0000000001212238
AUTHOR
Isabel Pardo
showing 39 related works from this author
Yeast-Bacteria Coinoculation
2019
Abstract Yeasts and lactic acid bacteria (LAB) coinoculation is the simultaneous, or close in time inoculation, of both types of microorganisms in winemaking. Coinoculation has been used mainly to early accomplish malolactic fermentation (MLF), employing generally the couples Oenococcus oeni/Saccharomyces cerevisiae and Lactobacillus plantarum/S. cerevisiae. Early completion of MLF decreases the overall vinification time, reduces the microbial spoilage risk, and even prevents the biogenic amines synthesis. LAB/yeasts coinoculation could be also used to increase the acidity of wines when inoculated in grape must, using sugar to synthesize lactic acid and producing ethanol diminution. Coinocu…
A novel culture medium for Oenococcus oeni malolactic starter production
2015
Malolactic fermentation is essential in wine quality. One of the strategies used to control this fermentation involves the inoculation of selected lactic acid bacteria, mainly Oenococcus oeni. Laboratory media usually produce large amounts of biomass, but with little or no adaptability to wine. We propose a culture medium to grow and pre-adapt O. oeni cells, and the steps to scale-up production. To achieve this objective, 27 different media were tested. All contained grape must and wine, and nutritional supplements in order to benefit bacterial growth. Those media contained different ethanol levels, pH values, and grape must concentrations. The optimized culture medium named Oenococcus Prod…
Ability of Kocuria varians LTH 1540 To Degrade Putrescine: Identification and Characterization of a Novel Amine Oxidase.
2015
This work describes the identification and characterization of an amine oxidase from Kocuria varians LTH 1540 (syn. Micrococcus varians) primarily acting on putrescine. Data from MALDI-TOF MS/MS and the identification of Δ(1)-pyrroline as degradation product from putrescine indicate that the enzyme is a flavin-dependent putrescine oxidase (PuO). Properties of partially purified enzyme have been determined. The enzyme oxidizes diamines, putrescine and cadaverine, and, to a lesser extent, polyamines, such as spermidine, but not monoamines. The kinetic constants (Km and Vmax) for the two major substrates were 94 ± 10 μM and 2.3 ± 0.1 μmol/min·mg for putrescine and 75 ± 5 μM and 0.15 ± 0.02 μmo…
Immobilisation of yeasts on oak chips or cellulose powder for use in bottle-fermented sparkling wine
2019
[EN] Sparkling wine production comprises two successive fermentations performed by Sacharomyces cerevisiae strains. This research aimed to: develop yeast immobilisation processes on two wine-compatible supports; study the effects of yeast type (IOC 18-2007 and 55A) and the immobilisation support type (oak chips and cellulose powder) on the fermentation kinetics, the deposition rate of lees and the volatile composition of the finished sparkling wine; compare the fermentation parameters of the wines inoculated with immobilised or non-immobilised cells. Proper immobilisation of yeast on oak chips and cellulose powder was demonstrated by electron microscopy. Total sugar consumption occurred in …
Influence of yeast strains on managing wine acidity using Lactobacillus plantarum
2018
Abstract Lactobacillus plantarum has been used for deacidifying wines through malolactic fermentation (MLF), and more recently for acidifying them. The species Oenococcus oeni is mainly responsible for MLF in wines at a pH below 3.5. However, the Lactobacillus and Pediococcus species can carry out this reaction in wines at a higher pH. MLF generally begins once yeasts have completed alcoholic fermentation, but nowadays some winemakers prefer carrying out MLF simultaneously to alcoholic fermentation. The advantages of this strategy are shorter times in which to complete wine vinification and better wine color stabilization. Lactobacillus plantarum is preferred to O. oeni for performing early…
Biogenic amines in wines from three Spanish regions.
2005
One hundred and sixty-three wines from La Rioja, Utiel-Requena, and Tarragona were analyzed to determine if there were any differences in the concentrations of six biogenic amines that are found in these three regions. The influence of grape variety, type of vinification, wine pH, malolactic fermentation, and storage in bottle on biogenic amine concentrations was studied. Results show important differences in putrescine and histamine concentrations among regions, varieties of grape, and type of wine; differences were less appreciable for the remaining biogenic amines studied. Low pH prevented biogenic amine formation. Malolactic fermentation and short storage periods in bottle (3-6 months) …
The effects of freezing and freeze-drying ofOenococcus oeniupon induction of malolactic fermentation in red wine
2000
Summary The use of Oenococcus oeni starter cultures for the induction of malolactic fermentation (MLF) in wine permits control over the timing of the process and the quality of the wine. Successful inoculation of bacterial starter cultures into wine depends on the selection of suitable strains and on the preparation and conservation of those cultures. Medium for Leuconostoc oenos (MLO) is the best medium for easy and rapid growth of O. oeni cultures under laboratory controlled conditions for isolation and identification. However, this study showed that O. oeni cells inoculated in MLO failed to induce MLF in wine while cells grown in Medium of Preculture (MP) or wine, stored at −20 °C or fre…
Conjugative plasmid pIP501 undergoes specific deletions after transfer from Lactococcus lactis to Oenococcus oeni
2003
Conjugal transfer of plasmids pIP501 and its derivative pVA797 from Lactococcus lactis to Oenococcus oeni was assayed by filter mating. Plasmid pIP501 was transferred to a number of O. oeni strains whereas a single transconjugant of O. oeni M42 was recovered when pVA797 was used. Physical analysis of the transconjugant plasmids revealed that pIP501 and pVA797 underwent extensive deletions in O. oeni that affected the tra region (conjugal transfer) and SegB region (stability). All derivatives showed segregational instability in O. oeni, but were stably maintained in L. lactis. These differences correlated with the different plasmid copy numbers and the extent of deletions within the SegB reg…
Lactobacillus aquaticus sp. nov., isolated from a Korean freshwater pond.
2009
A Lactobacillus strain, IMCC1736T, was isolated recently from a Korean freshwater pond following an extensive study of the microbial community in this ecosystem. Its 16S rRNA gene was sequenced and phylogenetic analysis placed this strain within the Lactobacillus salivarius group, closely related to Lactobacillus satsumensis NRIC 0604T, with 97.9% sequence similarity. In the present work, the taxonomic status of strain IMCC1736T has been re-evaluated. It was characterized phylogenetically, genotypically and phenotypically and, based on DNA-DNA hybridization values, this strain represents a novel Lactobacillus species. Strain IMCC1736T can be differentiated genotypically from its closest rel…
NAD(P)H regeneration is the key for heterolactic fermentation of hexoses in Oenococcus oeni
2002
Oenococcus oeni (formerly Leuconostoc oenos) can perform malolactic fermentation, converting L-malate to L-lactate and carbon dioxide, in wines. The energy and redox potential required to support the growth of the micro-organism are supplied mainly by the consumption of carbohydrates via the heterolactic pathway. In the first steps of hexose metabolism two molecules of NAD(P)(+) are consumed, which must be regenerated in later reactions. The aim of this work was to test if aerobic growth of O. oeni promotes higher cell yields than anaerobic conditions, as has been shown for other lactic acid bacteria. O. oeni M42 was found to grow poorly under aerobic conditions with glucose as the only car…
Improved detection and enumeration of yeasts in wine by Cells-qPCR
2018
Abstract Quantitative PCR by directly sampling (Cells-qPCR) has been adapted to detect and quantify total yeasts, and B. bruxellensis, S. cerevisiae and Z. bailii species, in grape musts and wines. To increase assay sensitivity, the effects of a previous cell wall lysis, by both enzymatic and mechanical methods, were evaluated. Cell wall disruption by mechanical methods showed the best results to enhance assay sensitivity. Numerous standard curves were constructed by mechanically lysed cells in culture medium, and in white and red grape musts and wines. Good regression values (>0.99) and efficiencies (>0.99) were obtained, and it was possible to detect one single cell per reaction in all th…
Tyramine and phenylethylamine production among lactic acid bacteria isolated from wine.
2007
The ability of wine lactic acid bacteria to produce tyramine and phenylethylamine was investigated by biochemical and genetic methods. An easy and accurate plate medium was developed to detect tyramine-producer strains, and a specific PCR assay that detects the presence of tdc gene was employed. All strains possessing the tdc gene were shown to produce tyramine and phenylethylamine. Wines containing high quantities of tyramine and phenylethylamine were found to contain Lactobacillus brevis or Lactobacillus hilgardii. The main tyramine producer was L. brevis. The ability to produce tyramine was absent or infrequent in the rest of the analysed wine species.
The use of core-shell high-performance liquid chromatography column technology to improve biogenic amine quantification in wine
2015
BACKGROUND HPLC column technology has been improved, providing better resolution of closely eluting compounds, better analyte sensitivity, and shorter analysis times. The core-shell technology columns offer a faster analysis through the use of shorter columns without compromising resolution. The aim of this work was to improve the methods for determination of biogenic amines (BAs) in wine using the new HPLC PFP core-shell column technology. RESULTS Two different elution programs were designed to quantify BAs with the core-shell PFP column. Program I flow rate was 2 mL min−1. The total elution time was 10 min. In elution program II, the flow rate was 0.8 mL min−1 and the total elution time w…
Nucleotide sequence of plasmid p4028, a cryptic plasmid from Leuconostoc oenos.
1996
Abstract TheLeuconostoc oenosplasmid p4028 was cloned in pBlueScript (SK+), and its complete nucleotide sequence was determined. The analysis of the nucleotide sequence revealed five open reading frames, all of them located on the same strand and grouped in two clusters separated by a short noncoding stretch. A similarity search against the other sequences deposited in the EMBL and GenBank databases showed that p4028 has no significant similarity with any of the sequences checked. Nevertheless, a putative ATP-binding motif was found in ORF2. A more detailed analysis of this ORF suggests that it could encode for a DNA-dependent ATPase.
The potential of positively-charged cellulose sponge for malolactic fermentation of wine, using Oenococcus oeni
2001
Malolactic fermentation (MLF) is a secondary bioconversion developed in some wines involving malic acid decarboxylation. The induction of MLF in wine by cultures of free and immobilized Oenococcus oeni cells was investigated. This work reports on the effect of surface charges in the immobilization material, a recently described fibrous sponge, as well as the pH and the composition of the media where cells are suspended. A chemical treatment provided positive charge to the sponges (DE or DEAE) and gave the highest cell loadings and subsequent resistance to removal. Preculture media to grow the malolactic bacteria before the immobilization procedure were also evaluated. We have established fa…
16S-ARDRA, a tool for identification of lactic acid bacteria isolated from grape must and wine.
2003
Lactic acid bacteria (LAB) are found in a great variety of habitats, including grape must and wines. There is a close relationship between the species of LAB which develop during fermentation and the eventual quality of the wine. For these reasons analytical techniques allowing fast and reliable identification of wine LAB are needed. In this work a simple and accurate protocol for identifying species of LAB isolated from grape must and wine is presented. This protocol is based on the amplification, directly from colony, of 16S rDNA and later digestion with one of the following restriction enzymes BfaI, MseI and AluI. A sequential use of the three enzymes is proposed to simplify LAB wine ide…
Lactobacillus uvarum sp. nov. - A new lactic acid bacterium isolated from Spanish Bobal grape must
2008
Five strains isolated from grape musts in Spain in 1997, have been characterized by several molecular techniques, and three of them have been identified as pertaining to a new species. All strains are Gram-positive rods, aerotolerant and homofermentative bacteria that do not exhibit catalase activity. Phylogenetic analysis based on 16S rRNA gene sequences placed these strains within the genus Lactobacillus, closely related to Lactobacillus mali. DNA-DNA hybridization experiments confirmed that strain 71 belongs to the lately described species L. satsumensis, strain 88 belongs to L. mali and the other three isolates have an independent status at species level. Restriction analysis of the amp…
Lactobacillus oeni sp. nov., from wine.
2009
Ten Lactobacillus strains, previously isolated from different Bobal grape wines from the Utiel-Requena Origin Denomination of Spain, were characterized phylogenetically, genotypically and phenotypically. The 16S rRNA genes were sequenced and phylogenetic analysis showed that they form a tight phylogenetic clade that is closely related to reference strains Lactobacillus satsumensis NRIC 0604T, ‘Lactobacillus uvarum’ 8 and Lactobacillus mali DSM 20444T. DNA–DNA hybridization results confirmed the separation of the strains from other Lactobacillus species. Genotypically, the strains could be differentiated from their closest neighbours by 16S amplified rDNA restriction analysis and random ampl…
Acetobacter musti sp. nov., isolated from Bobal grape must
2016
An acetic acid bacterium (strain Bo7T), obtained during a study of the microbial diversity of spontaneous fermentations of Bobal grape must, was subjected to a taxonomic study using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences allocated strain Bo7T to the genus Acetobacter, and revealed Acetobacter aceti and Acetobacter oeni to be nearest neighbours (99.57 % 16S rRNA gene sequence similarity between strain Bo7T and A. oeni CECT 5830T, and 98.76 % between strain Bo7T and A. aceti CECT 298T). Cells of strain Bo7T are Gram-negative, motile rods, catalase-positive and oxidase-negative. The DNA G+C content of strain Bo7T was 58.0 mol%. DNA–DNA hybridizations demo…
A new fear in wine: Isolation of Staphylococcus epidermidis histamine producer
2016
Abstract Biogenic amines (BAs) are undesirable compounds in all foods and beverages because they may induce food-borne intoxications when consumed at high concentrations. The aim of this study was to identify the organism responsible for the synthesis of histamine in a Tempranillo red wine from Ribera de Duero D.O. (Denomination of origin), Spain. Bacteria present in wines after malolactic fermentation were isolated, identified and typed. Four strains of the species Oenococcus oeni and two strains of Staphylococcus epidermidis were found. None of the O. oeni strains produced histamine, cadaverine or putrescine, but one of the S. epidermidis strains (Pa) was able to produce all three in synt…
Selection of Lactobacillus strains to induce biological acidification in low acidity wines
2016
Abstract Because of global warming, wines are obtained nowadays with high pH values and low acidity. This results in wines with disturbed flavor and increased susceptibility of microbial spoilage. The aim of this work was the selection of Lactobacillus strains with ability to induce biological acidification in low acidity grape musts to obtain more acidic wines. A screening of Lactobacillus strains was carried out using several selection criteria. Lactobacillus strains that grew in must, carried out the malolactic fermentation, acidified grape must, synthesized lactic acid from sugars, and showed high resistance to lysozyme and sulfur dioxide were selected. Selected strains were characteriz…
Transposons Tn916 and Tn925 can transfer from Enterococcus faecalis to Leuconostoc oenos
1996
The streptococcal transposons Tn916 and Tn925 were transferred to several strains of Leuconostoc (Ln.) oenos using the filter mating method. The insertion of both transposons into the chromosome occurred at different sites. Transconjugants of Ln. oenos carrying Tn916 could serve as donors in mating experiments with Lactococcus lactis LM2301. Further analysis of L. lactis LM2301 transconjugants showed that the insertion of the transposon Tn916 into the chromosome was site-specific. These studies establish a basis for the initiation of genetic studies in this Leuconostoc species since there are no efficient conjugal or transformation systems previously described for this microorganism.
Ochratoxin A removal in synthetic media by living and heat-inactivated cells of Oenococcus oeni isolated from wines
2010
The capacity of Oenococcus oeni to eliminate ochratoxin A (OTA) from synthetic media in different conditions was studied. Ten tested O. oeni strains removed OTA from the medium but with significant differences depending on the strain, incubation period, and initial OTA level in the medium. Mycotoxin reductions higher than 60% were recorded in 14-day cultures spiked with 2 mu g OTA/l. Toxin removal was independent of bacterial viability and culture medium composition. This is the first study carried out to study OTA removal dynamics by living and heat-inactivated cells of O. oeni. The results aim that this bacterium may be a very useful tool to control OTA in food and beverages. (C) 2009 Els…
Malolactic fermentation in white wines
2022
Abstract Malolactic fermentation (MLF) is an important process in wine production and involves the bioconversion of malic acid into lactic acid and CO2. However, many other biochemical reactions occur simultaneously, and several other grape must and wine compounds are also modified besides malic acid. Some can improve quality, while others may be detrimental to sensory quality or health. Among them, there are the synthesis of carbonyl compounds, esters, monoterpenes, volatile phenols, acetamide or mousy odor, methanethiol, dimethyl disulfide, methionol, 3-(methylsulfanyl) propionic acid, citrulline, or biogenic amines. The role of MLF in winemaking is triple: reducing the acidity of the win…
Dynamics of Microbial Populations during Fermentation of Wines from the Utiel-Requena Region of Spain
1989
The dynamics of fungi, yeasts, and lactic acid bacteria during fermentation of four musts were studied. Fungi disappeared quickly in the fermenting must. The lactic acid bacteria population diminished during alcoholic fermentation, then they increased and performed malolactic fermentation. Yeasts grew quickly, reaching maximum populations at different times depending on the vinification treatment.
Improvement of volatile composition of wines by controlled addition of malolactic bacteria
1999
The effect of malolactic fermentation (MLF) on the volatile composition of red wines was studied by inoculation with selected lactic acid bacteria. Four wines were inoculated with different Oenococcus oeni (syn. Leuconostoc oenos) strains, the major malolactic species found in wines, and one was inoculated with a Lactobacillus sp. strain. A non inoculated wine was also analyzed to act as a control. Malolactic fermentation and evolution of non volatile compounds were followed by HPLC and after the depletion of the malic acid present in wine the volatile compounds were extracted and analyzed by gas chromatography with flame ionization and mass spectrometry. Wines which had undergone the MLF s…
Direct and Rapid Detection and Quantification of Oenococcus oeni Cells in Wine by Cells-LAMP and Cells-qLAMP
2018
Fast detection and enumeration of Oenococcus oeni in winemaking are necessary to determine whether malolactic fermentation (MLF) is likely to be performed or not and to decide if the use of a commercial starter is needed. In other wines, however, performing MLF can be detrimental for wine and should be avoided. The traditional identification and quantification of this bacteria using culture-dependent techniques in wine-related matrices require up to 14 days to yield results, which can be a very long time to perform possible enological operations. Loop-mediated isothermal amplification (LAMP) is a novel culture-independent technique that amplifies nucleic acid sequences under isothermal cond…
Recombinant laccase from Pediococcus acidilactici CECT 5930 with ability to degrade tyramine
2017
Biogenic amines degradation by bacterial laccases is little known, so we have cloned and heterologously expressed, in E. coli, a new laccase from Pediococcus acidilactici CECT 5930 (Lpa5930), a lactic acid bacterium commonly found in foods able to degrade tyramine. The recombinant enzyme has been characterized by physical and biochemical assays. Here we report the optimization of expression and purification procedures of this laccase. DNA encoding sequence of laccase from P. acidilactici was amplified by PCR and cloned into the expression plasmid pET28a for induction by isopropyl-β-D-thiogalactoipyranoside. Protein expression was performed in E. coli BL21(DE3) harboring pGro7 plasmid expres…
Lactobacillus bobalius sp. nov., a lactic acid bacterium isolated from Spanish Bobal grape must
2008
A Lactobacillus strain, designated 203(T), previously isolated from Bobal grape must was characterized phylogenetically, genotypically and phenotypically in order to establish whether it represents a novel species. On the basis of the 16S rRNA gene sequence, strain 203(T) was shown to belong to the genus Lactobacillus, falling within the Lactobacillus alimentarius-Lactobacillus farciminis group and being closely related to the type strains of L. alimentarius, Lactobacillus kimchii and Lactobacillus paralimentarius. DNA-DNA hybridization results confirmed the separate status of strain 203(T) at the species level. To establish the similarities and differences between 203(T) and the three afor…
Histamine, histidine, and growth-phase mediated regulation of the histidine decarboxylase gene in lactic acid bacteria isolated from wine
2006
Fermented foods are frequently contaminated by histamine that is generated by microorganisms with histidine decarboxylase activity. The ingestion of large amounts of histamine can cause serious toxicological problems in humans. A study of the effects of histamine, histidine, and growth phase on histamine production by lactic acid bacteria isolated from wine is reported here. With northern blots and specific activity analysis, we observed that histidine induces the expression of the histidine decarboxylase gene (hdc) and that histamine causes a decrease in the expression of this gene. The expression of hdc is also mediated by the bacterial growth phase. Histidine and histamine do not affect …
Exploring the biodiversity of two groups of Oenococcus oeni isolated from grape musts and wines: Are they equally diverse?
2016
One hundred and four Oenococcus oeni isolates were characterised by the carbohydrate fermentation (CH) profile and DNA fingerprinting. Forty-four isolates came from grape must, and 60 from wines sampled at the end of alcoholic fermentation or during malolactic fermentation. The grape must isolates fermented more CH than the wine isolates. In genotypical terms, no clear boundary between grape must and wine isolates was found. Diversities were deduced by considering the isolates of grape must and of wine separately and jointly. By considering only CH fermentation abilities, the group of grape must isolates gave higher diversity index (DICH) values than those isolated from wine; i.e., these is…
Cells-qPCR as a direct quantitative PCR method to avoid microbial DNA extractions in grape musts and wines.
2017
A novel quantitative PCR assay called Cells-qPCR has been developed for the rapid detection and quantification of yeasts, lactic acid bacteria (LAB) and acetic acid bacteria (AAB) directly from grape must and wine that does not require DNA extraction. The assay was tested on Brettanomyces bruxellensis, Saccharomyces cerevisiae, Lactobacillus plantarum, Oenococcus oeni, Acetobacter aceti and Gluconobacter oxydans in culture media, and in white and red grape musts and wines. Standard curves were constructed from DNA and cells for the six target species in all the matrices. Good efficiencies were obtained for both when comparing DNA and cells standard curves. No reaction inhibition was observe…
Lowering histamine formation in a red Ribera del Duero wine (Spain) by using an indigenous O. oeni strain as a malolactic starter
2016
This study demonstrates for the first time that a non-commercial selected autochthonous O. oeni strain has been used to conduct malolactic fermentation (MLF) while lowering histamine formation in the same winery. Lactic acid bacteria (LAB) were isolated from 13 vats before and after spontaneous MLF at the Pago de Carraovejas winery from the Ribera del Duero region (Spain). Only O. oeni were present, typed and characterized, and both histamine producer and non-producers existed. From the non-producers, one strain was selected to become a starter according to its genetic profile, prevalence in the different wines in the winery, resistance to alcoholic degree, resistance to high polyphenolic c…
Lactobacillus vini sp. nov., a wine lactic acid bacterium homofermentative for pentoses.
2006
Six strains with more than 99·5 % 16S rRNA gene sequence similarity, identical internal spacer region profiles and restriction analysis of the amplified 16S rRNA gene patterns were isolated from fermenting grape musts during independent studies carried out in France and Spain many years apart. Strains are Gram-positive, motile, facultatively anaerobic rods that do not exhibit catalase activity and have the ability to utilize pentose sugars (ribose and/or l-arabinose), although they are homofermentative bacteria. Strains ferment pentoses exclusively yielding lactic acid as the end product. A broad set of molecular techniques has been applied to characterize these strains and the results show…
Structural analysis and biochemical properties of laccase enzymes from two Pediococcus species
2021
Summary Prokaryotic laccases are emergent biocatalysts. However, they have not been broadly found and characterized in bacterial organisms, especially in lactic acid bacteria. Recently, a prokaryotic laccase from the lactic acid bacterium Pediococcus acidilactici 5930, which can degrade biogenic amines, was discovered. Thus, our study aimed to shed light on laccases from lactic acid bacteria focusing on two Pediococcus laccases, P. acidilactici 5930 and Pediococcus pentosaceus 4816, which have provided valuable information on their biochemical activities on redox mediators and biogenic amines. Both laccases are able to oxidize canonical substrates as ABTS, ferrocyanide and 2,6‐DMP, and non‐…
A selective medium for the isolation of malolactic mutants of Leuconostoc oenos
1994
We have developed a selective medium for the isolation of Leuconostoc oenos mutants defective in malolactic fermentation. Forty per cent of colonies isolated directly on selective plates after UV mutagenesis had lost their ability to degrade malate. None of the tested mutants showed any detectable malolactic activity and all lacked a protein band corresponding in size to that of the malolactic enzyme. The availability of such mutants provides a valuable tool both for physiological and genetic research on malolactic fermentation.
Development of specific fluorescent oligonucleotide probes for in situ identification of wine lactic acid bacteria.
2003
A rapid method for the identification of lactic acid bacteria (LAB) from wine has been developed. This method is based on fluorescence in situ hybridisation (FISH), using fluorescent oligonucleotide probes, homologous to 16S rDNA of those species of LAB commonly found in wines. The protocol for the specific detection of these bacteria was established through the hybridisation of 36 reference strains. The specificity of the probes was evaluated by using pure cultures. Probes were used to identify species in different wines, making it evident that direct identification and quantification from natural samples without culturing is also possible. The results show that FISH is a promising techniq…
Technological properties of Lactobacillus plantarum strains isolated from grape must fermentation
2016
Malolactic fermentation (MLF) is a secondary fermentation in wine that usually takes place during or at the end of alcoholic fermentation. Lactobacillus plantarum is able to conduct MLF (particularly under high pH conditions and in co-inoculation with yeasts) and some strains are commercially used as MLF starter cultures. Recent evidences suggest a further use of selected L. plantarum strains for the pre-alcoholic acidification of grape must. In this study, we have carried out an integrated (molecular, technological, and biotechnological) characterization of L. plantarum strains isolated from Apulian wines in order to combine the two protechnological features (MLF performances and must acid…
Science Advances
2019
River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth’s biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constrai…