Occurrence of 20S RNA and 23S RNA replicons in industrial yeast strains and their variation under nutritional stress conditions

We have characterized industrial yeast strains used in the brewing, baking, and winemaking industries for the presence or absence of cytoplasmic single-stranded 20S and 23S RNAs. Furthermore, the variation of intracellular concentrations of these replicons in brewing and laboratory strains under nutritional stress conditions was determined. Our results show a correlation between the relative abundance of these replicons and exposure of yeast to nutritionally stressful conditions, indicating that these RNAs could be employed as molecular probes to evaluate the exposure of 20S(+) and/or 23S(+) yeast strains to stress situations during industrial manipulation. During this study, several 20S(-)23S(+) Saccharomyces cerevisiae strains were isolated and identified. This is the first time that a yeast strain containing only 23S RNA has been reported, demonstrating that 20S RNA is not required for 23S RNA replication.     

Screening of biogenic amine production by lactic acid bacteria isolated from grape must and wine

The potential to produce the biogenic amines tyramine, histamine and putrescine, was investigated for lactic acid bacteria (LAB) of various origin, including commercial malolactic starter cultures, type strains and 78 strains isolated from Spanish grape must and wine. The presence of biogenic amines in a decarboxylase synthetic broth was determined by reverse-phase high performance liquid chromatography (RP-HPLC). Tyramine was the main amine formed by the LAB strains investigated. Leuconostoc strains were the most intensive tyramine formers. No potential to form biogenic amines was observed in Oenococcus oeni strains. Two strains of Latobacillus buchneri were associated with putrescine formation. None of the lactic acid bacteria produced histamine. According to these in vitro results, the commercial starter bacteria analyzed did not produce histamine, tyramine and putrescine.     

Inactivation of Staphylococcus aureus in Oat and Soya Drinks by Enterocin AS‐48 in Combination with Other Antimicrobials

The presence of toxicogenic Staphylococcus aureus in foods and the dissemination of methicillin‐resistant S. aureus (MRSA) in the food chain are matters of concern. In the present study, the circular bacteriocin enterocin AS‐48, applied singly or in combination with phenolic compounds (carvacrol, eugenol, geraniol, and citral) or with 2‐nitro‐1‐propanol (2NPOH), was investigated in the control of a cocktail made from 1 methicillin‐sensitive and 1 MRSA strains inoculated on commercial oat and soya drinks. Enterocin AS‐48 exhibited low bactericidal activity against staphylococci in the drinks investigated when applied singly. The combinations of sub‐inhibitory concentrations of enterocin AS‐48 (25 μg/mL) and phenolic compounds or 2NPOH caused complete inactivation of staphylococci in the drinks within 24 h of incubation at 22 °C. When tested in oat and soya drinks stored for 7 d at 10 °C, enterocin AS‐48 (25 μg/mL) in combination with 2NPOH (5.5 mM) reduced viable counts rapidly in the case of oat drink (4.2 log cycles after 12 h) or slowly in soya drink (3.8 log cycles after 3 d). The same combined treatment applied on drinks stored at 22 °C achieved a fast inactivation of staphylococci within 12 to 24 h in both drinks, and no viable staphylococci were detected for up to 7 d of storage. Results from the study highlight the potential of enterocin AS‐48 in combination with 2NPOH for inactivation of staphylococci.     

Response of a Lactobacillus plantarum human isolate to tannic acid challenge assessed by proteomic analyses

Scope : To gain insight on the mechanisms used by intestinal bacteria to adapt and resist the antimicrobial action of dietary tannins and identify targets for tannic acid in Lactobacillus plantarum. Methods and results : A proteomic analysis of an L. plantarum human isolate exposed to the tannic acid challenge was undertaken. Tannic acid targeted proteins involved in outstanding processes for bacterial stress resistance including cyclopropanation of membrane lipids, stress response at population scale and maintenance of cell shape. To respond to this aggression, tannic acid‐misfit cells of L. plantarum challenged with tannic acid reorganized their metabolic capacity to economize energy and express proteins involved in oxidative stress defense and cell wall biogenesis, indicating that the injury incurred by tannic acid was based on oxidative damage and disruption of the cell envelope. The induction of 3‐octaprenyl‐4‐hydroxybenzoate carboxy‐lyase, which is sensitive to changes in redox conditions and involved in ubiquinone biosynthesis in other bacteria, suggests for a tannic acid‐induced redox imbalance. Conclusion : The results reveal the adaptation of a gastrointestinal isolate of L. plantarum to tannic acid and identify antibacterial targets for this dietary compound. This provides the basis for the selection of tannin‐resistant microorganisms and their use to obtain health benefits from tannin‐containing diets.     

Antibacterial agents and cystic fibrosis: synthesis and antimicrobial evaluation of a series of N-thiomethylazetidinones

The increasing emergence of multidrug-resistant microorganisms is one of the greatest challenges in the clinical management of infectious disease. New antimicrobial agents are therefore urgently required, particularly in the treatment of chronic and recurrent infections often associated with antibiotic-resistant pathogens, as in the case of cystic fibrosis (CF) patients. This study reports the antibacterial activity of a series of monocyclic β-lactams with an alkylidenecarboxyl chain or electron-withdrawing groups such as 4-OAc, 4-SAc, and 4-SO(2)Ph at the C4 position of the ring. N-Unsubstituted and N-thiomethyl derivatives were compared. A total of 33 azetidinones were tested for their activity against Gram-positive and Gram-negative bacterial clinical isolates. The combination of an N-thiomethyl group and a benzyl ester on the 4-alkylidene side chain were found to increase the potency against Gram-positive bacteria. The N-thiomethyl group clearly elevated the activity of 4-acetoxyazetidinones relative to the corresponding NH derivatives. The most active compounds showed minimum inhibitory concentration (MIC) values of 4 and 8 mg L(-1) against methicillin-resistant Staphylococcus aureus isolated from pediatric patients with CF.     

Effect of eugenol and guaiacol application on tomato aroma composition determined by headspace stir bar sorptive extraction

BACKGROUND: The present work was carried out because there is only a small amount of literature on how the volatile composition of tomatoes can be modified by the effect of exogenous substances in contact with tomato plants. This work studies how eugenol and guaiacol, either by foliar application and/or in the surrounding atmosphere, can affect the volatile composition of this fruit. An important work of this study was also conduced to validate the analytical method [headspace stir bar sorptive extraction–gas chromatography–mass spectrometry (HS‐SBSE‐GC‐MS)] to determine the composition of the volatiles in tomato. RESULTS: Analytical method validation parameters such as linearity, limit of detection, limit of quantification, and recovery proved that this method is suitable for the analysis of tomato volatiles. Their eugenol and guaiacol content changed, with an increase of 200 and 35 times, respectively, when foliar treatment was used, and an increase of 10, in both cases, when plants were in contact with the contaminated atmosphere. As consequence of the treatments other volatile compounds changed considerably. CONCLUSION: For first time, a HS‐SBSE‐GC‐MS method was successfully validated for the study of volatiles in tomatos. Results suggests that exogenous compounds in contact with the plants, such as eugenol and guaiacol, can be absorbed changing the global volatile composition of fruits, which could produce a negative or positive effect in their aroma. © 2012 Society of Chemical Industry     

Pre-bottling use of dehydrated waste grape skins to improve colour,phenolic and aroma composition of red wines

Different dehydrated waste grape skins from the juice industry were added into aged and young red wines as an innovative way of compensating for colour loss before bottling. After addition of grape skins, colour intensity of wines increased a mean 11% and a maximum of 31% with predominance of the red component. Total polyphenols mean increase was 10% with a maximum value of 20%. Analysis of low molecular weight phenolic compounds by HPLC–DAD showed a significant (p < 0.05) content increase of the bioactive compounds gallic acid, (+)-catechin, (−)-epicatechin, and (E)-resveratrol. Anthocyanins content also increased at an average of 50 mg/l. The volatile profile of wines analysed by SBSE–GC–MS was only moderately influenced by the treatments. Mixtures of dehydrated waste grape skins were useful to improve the colour and polyphenol profile of red wines, considering them a useful tool for correcting colour loss before bottling.     

Household food insecurity in Timor-Leste

Timor-Leste is among the world’s youngest and poorest countries. It suffers from seasonal food insecurity and has the third-highest stunting rate globally. Previously inadequately documented, this paper summarises recent advances in understanding household food security in Timor-Leste and the multifaceted approaches being used to overcome it. Information comes from the extensive annual surveys of the Seeds of Life (SoL) program in Timor-Leste. The hungry season prior to maize and rice harvests is the key issue in household food security in Timor-Leste. Farm households cope with the problem through crop diversification with tubers playing a lead role as grain stocks dwindle. Foraging for wild food resources, selling animals and other assets, and social networks are other coping strategies. To address seasonal food insecurity, the government has focused on rice importation and the improvement of agricultural productivity within a multi-dimensional program. Information on storage by households of the key staple, maize, indicates an improving trend in food security at the household level from 2006/2007 to 2010/2011 through a significant reduction in the percentage of ‘at risk’ households—those who grow insufficient maize for storage during the year. The current emphasis on the widespread dissemination of the new high-yielding SoL cultivars has the potential to augment these improving trends. Nevertheless this picture remains vulnerable to weather shocks—such as drought—which are anticipated to increase with climate change and it is important to build further resilience into the agricultural systems of Timor-Leste.