Lactobacillus Hilgardii Research Articles

Multicopper Oxidase from Lactobacillus hilgardii: Mechanism of Degradation of Tyramine and Phenylethylamine in Fermented Food.

Elevated levels of biogenic amines (BAs) in fermented food can have negative effects on both the flavor and health. Mining enzymes that degrade BAs is an effective strategy for controlling their content. The study screened a strain of Lactobacillus hilgardii 1614 from fermented food system that can degrade BAs. The multiple copper oxidase genes LHMCO1614 were successfully mined after the whole genome protein sequences of homologous strains were clustered and followed by homology modeling. The enzyme molecules can interact with BAs to stabilize composite structures for catalytic degradation, as shown by molecular docking results. Ingeniously, the kinetic data showed that purified LHMCO1614 was less sensitive to the substrate inhibition of tyramine and phenylethylamine. The degradation rates of tyramine and phenylethylamine in huangjiu (18% vol) after adding LHMCO1614 were 41.35 and 40.21%, respectively. Furthermore, LHMCO1614 demonstrated universality in degrading tyramine and phenylethylamine present in other fermented foods as well. HS-SPME-GC-MS analysis revealed that, except for aldehydes, the addition of enzyme treatment did not significantly alter the levels of major flavor compounds in enzymatically treated fermented foods (p > 0.05). This study presents an enzymatic approach for regulating tyramine and phenylethylamine levels in fermented foods with potential applications both targeted and universal.

Licuri Kernel (Syagrus coronata (Martius) Beccari): A Promising Matrix for the Development of Fermented Plant-Based Kefir Beverages.

New licuri-based kefir beverages were obtained using water kefir grains as fermentation inoculum (1, 2.5, and 5%) under different fermentation times (24 and 48 h). Metagenomic sequencing of the kefir grains adapted to the aqueous licuri extract revealed Lactobacillus hilgardii and Brettanomyces bruxellensis to be predominant in this inoculum. The excellent adaptation of the kefir grains to the licuri extract raised the possibility of prebiotic action of these almonds. The beverages showed acidity values between 0.33 ± 0.00 and 0.88 ± 0.00 mg lactic acid/100 mL and pH between 3.52 ± 0.01 and 4.29 ± 0.04. The viability of lactic acid bacteria in the fermented beverages was equal to or greater than 108 CFU/mL, while yeasts were between 104 and 105 CFU/mL. There were significant differences (p < 0.05) in the proximate composition of the formulations, especially in the protein (1.37 ± 0.33-2.16 ± 0.84) and carbohydrate (5.86 ± 0.19-11.51 ± 1.26) contents. In addition, all the samples showed good stability in terms of acidity, pH, and viability for LAB and yeasts during 28 days of storage (4 °C). Overall, the beverages showed a dominant yellow-green color, non-Newtonian pseudoplastic behavior, and high mean scores in the sensory evaluation. This study provided evidence of the emerging potential of licuri in the plant-based beverage industry.

Optimization of fermentation conditions for the production of γ-aminobutyric acid by Lactobacillus hilgardii GZ2 from traditional Chinese fermented beverage system.

γ-Aminobutyric acid (GABA) is a crucial neurotransmitter with wide application prospects. In this study, we focused on a GABA-producing strain from a traditional Chinese fermented beverage system. Among the six isolates, Lactobacillus hilgardii GZ2 exhibited the greatest ability to produce GABA in the traditional Chinese fermented beverage system. To increase GABA production, we optimized carbon sources, nitrogen sources, temperature, pH, and monosodium glutamate and glucose concentrations and conducted fed-batch fermentation. The best carbon and nitrogen sources for GABA production and cell growth were glucose, yeast extract and tryptone. Gradual increases in GABA were observed as the glucose and monosodium glutamate concentrations increased from 10g/L to 50g/L. During fed-batch fermentation, lactic acid was used to maintain the pH at 5.56, and after feeding with 0.03g/mL glucose and 0.4g/mL sodium glutamate for 72h, the GABA yield reached 239g/L. This novel high-GABA-producing strain holds great potential for the industrial production of GABA, as well as the development of health-promoting functional foods and medical fields.

The gain effect of microbial consortia induced by adaptive domestication for efficient conversion of Chinese cabbage waste by anaerobic fermentation

The resource-based treatment of Chinese cabbage waste by anaerobic fermentation can effectively mitigate air, soil, and groundwater pollution. However, the compatibility between fermentative microorganisms and the environment might be a crucial limiting factor for the resource recycling of Chinese cabbage waste. Therefore, the gain effect of microbial consortia (JMRS, JMRST, JMRSZ, JCCW, JCCWT and JCCWZ) induced by adaptive domestication for efficient conversion of Chinese cabbage waste by anaerobic fermentation were explored in this study. A total of 42 single subsamples with same weights were randomly divided into seven treatments: sterile deionized water (Control); anaerobic fermentation inoculated with JMRS (MRS); anaerobic fermentation inoculated with JMRST (MRST); anaerobic fermentation inoculated with JMRSZ (MRSZ); anaerobic fermentation inoculated with JCCW (CCW); anaerobic fermentation inoculated with JCCWT (CCWT); anaerobic fermentation inoculated with JCCWZ (CCWZ) and samples were taken on days 30 and 60 after anaerobic fermentation. The results exhibited that all the treatments contributed to high levels of lactic acid (178.77–201.79 g/kg dry matter) and low levels of ammonia-N (12.99–21.03 g/kg total nitrogen). Meanwhile, MRSZ enhanced (p < 0.05) acetic acid levels (1.53 g/kg dry matter) and resulted in the lowest yeast counts. Microbiologically, the addition of microbial consortia decreased the linear discriminant analysis (LDA) scores of Massilia and Stenotrophomonas maltophilia. Moreover, MRSZ enriched (p < 0.05) Lactobacillus hilgardii, and decreased (p < 0.05) the abundance of bacteria containing mobile elements and potentially pathogenic bacteria. In conclusion, JMRSZ improved the efficient conversion of Chinese cabbage waste for resource utilization.

Silkworm Pupae Coupled with Glucose Control pH Mediates GABA Hyperproduction by Lactobacillus hilgardii

γ-Aminobutyric acid (GABA) is a ubiquitous nonprotein amino acid that has multiple physiological functions and has received significant attention in the pharmaceutical and food industries. Although there are many GABA-producing bacteria, the high cost of strain cultivation limits its food additive and pharmaceutical raw material application. In our study, Lactobacillus hilgardii GZ2, a novel GABA-producing strain, was investigated. We attempted to replace nitrogen sources with silkworm pupae, the waste resource of the silk reeling industry, in GYP complex medium. The GABA titer reached 33.2 g/L by using 10 g/L silkworm pupae meal instead of tryptone. Meanwhile, the pH of fermentation was automatically controlled by adjusting the addition of glucose and monosodium glutamate. Finally, the highest GABA yield and productivity were 229.3 g/L and 3.2 g/L/h in L. hilgardii when silkworm pupae meal was replaced with tryptone combined with glucose and monosodium glutamate feeding. By utilizing the waste resource to reduce the cost of the nitrogen source and automatically controlling the pH in L. hilgardii, a hyper titer and productivity of GABA was generated for applications in the food and pharmaceutical industries.

Effects of citric acid and heterofermentative inoculants on anaerobic co-fermentation of Chinese cabbage waste and wheat bran

The effects of Lactobacillus buchneri, Lactobacillus hilgardii and citric acid on organic acid production, substrate consumption, protein degradation and microbial community were investigated in this study. The results indicated that combined inoculants induced a significant increase in levels of lactic acid (43 g/kg dry matter), acetic acid (14 g/kg dry matter), butyric acid (5 g/kg dry matter), total organic acid (60 g/kg dry matter) and ammonia nitrogen (20 g/kg total nitrogen). Furthermore, citric acid addition into the combined inoculants caused a significant increase in levels of acetic acid (12 g/kg dry matter), water-soluble carbohydrate (12 g/kg dry matter) and a reduction in ammonia nitrogen formation (22 g/kg total nitrogen). Microbiologically, combining inoculants and citric acid enriched Lactobacillus buchneri and Lactobacillus hilgardii and upregulated the functional pathways related to acid production and resistance. Collectively, combining citric acid and heterofermentative inoculants was beneficial to recycle Chinese cabbage waste in producing organic acids.

Metabolic characteristics of lactic acid bacteria and interaction with yeast isolated from light-flavor Baijiu fermentation

During spontaneous fermentation of light-flavor Baijiu, the microbial diversity decreased gradually. Lactic acid bacteria (LAB) and yeast predominated at the end of fermentation and showed a strong positive correlation with esters in Baijiu. Exploring the metabolic characteristics of LAB and interactions with yeast are important for revealing the mechanism of Baijiu fermentation. The carbon source utilization heatmap showed that Lactobacillus acetotolerans, Lactobacillus brevis, and Lactobacillus hilgardii could utilize various organic acids. Lactobacillus plantarum could utilize a variety of amino acids. The utilization efficiency of different substrates was supposed to be an important factor for different LAB species dynamics during fermentation. The effects of pH, temperature and ethanol on the esterase activity of LAB were further analyzed. The results showed that pH was the most significant factor on esterase activity, and all the strains showed the highest activity at pH 7.0. Principal component analysis indicated that co-culture of LAB and Saccharomyces cerevisiae could promote the formation of esters, and the co-culture of Lactobacillus acetotolerans or Leuconostoc mesenteroides with Pichia anomala could promote the production of esters and alcohols. LAB showed a weak inhibitory effect on the growth of yeast, whereas the growth of LAB was significantly inhibited by yeast in the co-culture system. The results of this work will broaden our knowledge regarding the esterase activity, carbon source utilization efficiency of LAB and interactions with predominant yeast, which will provide a theoretical basis for the dynamics of different LAB species and their effects on the flavor of Baijiu.

Isolation and Characterization of High-Ethanol-Tolerance Lactic Acid Bacteria from Australian Wine.

Lactic acid bacteria are very important in winemaking. In this study, 108 lactic acid bacteria isolates were obtained from high-ethanol-content (~17% (v/v)) Grenache wines during uninoculated malolactic fermentation (MLF). The 16S rRNA and species-specific PCR showed that 104 of these were Oenococcus oeni, three were Lactobacillus hilgardii, and one was Staphylococcus pasteuri. AFLP of HindIII and MseI digests of the genomic DNA of the O. oeni strains was developed for the first time to discriminate the strains. The results showed that the method was a suitable technique for discriminating the O. oeni strains. Based on the cluster analysis, nine O. oeni strains were chosen for inclusion in an ethanol tolerance assay involving monitoring of optical density (ABS600nm) and viable plating. Several O. oeni strains (G63, G46, G71, G39) survived and grew well in MRS-AJ with 17% (v/v) ethanol, while the commercial O. oeni reference strain did not. Strain G63 could also survive and grow for 168 h after inoculation in MRS-AJ medium with 19% (v/v) ethanol. These results suggest that O. oeni G63, G46, G71, and G39 could potentially be used as MLF starters for high-ethanol-content wines. All three L. hilgardii strains could survive and grow in MRS-AJ with 19% (v/v) ethanol, perhaps also indicating their suitability as next-generation MLF starter cultures.

Metagenomic and phytochemical analyses of kefir water and its subchronic toxicity study in BALB/c mice

BackgroundIn recent years, researchers are interested in the discovery of active compounds from traditional remedies and natural sources, as they reveal higher therapeutic efficacies and improved toxicological profiles. Among the various traditional treatments that have been widely studied and explored for their potential therapeutic benefits, kefir, a fermented beverage, demonstrates a broad spectrum of pharmacological properties, including antioxidant, anti-inflammation, and healing activities. These health-promoting properties of kefir vary among the kefir cultures found at the different part of the world as different media and culture conditions are used for kefir maintenance and fermentation.MethodsThis study investigated the microbial composition and readily found bioactive compounds in water kefir fermented in Malaysia using 16S rRNA microbiome and UHPLC sequencing approaches. The toxicity effects of the kefir water administration in BALB/c mice were analysed based on the mice survival, body weight index, biochemistry profile, and histopathological changes. The antioxidant activities were evaluated using SOD, FRAP, and NO assays.ResultsThe 16S rRNA amplicon sequencing revealed the most abundant species found in the water kefir was Lactobacillus hilgardii followed by Lactobacillus harbinensis, Acetobacter lovaniensis, Lactobacillus satsumensis, Acetobacter tropicalis, Lactobacillus zeae, and Oenococcus oeni. The UHPLC screening showed flavonoid and phenolic acid derivatives as the most important bioactive compounds present in kefir water which has been responsible for its antioxidant activities. Subchronic toxicity study showed no toxicological signs, behavioural changes, or adverse effects by administrating 10 mL/kg/day and 2.5 mL/kg/day kefir water to the mice. Antioxidants assays demonstrated enhanced SOD and FRAP activities and reduced NO level, especially in the brain and kidney samples.ConclusionsThis study will help to intensify the knowledge on the water kefir microbial composition, available phytochemicals and its toxicological and antioxidant effects on BALB/c mice since there are very limited studies on the water kefir grain fermented in Malaysia.

Genome and Pangenome Analysis of Lactobacillus hilgardii FLUB-A New Strain Isolated from Mead.

The production of mead holds great value for the Polish liquor industry, which is why the bacterium that spoils mead has become an object of concern and scientific interest. This article describes, for the first time, Lactobacillus hilgardii FLUB newly isolated from mead, as a mead spoilage bacteria. Whole genome sequencing of L. hilgardii FLUB revealed a 3 Mbp chromosome and five plasmids, which is the largest reported genome of this species. An extensive phylogenetic analysis and digital DNA-DNA hybridization confirmed the membership of the strain in the L. hilgardii species. The genome of L. hilgardii FLUB encodes 3043 genes, 2871 of which are protein coding sequences, 79 code for RNA, and 93 are pseudogenes. L. hilgardii FLUB possesses three clustered regularly interspaced short palindromic repeats (CRISPR), eight genomic islands (44,155 bp to 6345 bp), and three (two intact and one incomplete) prophage regions. For the first time, the characteristics of the genome of this species were described and a pangenomic analysis was performed. The concept of the pangenome was used not only to establish the genetic repertoire of this species, but primarily to highlight the unique characteristics of L. hilgardii FLUB. The core of the genome of L. hilgardii is centered around genes related to the storage and processing of genetic information, as well as to carbohydrate and amino acid metabolism. Strains with such a genetic constitution can effectively adapt to environmental changes. L. hilgardii FLUB is distinguished by an extensive cluster of metabolic genes, arsenic detoxification genes, and unique surface layer proteins. Variants of MRS broth with ethanol (10–20%), glucose (2–25%), and fructose (2–24%) were prepared to test the strain’s growth preferences using Bioscreen C and the PYTHON script. L. hilgardii FLUB was found to be more resistant than a reference strain to high concentrations of alcohol (18%) and sugars (25%). It exhibited greater preference for fructose than glucose, which suggests it has a fructophilic nature. Comparative genomic analysis supported by experimental research imitating the conditions of alcoholic beverages confirmed the niche specialization of L. hilgardii FLUB to the mead environment.

The Type and Concentration of Inoculum and Substrate as Well as the Presence of Oxygen Impact the Water Kefir Fermentation Process.

Eleven series of water kefir fermentation processes differing in the presence of oxygen and the type and concentration of inoculum and substrate, were followed as a function of time to quantify the impact of these parameters on the kinetics of this process via a modeling approach. Increasing concentrations of the water kefir grain inoculum increased the water kefir fermentation rate, so that the metabolic activity during water kefir fermentation was mainly associated with the grains. Water kefir liquor could also be used as an alternative means of inoculation, but the resulting fermentation process progressed slower than the one inoculated with water kefir grains, and the production of water kefir grain mass was absent. Substitution of sucrose with glucose and/or fructose reduced the water kefir grain growth, whereby glucose was fermented faster than fructose. Lacticaseibacillus paracasei (formerly known as Lactobacillus paracasei), Lentilactobacillus hilgardii (formerly known as Lactobacillus hilgardii), Liquorilactobacillus nagelii (formerly known as Lactobacillus nagelii), Saccharomyces cerevisiae, and Dekkera bruxellensis were the main microorganisms present. Acetic acid bacteria were present in low abundances under anaerobic conditions and only proliferated under aerobic conditions. Visualization of the water kefir grains through scanning electron microscopy revealed that the majority of the microorganisms was attached onto their surface. Lactic acid bacteria and yeasts were predominantly associated with the grains, whereas acetic acid bacteria were predominantly associated with the liquor.

Microbiota succession during aerobic stability of maize silage inoculated with Lentilactobacillus buchneri NCIMB 40788 and Lentilactobacillus hilgardii CNCM-I-4785.

Aerobic deterioration of silage following feeding out is responsible for the deterioration of its quality. Inoculation of silage with lactic acid bacteria is one strategy to limit these effects. A trial was performed using whole‐plant corn ensiled in bag silo, and forage was inoculated with Lentilactobacillus buchneri NCIMB 40788 (Lactobacillus buchneri) and Lentilactobacillus hilgardii CNCM‐I‐4785 (Lactobacillus hilgardii) or not (Control silage). After 159 days of fermentation, the silos were opened and the silage was sampled at 24‐h intervals during a 10‐day aerobic stability assay to measure pH, the fermentation profile, mycotoxins, and microbial and fungal populations. In inoculated silage, lactic acid concentrations and pH remained stable during the aerobic phase and higher microorganism alpha‐diversity was observed. Treated silage was characterized by a high abundance of Saccharomycetes and maintenance of Lactobacillus throughout the aerobic stability assay. The high aerobic stability of the inoculated silage contrasted with the decrease in lactic acid contents and the increase in pH observed in the Control silage, concomitantly with an increase in lactate‐assimilating yeast (Pichia and Issatchenkia), and in Acetobacter and Paenibacillus OTUs. Remarkably, Penicillium and roquefortine C were detected in this silage by day 8 following exposure to air. Our study highlighted the fact that the use of L. buchneri with L. hilgardii modified the consequences of exposure to air by maintaining higher microbial diversity, avoiding the dominance of a few bacteria, and preventing fungi from having a detrimental effect on silage quality.

Temperature during conservation in laboratory silos affects fermentation profile and aerobic stability of corn silage treated with Lactobacillus buchneri, Lactobacillus hilgardii, and their combination

The environment temperature and its effect on the temperature of silage is very important for the fermentation and subsequent quality of a silage. Obligate heterofermentative lactic acid bacteria (LAB) inocula, because of their ability to inhibit yeasts, have been developed to prevent the aerobic deterioration of silages. The temperature during silage conservation may also play an important role in the fermentation profile of silages. This study has evaluated the effect of temperature, during the conservation of whole crop corn silage, untreated or treated with different LAB inocula, on the fermentation profile and on the aerobic stability of the silage. Corn was harvested at 42% dry matter and either not treated (control) or treated with Lactobacillus buchneri NCIMB 40788 (LB) at 300,000 cfu/g fresh matter (FM); Lactobacillus hilgardii CNCM I-4785 at 150,000 cfu/g FM (LH150); L. hilgardii CNCM I-4785 at 300,000 cfu/g FM (LH300); or LB+LH at 150,000 cfu/g FM each. In an attempt to experimentally simulate temperature fluctuations in the mass or at the periphery of a silage bunker, corn was conserved in laboratory silos at a constant temperature (20 ± 1°C; MASS) or at lower and variable outdoor temperatures (PERIPH; ranging from 0.5 to 19°C), and the silos were opened after 15, 30, and 100 d of conservation. Lactic acid, acetic acid, and ethanol contents increased in all the silages over the conservation period. The lactic acid content was higher (+10%) in the silages kept at a constant temperature than those conserved at the lower and variable outdoor temperatures. The acetic acid was higher in the treated silages than in the control ones conserved at a constant temperature for 100 d. Moreover, 1,2-propanediol was only detected in the treated silages after at least 30 d at a constant temperature, whereas only traces were detected in the LB+LH treatment for the other temperature conditions. The yeast count decreased during conservation at a slower rate in PERIPH than in MASS and on average reached 2.96 and 4.71 log cfu/g for MASS and PERIPH, respectively, after 100 d of conservation. The highest aerobic stability values were observed for LH300 (191 h) in the MASS silage after 100 d of conservation, whereas the highest aerobic stability was observed in LB+LH (150 h) in the PERIPH silages. After 7 d of air exposure, a pH higher than 4.5 and a higher yeast than 8.0 log cfu/g were detected in all the silages opened after 15 and 30 d of conservation. A pH value close to that of silo opening was detected in the LB, LH150, and LH300 silages conserved under MASS conditions after 100 d, whereas LB+LH was the most effective under PERIPH conditions. The temperature and its fluctuation during conservation of silage in laboratory silos influenced the fermentation, which in turn had an effect on the quality of silage and on the extent of the effect of LAB inocula.

Effects of Lactobacillus hilgardii 4785 and Lactobacillus buchneri 40788 on the bacterial community, fermentation and aerobic stability of high-moisture corn silage.

To evaluate the capacity of Lactobacillus hilgardii and Lactobacillus buchneri on modifying the bacterial community and improving fermentation and aerobic stability of high-moisture corn (HMC). High-moisture corn was untreated (CTR), treated with L. hilgardii (LH) or L. buchneri (LB) at 600000CFU per gram fresh weight, or with L. hilgardii and L. buchneri at 300000CFU per gram fresh weight each (LHLB), and stored for 10, 30 or 92days. Compared to CTR, inoculated silages had higher Lactobacillaceae relative abundance, lower yeasts numbers and higher aerobic stability. Treatment with LHLB resulted in a higher acetic acid concentration than LH and higher 1,2 propanediol concentration than LB, such differences were numerically greater at 10 and 30days but statistically greater at 92days. At 10days, all inoculated silages were more stable than CTR, but LHLB was even more stable than LB or LH. The combination of L. hilgardii and L. buchneri had a synergistic effect on yeast inhibition, leading to greater improvements in aerobic stability as early as 10days after ensiling. Lactobacillus hilgardii, especially in combination with L. buchneri, can improve the aerobic stability of HMC after a very short period of ensiling.

Development and characterization of a pure stilbene extract from grapevine shoots for use as a preservative in wine

Grapevine shoots, known to be a source of bioactive stilbenes, are considered one of the most important and abundant waste products from the vineyard. The objective of this study was to obtain a pure stilbene extract from grapevine shoots and test its properties, mainly antimicrobial ones, as a preservative in wine. A new extract with a purity of 99% in stilbenes was obtained by centrifugal partition chromatography. The extract was characterized by HPLC-MS, the main compounds being E-ε-viniferin (70%) and E-resveratrol (18%). The stability conditions for the extract solution were low temperature (4 °C) and darkness for a maximum of 21 days. Data regarding to the stability of E-ϵ-viniferin, ω-viniferin and r-viniferin are reported first.The antimicrobial activity of the extract was higher against yeast (Brettanomyces bruxellensis, Zygosaccharomyces bailli, Haseniaspora uvarum, Candida zemplinina) than against bacteria (Lactobacillus hilgardii, Oenococcus oeni, Pediococcus pentasaceus). The best antimicrobial activity was found on Brettanomyces bruxellensis and Zygossaccharomyces bailli. The aromatic characterization of the extract allows us to establish that it does not affect the sensory properties of wine, and thus wine quality is not compromised with the addition of the extract. All of the above allow us to propose ST99 as a promising alternative to SO2 in wines, including rose and white wines.

Complete Genome Sequence of Lactobacillus hilgardii LMG 7934, Carrying the Gene Encoding for the Novel PII-Like Protein PotN.

Lactic acid bacteria are widespread in various ecological niches with the excess of nutrients and have reduced capabilities to adapt to starvation. Among more than 280 Lactobacillus species known to the date, only five, including Lactobacillus hilgardii, carry in their genome the gene encoding for PII-like protein, one of the central regulators of cellular metabolism generally responding to energy- and carbon-nitrogen status in many free-living Bacteria, Archaea and in plant chloroplasts. In contrast to the classical PII encoding genes, in L.hilgardii genome the gene for PII homologue is located within the potABCD operon, encoding the ABC transporter for polyamines. Based on the unique genetic context and low sequence identity with genes of any other so-far characterized PII subfamilies, we termed this gene potN (Pot-protein, Nucleotide-binding). The second specific feature of L.hilgardii genome is that many genes encoding the proteins with similar function are present in two copies, while with low mutual identity. Thus, L.hilgardii LMG 7934 genome carries two genes of glutamine synthetase with 55% identity. One gene is located within classical glnRA operon with the gene of GlnR-like transcriptional regulator, while the second is monocistronic. Together with the relative large genome of L.hilgardii as compared to other Lactobacilli (2.771.862bp vs ~ 2.2 Mbp in median), these data suggest significant re-arrangements of the genome and a wider range of adaptive capabilities of L.hilgardii in comparison to other bacteria of the genus Lactobacillus.

Thermosonication as an alternative method for processing, extending the shelf life, and conserving the quality of pulque: A non-dairy Mexican fermented beverage

The aim of this study was to evaluate thermosonication as an alternative method for the pasteurization of pulque in order to improve its shelf life and retain its quality parameters.Thermosonication was carried out at 50 °C using amplitudes of 75% (for 6 and for 9 min), 85% (for 4 and for 6 min), and 95% (for 3 and for 5 min). These were the optimal conditions found for processing pulque by thermosonication. Physicochemical (acidity, color, alcohol content, and sensory analysis) and microbiological (lactic acid bacteria and yeasts) parameters were determined during 30 days for storage at 4 ± 1 °C. Conventional pasteurization (63 °C, 30 min) and raw pulque were used as controls. According to the results, the shelf life of pulque was extended up to 24 days storage at 4 °C. After this time, the quality of beverage decreased, due that the microbial load increases. Thermosonication treatments at 75% and 85% showed a higher content of LAB (6.58–6.77 log CFU/mL) and yeasts (7.08–7.27 log CFU/mL) than conventional pasteurization (3.64 log CFU/mL of LAB and 3.97 log CFU/mL of yeasts) at 24 days of storage. Raw pulque demonstrated up to 7.77 log CFU/mL of yeasts and 7.51 log CFU/mL of LAB. Pulque processed by thermosonication exhibited greater lightness, sensory acceptance, a maximal acidity of 0.83 g/lactic acid, and an alcohol content of 4.48–4.95% v/v. The thermosonication process preserves sensory and physicochemical properties better than conventional pasteurization. Lactic acid bacteria such as Lactobacillus kefiri, Lactobacillus acidophilus, and Lactobacillus hilgardii and yeasts such as Saccharomyces cereviasiae were identified in thermosonicated pulque.

Effects of Lactobacillus hilgardii 60TS-2, with or without homofermentative Lactobacillus plantarum B90, on the aerobic stability, fermentation quality and microbial community dynamics in sugarcane top silage

This study investigated the effects of Lactobacillus hilgardii (LH), alone or in combination with Lactobacillus plantarum (LP), on the aerobic stability, fermentation quality and dynamics of the bacterial and fungal communities of sugarcane top silage. Results demonstrated that LH and LHLP (LH combined with LP) improved the aerobic stability of sugarcane top silages. As the exposure time increased, the pH values and the contents of lactic acid, acetic acid, as well as propionic acid remained stable in silage treated with LH and LHLP. The abundance of L. hilgardii was enriched and the undesirable microorganisms, such as Acetobacter pasteurianus, Paenibacillus amylolyticus and yeasts like Kazachstania humilis, were suppressed in silages treated with LH and LHLP. In conclusion, LH-treated silage, whether with LP or not, positively impacted the fungal and bacterial microbes. This improved the quality of fermentation, the aerobic stability, and reduced aerobic spoilage in sugarcane top silage.

Wine Lactic Acid Bacteria with Antimicrobial Activity as Potential Biocontrol Agents against Fusarium oxysporum f. sp. lycopersici

Lactic acid bacteria isolated from wine fermentations, particularly from the malolactic fermentation, and belonging to Lactobacillus plantarum, Lactobacillus hilgardii, Lactobacillus paracasei and Lactococcus lactis species were tested for their effectiveness in inhibiting the development of different microorganisms. The different strains showed, to varying degrees, an antagonistic effect against bacteria of the genera Bacillus and Staphylococcus. The specificity of the species L. hilgardii that inhibits only strains of the genus Bacillus is remarkable, on the other hand, L. plantarum was more effective against the strains of the genus Staphylococcus. The greatest effectiveness, considering both the degree of inhibition and the number of inhibited species, was presented by strains of L. lactis and L. paracasei. Seven strains belonging to the species that showed a more broad-spectrum activity, L. paracasei and L. plantarum, were also tested for their ability to inhibit the growth of fungi. All of them showed, in different degree (55–76%), activity against Fusarium oxysporum. Finally, the ability of the L. paracasei LPAUV12 and L. plantarum LPLUV10 strains was evaluated to protect Lycopersicon esculentum plants against the fungus F. oxysporum and promote its growth. Strain LPLUV10, showed capacity to significantly inhibit the harmful effect of F. oxysporum in tomato plants as well as to significantly stimulate their growth.

The Buffer Capacity and Calcium Concentration of Water Influence the Microbial Species Diversity, Grain Growth, and Metabolite Production During Water Kefir Fermentation.

Eight water kefir fermentation series differing in buffer capacity and calcium concentration of the water used for fermentation were studied during eight backslopping steps. High buffer capacities resulted in high pH values and high calcium concentrations resulted in low pH values at the end of each backslopping step. When the water buffer capacity and/or calcium concentration were below certain minima, the water kefir grain growth decreased gradually over multiple backsloppings. High water buffer capacities resulted in high concentrations of residual total carbohydrate concentrations and low metabolite concentrations. Further, high water buffer capacities resulted in high ratios of lactic acid bacteria to yeasts, which was reflected in high molar ratios of the concentrations of lactic acid to ethanol and acetic acid to ethanol. The most prevalent microorganisms of the water kefir grain inoculum and grains of all fermentation series at the end of the eighth backslopping step were Lactobacillus hilgardii, Lactobacillus nagelii, Lactobacillus paracasei, Bifidobacterium aquikefiri, Saccharomyces cerevisiae, and Dekkera bruxellensis. These microbial communities were influenced by the water buffer capacity and had an impact on the substrate consumption and metabolite production during water kefir fermentation.