCR

Expression of the mucus adhesion gene Mub, surface layer protein Slp and adhesion-like factor EF-Tu by Lactobacillus acidophilus ATCC 4356 grown in the presence of mucin, bile and pancreatin and at low pH was studied using real-time PCR. None of the genes were up-regulated under increasing concentrations of mucin, while Slp and EF-Tu were up-regulated in the presence of bile and pancreatin at normal concentrations (0.3%, w/v) and under stress conditions (1.0%, w/v)

Advantages and challenges of microalgae as a source of oil for biodiesel

Microalgal oil is currently being considered as a promising alternative feedstock for biodiesel. The present demand for oil for biofuel production greatly exceeds the supply, hence alternative sources of biomass are required. Microalgae have several advantages over land-based crops in terms of oil production. Their simple unicellular structure and high photosynthetic efficiency allow for a potentially higher oil yield per area than that of the best oilseed crops. Algae can be grown on marginal land using brackish or salt water and hence do not compete for resources with conventional agriculture. They do not require herbicides or pesticides and their cultivation could be coupled with the uptake of CO2 from industrial waste streams, and the removal of excess nutrients from wastewater (Hodaifa et al., 2008; An et al., 2003). In addition to oil production, potentially valuable co-products such as pigments, antioxidants, nutraceuticals, fertilizer or feeds could be produced (Mata et al., 2010; Rodolfi et al., 2009)

Optimized production of bacteriocin ST11BR, generated by Lactobacillus paracasei subsp. paracasei ST11BR isolated from traditional South African beer

CITATION: Todorov, S. D., Van Reenen, C. A. & Dicks, L. M. T. 2005. Optimized production of bacteriocin ST11BR, generated by Lactobacillus paracasei subsp. paracasei ST11BR isolated from traditional South African beer. South African Journal of Science, 101(3-4):182-186 .The original publication is available at https://journals.co.zaLittle is known about the production of antimicrobial peptides (bacteriocins) by lactic acid bacteria in traditional South African beer and their inhibition of food spoilage or pathogenic bacteria. In this paper, we report on bacteriocin ST11BR, produced by Lactobacillus paracasei subsp. paracasei ST11BR isolated from beer made with maize, barley, soy flour and sugar (sucrose). Bacteriocin ST11BR is a 3.2-kDa peptide with activity against Lactobacillus casei, L. sakei, Pseudomonas aeruginosa and Escherichia coli. The peptide is sensitive to proteinase K and pronase, but not to α-amylase. Glycerol in the growth medium repressed bacteriocin production. Tween 80 suppressed production by more than 50%, irrespective of the initial pH of the medium. MRS broth adjusted to pH 4.50 yielded 3200 AU/ml bacteriocin. The corresponding value at pH 5.0, 5.5, 6.0 and 6.5 was 12 800 AU/ml. The highest yield (25 600 AU/ml) was recorded in MRS broth without Tween 80, and with meat extract as the only nitrogen source, or a combination of meat extract and tryptone, or yeast extract and tryptone. Growth in the presence of tryptone as sole nitrogen source achieved only 12 800 AU/ml bacteriocin. Yeast extract, or a combination of yeast extract and meat extract, yielded 6400 AU/ml. A growth medium comprising 20.0 g/l maltose, sucrose or mannose yielded bacteriocin levels of 25 600 AU/ml, whereas the corresponding values for the same concentration of glucose or fructose were 12 800 AU/ml and 1 600 AU/ml, respectively. Lactose did not stimulate bacteriocin production - the highest yield (6 400 AU/ml) was generated in the presence of 10.0 g/l. No difference in bacteriocin activity was recorded when strain ST11BR was grown in the presence of 2.0 g/l KH2PO4 and 2.0-10.0 g/l K2HPO 4. However, cyanocobalamin, thiamine and DL-6,8-thioctic acid (1.0 ppm), but not L-ascorbic acid, stimulated peptide production. This study provided valuable information on the optimal production of bacteriocin by a strain of L. paracasei naturally present in a traditional beer.https://journals.co.za/content/sajsci/101/3-4/EJC96371Publisher's versio

Enhancing road verges to aid pollinator conservation: A review

Road verges provide habitats that have considerable potential as a tool for pollinator conservation, especially given the significant area of land that they collectively cover. Growing societal interest in managing road verges for pollinators suggests an immediate need for evidence-based management guidance. We used a formal, global literature review to assess evidence for the benefits of road verges for pollinators (as habitats and corridors), the potential negative impacts of roads on pollinators (vehicle-pollinator collisions, pollution, barriers to movement) and how to enhance road verges for pollinators through management. We identified, reviewed and synthesised 140 relevant studies. Overall, the literature review demonstrated that: (i) road verges are often hotspots of flowers and pollinators (well established), (ii) traffic and road pollution can cause mortality and other negative impacts on pollinators (well established), but available evidence suggests that the benefits of road verges to pollinators far outweigh the costs (established but incomplete), and (iii) road verges can be enhanced for pollinators through strategic management (well established). Future research should address the lack of holistic and large-scale understanding of the net effects of road verges on pollinators. We provide management recommendations for enhancing both individual road verges for pollinators (e.g. optimised mowing regimes) and entire road networks (e.g. prioritising enhancement of verges with the greatest capacity to benefit pollinators), and highlight three of the most strongly supported recommendations: (i) creating high quality habitats on new and existing road verges, (ii) reducing mowing frequency to 0–2 cuts/year and (iii) reducing impacts of street lighting