Co-culture Of Lactic Acid Bacteria Research Articles

Unlocking the potential of oil by-products: Investigating the influence of co-culture fermentation on phenolic acid degradation in side stream blends from oil and dairy industry

According to the newest trends in food waste management, the priority for valorisation of oil and dairy industry by-products was recognised. New approach of blending side streams of plant and animal origin has been proposed for obtaining future foods with improved nutritional value. Major obstacle in valorising sunflower seed cake (SSC) and whey (W) is their perishability and a relatively high content of phenolics contributing to, among others, protein indigestibility. In the study, a new approach of microwave pre-treatment applied for SSC and W blends was used. Its influence on phenolic acids and antioxidant properties after fermentation with co-culture of lactic acid bacteria and yeast was examined. Microwave drying of blends was longer than that of SSC affecting phenolic acids content. Fermentation by L. lactis and K. lactis caused pH decrease and increase in total acidity in 48 h effectively limiting the growth of bacterial contaminants. Fermentation decreased the content of phenolic acids, especially in blend composed of SSC and W (8.75:1; w/w) with the highest content of these constituents (from 1611.3 down to 838.8 mg/100 g dry matter). The study showed the synergistic effect of pre-treatment method and fermentation in terms of reduction in phenolic acids in new food matrices.

Protist–Lactic Acid Bacteria Co-Culture as a Strategy to Bioaccumulate Polyunsaturated Fatty Acids in the Protist Aurantiochytrium sp. T66

Thraustochytrids are aquatic unicellular protists organisms that represent an important reservoir of a wide range of bioactive compounds, such as essential polyunsaturated fatty acids (PUFAs) such as arachidonic acid (ARA), docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), which are involved in the regulation of the immune system. In this study, we explore the use of co-cultures of Aurantiochytrium sp. and bacteria as a biotechnological tool capable of stimulating PUFA bioaccumulation. In particular, the co-culture of lactic acid bacteria and the protist Aurantiochytrium sp. T66 induce PUFA bioaccumulation, and the lipid profile was evaluated in cultures at different inoculation times, with two different strains of lactic acid bacteria capable of producing the tryptophan dependent auxins, and one strain of Azospirillum sp., as a reference for auxin production. Our results showed that the Lentilactobacillus kefiri K6.10 strain inoculated at 72 h gives the best PUFA content (30.89 mg g-1 biomass) measured at 144 h of culture, three times higher than the control (8.87 mg g-1 biomass). Co-culture can lead to the generation of complex biomasses with higher added value for developing aquafeed supplements.

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.

Exploring the Potential of Lactic Acid Fermentation for the Recovery of Exhausted Vanilla Beans.

The market value of vanilla is constantly growing, as it is the aroma most appreciated by consumers worldwide. The key component of the aroma of vanilla beans is vanillin, which can be directly extracted from the plant, produced by chemical synthesis, or by bioconversion of natural precursors. Due to the increasing consumers' demand for products labeled as “natural,” extraction from vanilla pods results in a more valuable aroma source. Once the extraction is completed, what remains are the exhausted beans that still contain small seeds and other compounds, including varying amounts of vanillin trapped in the cellular structures of the plant. The application of fermentation of exhausted vanilla beans is proposed here as a strategy to recover “natural” vanillin and other valuable aroma compounds as a result of the metabolic conversion by lactic acid bacteria (LAB). The aim of this study was to verify the fermentability of exhausted vanilla beans by-products for their valorization, allowing the recovery of high-value molecules or new applications in food products. Design of Experiment (DoE) was used to screen a library of LAB strains to identify the best condition of fermentation in response to varying cultivation conditions. A comparison between mono and co-culture of LAB was assessed. Moreover, sensory panel tests and the evaluation of the aromatic components by Solid Phase Micro Extraction-Gas Chromatography-Mass Spectrometry analysis were carried out to better understand the modification of the aroma profile after fermentation. Fermentation with LAB changed the volatile profile and sensory characteristics of the exhausted vanilla beans and represents a promising method for the valorization of these by-products.

Mixed dairy and plant-based yogurt alternatives: Improving their physical and sensorial properties through formulation and lactic acid bacteria cocultures

Food transition requires incorporating more plant-based ingredients in our diet, thus leading to the development of new plant-based products, such as yogurt alternatives (YAs). This study aimed at evaluating the impact of lactic acid bacteria (LAB) cocultures and formulation on the physico-chemical and sensory properties of YAs. YAs were made by emulsifying anhydrous milk fat (AMF) or coconut oil in milk and lupin protein suspensions. The starters used, in mono- and cocultures, were the strains Lactococcus lactis NCDO2125, Enteroccocus faecalis CIRM-BIA2412 and Lactiplantibacillus plantarum CIRM-BIA1524. Textural properties and metabolites of YAs were evaluated and their sensory properties compared using a sorting task. Some cocultures led to higher firmness, viscosity, and water holding capacity of YAs, compared to monocultures. AMF and a milk:lupin protein ratio of 67:33 gave firmer and more viscous YAs. YAs were sensorially discriminated on the basis of protein ratio and fat type, but not of starters. The cocultures exhibited more diverse functional outputs, such as texturing, production of flavour compounds, proteolysis, when the strains associated in coculture had distinct capacities. Appropriate associations of LAB and formulation offer interesting solutions to improve the perception of YAs, and ultimately, encourage their consumption.

Effect of fermentation with single and co-culture of lactic acid bacteria on okara: evaluation of bioactive compounds and volatile profiles

Okara is the main soybean by-product resulting from the processing of soy milk and tofu. Despite being a product with a lot of potential and rich in many bioactive compounds such as polyphenols, it presents an unpleasant, rancid aroma. For this reason its use in the food industry is limited. In this study, we have reported the integral use of okara in a solid state fermentation process, conducted with wild strains of lactic acid bacteria, to evaluate the effect of bacterial metabolism on the volatile and polyphenolic profiles. Strains belonging to Lactobacillus acidophilus, Lacticaseibacillus rhamnosus and Pediococcus acidilactici species were used in monoculture and, for the first time, in co-culture. The results showed an improvement in the aromatic fraction showing a decrease in hexanal, responsible for off-flavour, and an increase in ketones with fruity and buttery notes in fermented okara. Polyphenols were also affected, and, in particular, a bioconversion of glucoside isoflavones to the aglycone forms was highlighted in all fermented substrates. In addition, the appearance of both phenyllactic and p-hydroxyphenyllactic acids as well as the increase in indole-3-lactic acid was observed for the first time upon okara fermentation. Overall, the co-culture appears to be the most promising for biovalorization of okara, thereby opening the possibility of its use in the development of functional ingredients.

Function-Driven Design of Lactic Acid Bacteria Co-cultures to Produce New Fermented Food Associating Milk and Lupin.

Designing bacterial co-cultures adapted to ferment mixes of vegetal and animal resources for food diversification and sustainability is becoming a challenge. Among bacteria used in food fermentation, lactic acid bacteria (LAB) are good candidates, as they are used as starter or adjunct in numerous fermented foods, where they allow preservation, enhanced digestibility, and improved flavor. We developed here a strategy to design LAB co-cultures able to ferment a new food made of bovine milk and lupin flour, consisting in: (i) in silico preselection of LAB species for targeted carbohydrate degradation; (ii) in vitro screening of 97 strains of the selected species for their ability to ferment carbohydrates and hydrolyze proteins from milk and lupin and clustering strains that displayed similar phenotypes; and (iii) assembling strains randomly sampled from clusters that showed complementary phenotypes. The designed co-cultures successfully expressed the targeted traits i.e., hydrolyzed proteins and degraded raffinose family oligosaccharides of lupin and lactose of milk in a large range of concentrations. They also reduced an off-flavor-generating volatile, hexanal, and produced various desirable flavor compounds. Most of the strains in co-cultures achieved higher cell counts than in monoculture, suggesting positive interactions. This work opens new avenues for the development of innovative fermented food products based on functionally complementary strains in the world-wide context of diet diversification.

Understanding the Mechanisms of Positive Microbial Interactions That Benefit Lactic Acid Bacteria Co-cultures.

Microorganisms grow in concert, both in natural communities and in artificial or synthetic co-cultures. Positive interactions between associated microbes are paramount to achieve improved substrate conversion and process performance in biotransformation and fermented food production. The mechanisms underlying such positive interactions have been the focus of numerous studies in recent decades and are now starting to be well characterized. Lactic acid bacteria (LAB) contribute to the final organoleptic, nutritional, and health properties of fermented food products. However, interactions in LAB co-cultures have been little studied, apart from the well-characterized LAB co-culture used for yogurt manufacture. LAB are, however, multifunctional microorganisms that display considerable potential to create positive interactions between them. This review describes why LAB co-cultures are of such interest, particularly in foods, and how their extensive nutritional requirements can be used to favor positive interactions. In that respect, our review highlights the benefits of co-cultures in different areas of application, details the mechanisms underlying positive interactions and aims to show how mechanisms based on nutritional interactions can be exploited to create efficient LAB co-cultures.

Sensory Improvement of a Pea Protein-Based Product Using Microbial Co-Cultures of Lactic Acid Bacteria and Yeasts.

Consumer demands for plant-based products have increased in recent years. However, their consumption is still limited due to the presence of off-flavor compounds, primarily beany and green notes, which are mainly associated with the presence of aldehydes, ketones, furans, and alcohols. To overcome this problem, fermentation is used as a lever to reduce off-flavors. A starter culture of lactic acid bacteria (LAB) was tested in a 4% pea protein solution with one of the following yeasts: Kluyveromyces lactis, Kluyveromyces marxianus, or Torulaspora delbrueckii. The fermented samples were evaluated by a sensory panel. Non-fermented and fermented matrices were analyzed by gas chromatography coupled with mass spectrometry to identify and quantify the volatile compounds. The sensory evaluation showed a significant reduction in the green/leguminous attributes of pea proteins and the generation of new descriptors in the presence of yeasts. Compared to the non-fermented matrix, fermentations with LAB or LAB and yeasts led to the degradation of many off-flavor compounds. Moreover, the presence of yeasts triggered the generation of esters. Thus, fermentation by a co-culture of LAB and yeasts can be used as a powerful tool for the improvement of the sensory perception of a pea protein-based product.

Nondairy beverage produced by controlled fermentation with potential probiotic starter cultures of lactic acid bacteria and yeast

This work aimed to develop a nondairy fermented beverage from a blend of cassava and rice based on Brazilian indigenous beverage cauim using probiotic lactic acid bacteria (LAB) and yeast. The indigenous strains Lactobacillus plantarum CCMA 0743 (from cauim) and Torulaspora delbrueckii CCMA 0235 (from tarubá), and the commercial probiotic, L. acidophilus LAC-04, were used as starter cultures in single and co-cultivations. The bacteria populations were around 8.0 log (CFU/mL) at the end of all fermentations as recommended for probiotic products. Higher residual starch contents were noted in the single LAB cultures (10.6% [w/w]) than in co-cultures (<6% [w/w]), showing that co-culture may help the digestibility. For all different assays (single and co-culture), lactic acid was the main organic acid detected (>1.6g/L) and ethanol was lower than 0.5% (w/v) consisting in a non-alcoholic beverage. The assays containing yeast showed the highest antioxidant activity (around 10% by DPPH and ABTS methods). Therefore, a nondairy fermented beverage was successfully obtained, and the co-culture of LAB and T. delbrueckii could increase the product's functional properties.

Analysis of gene expression profiles of Lactobacillus paracasei induced by direct contact with Saccharomyces cerevisiae through recognition of yeast mannan.

Co-culture of lactic acid bacteria (LAB) and yeast induces specific responses that are not observed in pure culture. Gene expression profiles of Lactobacillus paracasei ATCC 334 co-cultured with Saccharomyces cerevisiae IFO 0216 were analyzed by DNA microarray, and the responses induced by direct contact with the yeast cells were investigated. Coating the LAB cells with recombinant DnaK, which acts as an adhesive protein between LAB and yeast cells, enhanced the ratio of adhesion of the LAB cells to the yeast cells. The signals induced by direct contact were clarified by removal of the LAB cells unbound to the yeast cells. The genes induced by direct contact with heat-inactivated yeast cells were very similar to both those induced by the intact yeast cells and those induced by a soluble mannan. The top 20 genes upregulated by direct contact with the heat-inactivated yeast cells mainly encoded proteins related to exopolysaccharide synthesis, modification of surface proteins, and transport systems. In the case of the most upregulated gene, LSEI_0669, encoding a protein that has a region homologous to polyprenyl glycosylphosphotransferase, the expression level was upregulated 7.6-, 11.0-, and 8.8-fold by the heat-inactivated yeast cells, the intact yeast cells, and the soluble mannan, respectively, whereas it was only upregulated 1.8-fold when the non-adherent LAB cells were not removed before RNA extraction. Our results indicated that the LAB responded to direct contact with the yeast cells through recognition of mannan on the surface of the yeast.

Identification of lactic acid bacteria strains modulating incretin hormone secretion and gene expression in enteroendocrine cells

Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are incretin hormones released from intestinal enteroendocrine (EE) cells and have well-established glucose-lowering actions. Lactic acid bacteria (LAB) colonise the human intestine, but it is unknown whether LAB and EE cells interact. Acute co-culture of LAB with EE cells showed that certain LAB strains elicit GLP-1 and GIP secretion (13-194-fold) and upregulate their gene expression. LAB-induced incretin hormone secretion did not appear to involve nutrient mechanisms, nor was there any evidence of cytolysis. Instead PCR array studies implicated signalling agents of the toll-like receptor system, e.g. adaptor protein MyD88 was decreased 23-fold and cell surface antigen CD14 was increased 17-fold. Mechanistic studies found that blockade of MyD88 triggered significant GLP-1 secretion. Furthermore, blocking of CD14 completely attenuated LAB-induced secretion. A recent clinical trial clearly shows that LAB have potential for alleviating type 2 diabetes, and further characterisation of this bioactivity is warranted.

Antioxidant Activity of Peptides from Fermented Milk with Mix Culture of Lactic Acid Bacteria and Yeast

The aim of the present study is to investigate the production of antioxidant peptides during milk fermentation with co-culture of Lactic Acid Bacteria (LAB) and yeast. Five LAB strains, previously screened with higher hydrolysis activity and <em>Debaryomyces hansenii</em> H2 which isolated from Tibet kefir were used in the study. The peptides separated from fermented milk were analysed antioxidant activity with DPPH radical scavenging, hydroxyl radical scavenging, chelation of metal ions and reducing power assays. The growth of <em>Streptococcus</em>. <em>thermophilus</em>, <em>Lactobacillus</em>. <em>delbrueckii</em> ssp. bulgaricus and <em>Lactococcus</em>. <em>lactis</em> was enhanced with co-cultures and L. acidophilus was inhibited in co-culture with yeast. In co-culture with yeast, a significant decrease of the acidity was observed among all the fermentation and the pH reached higher values than in single LAB cultures. Except for <em>L.delbrueckii</em> ssp. bulgaricus, there was no significant difference of protein hydrolysis with other test LAB strains between co-culture and single culture. The co-incubation of LAB with the yeast developed a stronger antioxidant activity in DPPH radical and hydroxyl radical scavenging and no significant (p>0.05) difference in chelation of metal ions. The reducing power of <em>L. delbrueckii</em> ssp. bulgaricus and <em>L. helveticus</em> in co-culture was significant higher than those of single culture.

The effect of process parameters in enhancement of lipase production by co-culture of lactic acid bacteria and their mutagenesis study

Abstract Microbial consortium of various microorganisms has been applied in many fields of biotechnology but its application for the production of lipase is yet to be explored more. The objective of this work was to select the best possible combination of lipase producing bacteria of Lactococcus lactis and Lactobacillus brevis, or Lactococcus lactis and Lactobacillus plantarum, or Lactobacillus brevis and Lactobacillus plantarum for the optimum production of this enzyme using olive oil as a substrate. The co-culture of Lactobacillus brevis and Lactobacillus plantarum produced highest activity of 37 U/ml than other organisms. All the cultures were subjected to UV, heat and EtBr mutagenesis. A few colonies were screened from the selected media for lipase study. Amongst all, the best mutant was isolated after 120 min of UV treatment where there is increase in number of colonies and enzyme activity.

The growth and interaction of yeasts and lactic acid bacteria isolated from Zimbabwean naturally fermented milk in UHT milk

Nine yeast and four lactic acid bacterial strains, previously isolated from Zimbabwean traditionally fermented milk, were inoculated into ultra-high temperature treated (UHT) milk in both single and yeast–lactic acid bacteria co-culture. The lactic acid bacteria (LAB) strains consisted of Lactococcus lactis subsp. lactis biovar. diacetylactis C1, L. lactis subsp. lactis Lc39, L. lactis subsp. lactis Lc261 and Lactobacillus paracasei subsp. paracasei Lb11. The yeast strains used were Candida kefyr 23, C. lipolytica 57, C. lusitaniae 63, C. lusitaniae 68, C. tropicalis 78, Saccharomyces cerevisiae 71, S. dairenensis 32, C. colliculosa 41 and Dekkera bruxellensis 43. After 48-h fermentation at 25°C, the samples were analysed for pH, viable yeast and bacterial counts, organic acids, volatile organic compounds (VOC) and carbon dioxide. The Lactococcus strains reduced the pH from about 6.6 to between 4.0 and 4.2, while Lb. paracasei subsp. paracasei Lb11 reduced the pH to about 5.4. Most of the yeasts, however, did not affect the final pH of the milk except for C. kefyr 23, which reduced the pH from 6.6 to 5.8. All the Lactococcus strains grew two log cycles during the 48-h fermentation period, while Lb. paracasei subsp. paracasei Lb11 grew about one log cycle. S. cerevisiae 71, C. colliculosa 41 and D. bruxellensis 43 showed poor growth in the milk in both single and co-culture. The other species of yeast grew about two log cycles. Candida colliculosa 41, S. dairenensis 32 and D. bruxellensis 43 showed reduced viability when in co-culture with Lb. paracasei subsp. paracasei Lb11. The samples in which C. kefyr 23 was used were distinct and characterised by large amounts of acetaldehyde, carbon dioxide and ethanol. However, in the samples where S. dairenensis, C. colliculosa, D. bruxellensis, C. lusitaniae, C. tropicalis, C. lipolytica and S. cerevisiae were used in co-culture, the final pH and metabolite content were mainly determined by the corresponding LAB strain. From the observations, it was concluded that C. kefyr 23 grows well in UHT milk and produces VOC that may be important to the flavour profile of the fermented milk. Enhancement of production of some flavour compounds such as acetaldehyde and malty compounds in some yeast–LAB co-cultures was presumed to be indicative of interaction between the microorganisms.

Does gene horizontal transfer occur in lactic acid bacteria co-cultures?

Quatre types differents de sequences d'insertion, IS1191, IS981, ISS1 et IS1194 ont ete caracterises chez S. thermophilus CNRZ368. Les elements ISS1 peuvent etre repartis en trois sous-groupes, α, β et y, dont les sequences divergent de 15 a 25 % et des elements mosaiques resultant de la recombinaison d'ISS1 de sous-groupes differents. Les sequences nucleotidiques de types IS1191, IS981, ISS1 α et β de S. thermophilus CNRZ368 sont presque identiques a celles des elements homologues de L. lactis, suggerant que des transferts horizontaux se sont produits recemment entre ces deux especes bacteriennes. La distribution de ces elements suggere que des transferts horizontaux se seraient produits dans les deux sens lors des cocultures de ces deux especes utilisees dans les fabrications fromageres. De plus, IS1194 aurait egalement ete acquise chez les deux especes par des transferts horizontaux a partir d'une espece bacterienne non identifiee. Les trois copies d'ISS1, deux des quatre copies d'IS981 et l'unique copie d'IS1194 de S. thermophilus CNRZ368 sont regroupees dans un fragment chromosomique de 12 kb qui pourrait avoir ete acquis par transfert horizontal a partir de L. lactis. Les transferts d'IS et d'autres genes comme citP codant la citrate permease concernent des especes appartenant a cinq genres differents de bacteries lactiques, Lactococcus, Streptococcus, Lactobacillus, Leuconostoc et Enterococcus.