Antimicrobial peptides (AMPs) are promising novel antibiotics since they have shown antimicrobial activity against a wide range of bacterial species, including multiresistant bacteria; however, ...toxicity is the major barrier to convert antimicrobial peptides into active drugs. A profound and proper understanding of the complex interactions between these peptides and biological membranes using biophysical tools and model membranes seems to be a key factor in the race to develop a suitable antimicrobial peptide therapy for clinical use. In the search for such therapy, different combined approaches with conventional antibiotics have been evaluated in recent years and demonstrated to improve the therapeutic potential of AMPs. Some of these approaches have revealed promising additive or synergistic activity between AMPs and chemical antibiotics. This review will give an insight into the possibilities that physicochemical tools can give in the AMPs research and also address the state of the art on the current promising combined therapies between AMPs and conventional antibiotics, which appear to be a plausible future opportunity for AMPs treatment.
Argentina is the fifth world-wide wine producer, with an area of emerging importance in the Southwest of Buenos Aires Province, where climatic conditions are rather challenging. We studied the ...variations in soil and wine bacterial diversity through three consecutive vintages, and how climatic conditions affected said diversity. During the years of our study there were two harsh climatic events, a prolonged drought that extended over two vegetative periods, and an unseasonable spring frost in 2017. We found that the bacterial diversity reacted to these climatic events, given that there was a shift in the taxa exclusive to soil and wine, and shared by both, through time. Our results show a core of microorganisms in soil as well as in wine, belonging to different phyla that are conserved across the vintage years. A trend to an enrichment in
Actinobacteria
was detected in soil samples, whereas a high relative abundance of the
Acetobacteraceae
family and a scarcity of Lactic Acid Bacteria (LAB) were detected in the wine samples. We believe our results contribute to a better understanding of the impact of climatic conditions on the soil and wine microbiota, and can provide vintners with valuable knowledge for improving their wine production.
Soil microbiomes, as a primary reservoir for plant colonizing fungi and bacteria, play a major role in determining plant productivity and preventing invasion by pathogenic microorganisms. The use of ...16S rRNA and ITS high-throughput amplicon sequencing for analysis of complex microbial communities have increased dramatically in recent years, establishing links between wine specificity and, environmental and viticultural factors, which are framed into the elusive terroir concept. Given the diverse and complex role these factors play on microbial soil structuring of agricultural crops, the main aim of this study is to evaluate how external factors, such as vintage, vineyard location, cultivar and soil characteristics, may affect the diversity of the microbial communities present. Additionally, we aim to compare the influence these factors have on the structuring of bacterial and fungal populations associated with Malbec grapevine rhizosphere with that of the more widespread Cabernet Sauvignon grapevine cultivar. Samples were taken from Malbec and Cabernet Sauvignon cultivars from two different vineyards in the San Juan Province of Argentina. Total DNA extracts from the rhizosphere soil samples were sequenced using Illumina's Miseq technology, targeting the V3-V4 hypervariable 16S rRNA region in prokaryotes and the ITS1 region in yeasts. The major bacterial taxa identified were Proteobacteria, Bacteroidetes and Firmicutes, while the major fungal taxa were Ascomycetes, Basidiomycetes, Mortierellomycetes and a low percentage of Glomeromycetes. Significant differences in microbial community composition were found between vintages and vineyard locations, whose soils showed variances in pH, organic matter, and content of carbon, nitrogen, and absorbable phosphorus.
The aim of this work was to obtain freeze-dried biomass of the native Patagonian
Lactiplantibacillus plantarum
strain UNQLp 11 from a whey permeate (WP)-based medium and compare it with the growth in ...commercial MRS broth medium. Survival and activity of the freeze-dried
Lb. plantarum
strain were investigated after inoculation in wine as a starter culture for malolactic fermentation (MLF). The effect of storage and rehydration condition of the dried bacteria and the nutrient supplementation of wine were also studied. The freeze-dried cultures from WP and those grown in MRS showed similar survival results. Rehydration in MRS broth for 24 h and the addition of a rehydration medium to wine as nutrient supplementation improved the survival under wine harsh conditions and guaranteed the success of MLF. Storage at 4 °C under vacuum was the best option, maintaining high cell viability for at least 56 days, with malic acid consumption higher than 90% after 7 days of inoculation in a wine-like medium. These results represent a significant advance for sustainable production of dried malolactic starter cultures in an environmentally friendly process, which is low cost and easy to apply in winemaking under harsh physicochemical conditions.
Graphic Abstract
Winemaking is a complex process involving two successive fermentations: alcoholic fermentation, by yeasts, and malolactic fermentation (MLF), by lactic acid bacteria (LAB). During MLF, LAB can ...contribute positively to wine flavor through decarboxylation of malic acid with acidity reduction and other numerous enzymatic reactions. However, some microorganisms can have a negative impact on the quality of the wine through processes such as biogenic amine production. For these reasons, monitoring the bacterial community profiles during MLF can predict and control the quality of the final product. In addition, the selection of LAB from a wine-producing area is necessary for the formulation of native malolactic starter cultures well adapted to local winemaking practices and able to enhance the regional wine typicality. In this sense, molecular biology techniques are fundamental tools to decipher the native microbiome involved in MLF and to select bacterial strains with potential to function as starter cultures, given their enological and technological characteristics. In this context, this work reviews the different molecular tools (both culture-dependent and -independent) that can be applied to the study of MLF, either in bacterial isolates or in the microbial community of wine, and of its dynamics during the process.
Antibiotic resistance is one of the main problems concerning public health or clinical practice. Antimicrobial peptides appear as good candidates for the development of new therapeutic drugs. In this ...study we de novo designed a group of cationic antimicrobial peptides, analyzed its physicochemical properties, including its structure by circular dichroism and studied its antimicrobial properties against a panel of clinical isolates expressing different mechanisms of resistance. Three cationic alpha helical peptides exhibited antimicrobial activity comparable to, or even better than the comparator omiganan (MBI-226).
De novo designed alpha helical cationic peptides with antimicrobial activity against multi-resistant clinical isolates. Display omitted
•De novo designed cationic peptides.•Physicochemical properties of peptides.•Antimicrobial resistant bacteria.
The malolactic fermentation (MLF) of Patagonian Malbec wine inoculated with blend cultures of selected native strains of
and
was monitored during 14 days, analyzing the strains ability to modify the ...content of some organic acids and to change the volatile compounds profile. The performance of the LAB strains was tested as single and blends cultures of both species. An implantation control by RAPD PCR was also carried out to differentiate among indigenous and inoculated strains. The
strains UNQLp11 and UNQLp155 and the
strain UNQOe73.2 were able to remain viable during the monitoring time of MLF, whereas the
strain UNQOe31b showed a decrease of five log CFU at day 14. The four strains assayed showed a similar behavior in wine whether they were inoculated individually or as blend cultures. All strains were able to consume L-malic acid, particularly the
strains, which showed the highest consumption values at day 14, both as single or blend cultures. The changes in the volatile compounds profile of Malbec wine samples, before and after MLF, were determined by HS-SPME and GC-MS technique. Wines inoculated with blend cultures containing strain UNQLp155 showed a decrease in the total alcohols content and an increase in the total esters content. On the other hand, wines inoculated with single cultures of strains UNQLp155, UNQOe31b or UNQOe73.2 showed no significant decrease in the total alcohols concentration but a significant increase in the total esters content. When strain UNQLp11 was inoculated as single or as blend culture with strain UNQOe31b, wines exhibited an increase in the total alcohols content, and a decrease in the total esters content. The content of diethyl succinate showed the greatest increase at final of MLF, and a particular synergistic effect in its synthesis was observed with a blend culture of strains UNQLp155 and UNQOe73.2. These results suggest that the use of blend cultures formulated with strains belonging to
and
species could offer an interesting advantage to induce MLF in Malbec wines, contributing to diversify their aromatic profiles.
Malolactic fermentation (MLF) is a process in winemaking responsible for the conversion of l-malic acid to l-lactic acid and CO2, which reduces the total acidity, improves the biological stability, ...and modifies the aroma profile of wine. MLF takes place during or after alcoholic fermentation and is carried out by one or more species of lactic acid bacteria (LAB), which are either present in grapes and cellars or inoculated with malolactic starters during the winemaking process. Although the main bacterium among LAB used in commercial starter cultures for MLF has traditionally been Oenococcus oeni, in the last decade, Lactobacillus plantarum has also been reported as a malolactic starter, and many works have shown that this species can survive and even grow under harsh conditions of wine (i.e., high ethanol content and low pH values). Furthermore, it has been proved that some strains of L. plantarum are able to conduct MLF just as efficiently as O. oeni. In addition, L. plantarum exhibits a more diverse enzymatic profile than O. oeni, which could play an important role in the modification of the wine aroma profile. This enzymatic diversity allows obtaining several starter cultures composed of different L. plantarum biotypes, which could result in distinctive wines. In this context, this review focuses on showing the relevance of L. plantarum as a MLF starter culture in winemaking.
How to cite: Brizuela NS, Tymczyszyn E, Semorile LC, et al. Lactobacillus plantarum as a malolactic starter culture in winemaking: a new (old) player? Electron J Biotechnol 2019;38. https://doi.org/10.1016/j.ejbt.2018.12.002.
The by-products of the food industry are an economic alternative as a source of nutrients to obtain biomass. At the same time, theiruse could solve the environmental problem related to their ...disposal, which is highly polluting due to their elevated biochemical oxygen demand. In this work, we seek to optimize the production of cellular biomass of two native Patagonian strains of Lactiplantibacillus plantarum (UNQLp 11 and UNQLp155), selected for its oenological and technological properties, using apple pomace (AP), a residue from the juice and cider industry. The supplementation of AP with yeast extract, salts, and Tween 80 (sAP), proved to maintain the growth of the Lpb. plantarum strains, similar to the commercial medium used to grow LAB (De Man, Rogosa, Sharpe, MRS). Cultures grown in sAP medium showed good tolerance to wine conditions (high ethanol content and low pH), demonstrated by its ability to consume L-malic acid. The subsequent inoculation of these cultures in sterile wines (Merlot and Pinot noir) was carried out at laboratory scale, evaluating cell viability and L-malic acid consumption for 21 days at 21 °C. Cultures grown in sAP media showed a similar performance to MRS media. Thus, sAP media proved to be a suitable substrate to grow oenological Lpb. plantarum strains where cultures (with high size inoculums) were able to drive malolactic fermentation, with an L-malic acid consumption higher than 90%.
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