Guide to Authors

Guide to Author

ERRATUM

ERRATUM - The contribution of authors in the article “Aroma Evaluation of Young Chinese Merlot Wines with Denomination of Origin”,published in volume 34(1), pp 46-53

Taxonomic Status of Lactic Acid Bacteria in Wine and Key Characteristics to Differentiate Species

Oenococcus oeni is the best malolactic bacterium adapted to low pH and the high SO2 and ethanol concentrations inwine. Leuconostoc mesenteroides and Leuconostoc paramesenteroides (now classified as Weissella paramesenteroides)have also been isolated from wine. Pediococcus damnosus is not often found in wine and is considered a contaminantof high pH wines. Pediococcus inopinatus, Pediococcus parvulus and Pediococcus pentosaceus have occasionallybeen isolated from wines. Lactobacillus brevis, Lactobacillus plantarum, Lactobacillus buchneri, Lactobacillushilgardii (previously Lactobacillus vermiforme), Lactobacillus fructivorans (previously Lactobacillus trichoidesand Lactobacillus heterohiochii) and Lactobacillus fermentum have been isolated from most wines. Lactobacillushilgardii and L. fructivorans are resistant to high acid and alcohol and have been isolated from spoiled fortifiedwines. Lactobacillus vini, Lactobacillus lindneri, Lactobacillus nagelii and Lactobacillus kunkeei have been describedmore recently. The latter two species are known to cause sluggish or stuck alcoholic fermentations in wine.Although Lactobacillus collinoides and Lactobacillus mali (previously Lactobacillus yamanashiensis) decarboxylateL-malic acid, they are more often found in cider and fruit juices. Lactobacillus curvatus, Lactobacillus delbrueckii,Lactobacillus diolivorans, Lactobacillus jensenii and Lactobacillus paracasei are seldomly isolated from wines. Somestrains of Lactobacillus casei may be closer related to Lactobacillus paracasei or a distant relative, Lactobacilluszeae. Oenococcus kitaharae, isolated from compost is genetically closely related to Oenococcus oeni, but does notdecarboxylate malate, prefers higher growth pH and is phenotypically well distinguished from O. oeni. This reviewsummarises the current taxonomic status of malolactic bacteria and lists key phenotypic characteristics that maybe used to identify the species

Review: Biosensors for the detection of Escherichia coli

The supply of safe potable water, free from pathogens and chemicals, requires routine  analyses and the application of several diagnostic techniques. Apart from being  expensive, many of the detection methods require trained personnel and are often time-consuming. With drastic climate changes, severe droughts, increases in  population and pollution of natural water systems, the need to develop ultrasensitive, low-cost and hand-held, point-of-use detection kits to monitor water quality is critical. Although Escherichia coli is still considered the best indicator of water quality, cell numbers may be below detection limits, or the cells may be non-culturable and thus only detected by DNA amplification. A number of different biosensors have been developed to detect viable, dead or non-culturable microbial cells and chemicals in water. This review discusses the differences in these biosensors and evaluates the application of microfluidics in the design of ultra-sensitive nano-biosensors.Keywords: Biosensors, microfluidics, nano-biosensors, E. coli detectio

Strains of Lactobacillus plantarum in Grape Must are also Present in the Intestinal Tract of Vinegar Flies

Twenty-one lactic acid bacteria isolated from the intestinal tract of Drosophila simulans Stuvervant and nine from Merlot noir grapes were identified as L. plantarum by PCR with species-specific primers and 16S rDNA sequencing.The 30 isolates grouped into four clusters based on RAPD-PCR banding patterns, suggesting that they belong to at least four genotypic groups. Thirteen isolates from grape must and five from the flies yielded identical RAPDPCR banding patterns and grouped into one cluster, suggesting that they are descendants from the same strain.  Concluded from these results, L. plantarum (or at least descendants from a specific strain) has the ability to use vinegar flies as a host and vector to infect grape must. Further research is needed to determine the role of this specific strain in wine fermentations

Phage types of Salmonella enterica serovar Enteritidis isolated in South Africa from 1991-1995

A total of 615 strains of Salmonella enterica serovar Enteritidis (SE), received from 1991-1995 at the Onderstepoort Veterinary Institute (OVI), were phage typed. Most SE isolates (54,7%) originated from poultry followed by humans (28 ,5 %) and poultry eggs (9,6 %). Phage type 34 was the most prevalent (40,5 %) of all isolates, followed by phage type 4 (33 ,8 %). Other phage types identified were 1, 1 b, 4a, 7, 7a, 9a, 14, 24, 24var and 35 (in total 2,4 % of isolates). Most isolates of SE were received from the Western Cape Province (47,4 %) and Gauteng (22,3 %). In poultry phage type 4 was dominant, but in humans, eggs, goats, ducks, sheep, pigs and rabbits, phage type 34 was the dominant type. It appeared as if the poultry-associated epidemic of SE in South Africa that occurred from 1991-1995 originated in the Western Cape Province during 1991 amongst poultry and then spread from there to humans and eggs and then to the rest of the country, where it emerged during 1993. Results indicate that phage type 34 was the dominant phage type from 1991-1993, but during 1994-1995 its presence declined. During this latter period the presence of phage type 4 increased. This may suggest that two smaller epidemics consisting of the two different phage types might have been responsible for the epidemic that occurred from 1991-1995.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

Influence of phenolic acids on growth and inactivation of Oenococcus oeni and Lactobacillus hilgardii

Aims: To determine the effect of several wine-associated, phenolic acids on the growth and viability of strains of Oenococcus oeni and Lactobacillus hilgardii. Methods and Results: Growth was monitored in ethanol-containing medium supplemented with varying concentrations of hydroxybenzoic acids (p-hydroxybenzoic, protocatechuic, gallic, vanillic and syringic acids) and hydroxycinnamic acids (p-coumaric, caffeic and ferulic acids). Progressive inactivation was monitored in ethanolcontaining phosphate buffer supplemented in a similar manner to the growth experiments. Hydroxycinnamic acids proved to be more inhibitory to the growth of O. oeni than hydroxybenzoic acids. On the other hand, some acids showed a beneficial effect on growth of Lact. hilgardii. p-Coumaric acid showed the strongest inhibitory effect on growth and survival of both bacteria. Conclusions: Most phenolic acids had a negative effect on growth of O. oeni, for Lact. hilgardii this effect was only noted for p-coumaric acid. Generally, O. oeni was more sensitive to phenolic acid inactivation than Lact. hilgardii. Significance and Impact of the Study: Eight wine-derived, phenolic acids were compared for their effects on wine lactic acid bacteria. Results indicate that phenolic acids have the capacity to influence growth and survival parameters. The differences found between phenolic compounds could be related to their different chemical structures

Mode of action of lipid II-targeting lantibiotics

The antimicrobial action of bacteriocins from Gram-positive bacteria is based on interaction with the cytoplasmic membrane of sensitive bacteria. Models based on studies with artificial membrane systems propose that nisin forms wedge-like poration complexes in the membrane by electrostatic interaction between the positively charged C terminus of the peptide and anionic membrane phospholipids. Nisin can also permeabilise membranes via a targeted mechanism by using lipid II, the bactoprenol-bound precursor of the bacterial cell wall, as a docking molecule. Another consequence of binding with lipid II is the inhibition of peptidoglycan biosynthesis. Mersacidine and actagardine also form a complex with lipid II, but binding only blocks the incorporation of lipid II into peptidoglycan, resulting in slow cell lysis rather than pore formation. Both peptides share a conserved sequence motif with plantaricin C and pediocin PD-1, which is most probably involved in the binding of these bacteriocins to lipid II. Although pediocin PD-1 and plantaricin C may inhibit peptidoglycan biosynthesis, pore formation is rather due to electrostatic interaction between the positively charged unbridged N-terminus and anionic phospholipids in the cytoplasmic membrane of sensitive cells. In the light of increased antibiotic resistance, this review focuses on the mode of action of lantibiotics that involve lipid II, possible candidates for the development of new-generation novel antibiotic drugs. © 2005 Elsevier B.V. All rights reserved.Revie

Partial characterization of bacteriocins produced by four lactic acid bacteria isolated from regional South African barley beer

Lactobacillus paracasei subsp. paracasei ST11BR, Lactobacillus plantarum ST13BR, Lactobacillus pentosus ST151BR and Lactococcus lactis subsp. lactis ST34BR produce bacteriocins active against Lactobacillus casei, Lactobacillus sakei, Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecalis. Bacteriocin activity was not recorded after treating of the cells with NaCl at low pH, suggesting that the peptides do not adhere to the cell surface. The bacteriocins were resistant to treatment with SDS, Tween 20, Tween 80, urea and EDTA. Treatment with Triton X-100 reduced the activity of the four bacteriocins. Triton X-114 had no effect on bacteriocin ST11BR, bacteriocin ST151BR and bacteriocin ST34BR. Bacteriocin ST13BR lost all its activity after treatment with Triton X-114. The molecular size of bacteriocins ST11BR, ST13BR, ST151BR and ST34BR are 3.2 kDa, 10 kDa, 3.0 kDa and 2.9 kDa, respectively. All four bacteriocins are produced during stationary growth. No plasmids were isolated, suggesting that the genes encoding production of these bacteriocins are located on the genome.Articl

Effect of medium components on bacteriocin production by Lactobacillus pentosus ST151BR, a strain isolated from beer produced by the fermentation of maize, barley and soy flour

Lactobacillus pentosus ST151BR, isolated from home-brewed beer, produces a 3.0 kDa antibacterial peptide (bacteriocin ST151BR) active against Lactobacillus casei, Lactobacillus sakei, Pseudomonas aeruginosa, Enterococcus faecalis and Escherichia coli. Treatment with Proteinase K or Pronase resulted in loss of activity. Bacteriocin levels of 6400 AU/ml were recorded in MRSbb (De Man-Rogosa-Sharpe broth without Tween 80) at pH 5.5, 6.0 and 6.5. The same growth conditions at pH 4.5 yielded only 1600 AU/ml bacteriocin. Inclusion of Tween 80 in the growth medium reduced bacteriocin production by more than 50%. Growth in the presence of tryptone or tryptone plus meat extract stimulated bacteriocin production, whereas much lower activity was recorded when the bacteria were grown in the presence of meat extract, yeast extract, tryptone plus yeast extract, meat extract plus yeast extract, or a combination of tryptone, meat extract and yeast extract. MRSbb supplemented with maltose, lactose or mannose (2.0%, w/v) yielded bacteriocin levels of 6400 AU/ml. Sucrose or fructose at these concentrations reduced the activity by 50 and 75%, respectively. Growth in the presence of 4.0% (w/v) glucose resulted in 50% activity loss. Glycerol levels as low as 0.1% (w/v) repressed bacteriocin production. Addition of cyanocobalamin, ascorbic acid, thiamine and thioctic acid (1.0 mg/l) to the growth medium did not lead to an increase in bacteriocin production.Articl