Lactic Acid Bacteria Cultures Research Articles

STUDY OF ANTIBIOTIC RESISTANCE OF LACTIC ACID BACTERIA ISOLATED FROM DAIRY PRODUCTS

In this study, cultures of lactic acid bacteria (3M, 3K, 7K, 9K, 10K and 11K) isolated from mare's milk and koumiss were examined in order to assess their resistance to various antibiotics. Discs impregnated with gentamicin (120 mcg), azithromycin (15 mcg), ceftriaxone (30 mcg), cefuroxime (30 mcg) and chloramphenicol (30 mcg) were used.The data obtained showed that strains 3K, 10K and 11K demonstrated the greatest resistance to gentamicin, similarly, strains 10K and 11K showed high resistance to azithromycin. For ceftriaxone and cefuroxime, strains 11K and 10K demonstrated the greatest resistance. Strains 11K and 10K were the most resistant to chloramphenicol, while strain 3K was the most sensitive. In general, strains 3K and 3M showed the least resistance to most antibiotics, especially ceftriaxone and cefuroxime, which indicates their high sensitivity to these drugs. In contrast, strains 10K and 11K demonstrated the greatest resistance, showing minimal suppression zones for most of the antibiotics studied.The obtained data can be used to develop and optimize probiotic drugs that take into account the resistance of lactic acid bacteria to antibiotics. This will increase the effectiveness of the use of probiotics in various foods and medicines, contributing to the maintenance of healthy intestinal microflora and strengthening the immune system.

Clear zone formation in microdroplets for high-throughput screening for lactic acid bacteria.

Droplet microfluidic-based technology is a powerful tool for biotechnology, and it is also expected that it will be applied to culturing and screening methods. Using this technology, a new high-throughput screening method for lactic acid bacteria was developed. In this study, the conventional culture of lactic acid bacteria that form clear zones on an agar medium was reproduced in water-in-oil droplets, and only the droplets in which lactic acid bacteria grew were collected one by one. Using this method, the specific recovery of Lactiplantibacillus plantarum from a mixture of L. plantarum and Escherichia coli and the acquirement of lactic acid bacteria from an environmental sample were successful. This method could be applied to various conventional screening methods using the clear zone as a microbial growth indicator. This has expanded the possibilities of applying droplet microfluidic-based technology to microbial cultivations.

Serine and threonine activate Ser/Thr kinase gene to increase the density of Lactobacillus bulgaricus sp1.1 under salt stress

Salt stress significantly impedes high cell-density culture by suppressing the reproductive capacity of lactic acid bacteria. This study examined the effects of salt stress conditions (2% w/v NaCl) on Lactobacillus bulgaricus sp1.1. Although DNA replication and division ring localization remained unaffected, the down-regulation of the ftsZ and dnaA genes inhibited division ring assembly. Consequently, bacteria exhibited filamentation, increased cell length, and accumulated chromosomes and division rings, which obstructed cell division. Under salt stress, sp1.1 experienced several transcriptional changes. The serine/threonine kinase gene was identified as a significant regulator of bacterial division under salt stress. Exogenous addition of serine and threonine could stimulate the expression of Ser/Thr kinase gene, promote the assembly of division ring, and enhance the dividing ability of the bacterium, which led to a density of 7.93 log CFU/mL under the salt stress, which was 6.92 times higher than that of the untreated group. This study provides a new perspective for high-density cultivation of lactic acid bacteria.

Lactiplantibacillus plantarum I Induces Gonad Growth in the Queen Scallop Aequipecten opercularis (Linnaeus, 1758) under Conditions of Climate Change

Climate change has presented a serious problem in recent times, which is why a new approach is being sought in terms of aquacultural food quality. In this study, the influence of temperature increase (by 2 °C) and pH decrease (by 0.2) was investigated on the queen scallop, Aequipecten opercularis (Linnaeus, 1758). Furthermore, the effect of a food-enriched diet with the probiotic culture Lactiplantibacillus plantarum I was assessed in climate-changed conditions. Scallops’ morphometric parameters were measured before the experimental setup and after one month of being kept in controlled conditions. Morphometric parameters included the elongation index, compactness index, convexity index, density index, condition index, meat yield, gonadosomatic index, adductor muscle index, and hepatosomatic index. Climate-changed conditions had no effect on the scallop condition index, meat yield, or hepatosomatic index. Nevertheless, the addition of probiotics to their diet had a positive effect on the queen scallops cultivated under conditions of climate change, influencing positive allometry and the increase of the gonadosomatic indices. On the other hand, the same conditions negatively affected the adductor muscle index of the scallops. To conclude, in the context of climate change conditions, queen scallops could be a good organism of choice that can be very well adapted to the changed environmental conditions, especially with the addition of the lactic acid bacteria culture Lpb. plantarum I.

Investigation of the influence of milk protein genotype on the process of fermentation of milk curds by mesophilic lactic acid streptococci

The relevance of this study lies in the fact that the majority of commercial milk processed into fermented dairy products is a mixture of β-casein genotypes. The increasing use of A2 milk in the dairy industry necessitates the development of scientifically grounded technologies for the production of fermented products, as casein genotype modifications can affect the course of technological processes and require adjustments to production parameters. The study aimed to determine the impact of genetic modification of the β-casein protein in cow’s milk on the fermentation process of milk mixtures during the production of fermented dairy products. Research methods included chemical, physical, organoleptic, and microbiological methods (determination of the quality indicators of raw milk and fermented milk curds), and technological methods (determination of acid formation activity and viscosity). The initial characteristics of raw milk were investigated according to genotype, revealing no direct correlation. Changes in the physicochemical, microbiological, and organoleptic properties of fermented milk curds during biotechnological processing and storage were examined. Optimal technological process regimes were selected, and technological methods were chosen to minimise the influence of secondary factors on the experiment. A mixed culture preparation of mesophilic lactic acid lactococci, including L. Lactis ssp., was chosen as a starter culture. It was established that all 13 milk samples were suitable for biotechnological processing using mixed cultures of mesophilic lactic acid bacteria. As a result, it was concluded that the production of fermented dairy products from raw milk with the presented β-casein genetic modifications, A1A1, A1A2, and A2A2 – using L. lactis ssp. cultures – is possible using the classical technology and does not require adjustment of the technological conditions. The obtained results can be used in the dairy industry when developing technologies for fermented dairy products from A2 raw milk

Fermentation of Rice, Oat, and Wheat Flour by Pure Cultures of Common Starter Lactic Acid Bacteria: Growth Dynamics, Sensory Evaluation, and Functional Properties.

Recent consumer demand for non-dairy alternatives has forced many manufacturers to turn their attention to cereal-based non-alcoholic fermented products. In contrast to fermented dairy products, there is no defined and standardized starter culture for manufacturing cereal-based products. Since spontaneous fermentation is rarely suitable for large-scale commercial production, it is not surprising that manufacturers have started to adopt centuries-known dairy starters based on lactic acid bacteria (LABs) for the fermentation of cereals. However, little is known about the fermentation processes of cereals with these starters. In this study, we combined various analytical tools in order to understand how the most common starter cultures of LABs affect the most common types of cereals during fermentation. Specifically, 3% suspensions of rice, oat, and wheat flour were fermented by the pure cultures of 16 LAB strains belonging to five LAB species-Lacticaseibacillus paracasei, Lactobacillus delbrueckii, Lactobacillus helveticus, Streptococcus thermophilus, and Lactococcus lactis. The fermentation process was described in terms of culture growth and changes in the pH, reducing sugars, starch, free proteins, and free phenolic compounds. The organoleptic and rheological features of the obtained fermented products were characterized, and their functional properties, such as their antioxidant capacity and angiotensin-converting enzyme inhibitory activity, were determined.

Chemical composition of sausages processed with starter cultures Lactobacillus curvatus and Lactococcus lactis subsp. lactis during storage in vacuum packaging

Sausages belong to the category of cooked meat products with a short shelf life, which is associated with their rapid spoilage and unsuitability for consumption. One of the ways to extend the shelf life of sausages is the use of biopreservatives, including cultures of lactic acid bacteria. The aim of the study was to determine the chemical composition and organoleptic characteristics of "Juicy" sausages processed with a starter culture of Lactobacillus curvatus or a mixture of starter cultures Lactobacillus curvatus + Lactococcus lactis subsp. lactis before vacuum packaging and storage in a chilled state. Storage of sausages in the control variant in vacuum packaging in a chilled state for up to 18 days did not affect the moisture, protein, fat, and ash content, but on the 21st day, their spoilage was observed in the form of appearance of cloudy juice, sliminess, sour odor, and delamination of the vacuum packaging. Processing sausages with a starter culture of Lactobacillus curvatus or a mixture of starter cultures Lactobacillus curvatus + Lactococcus lactis subsp. lactis before vacuum packaging did not affect the moisture, protein, fat, and ash content up to 30 days of storage in a chilled state. On the 36th day, spoilage of sausages was observed in both variants of treatment with lactic acid bacteria cultures, characterized by the appearance of cloudy juice, sour odor, and delamination of the vacuum packaging. The pH value of sausages in both variants of treatment with lactic acid bacteria cultures decreased throughout the storage period and reached a level of 6.05 and 5.91 units on the 30th day. Processing sausages with either a single culture or a mixture of lactic acid bacteria cultures extends their shelf life in a chilled state by 12 days. The obtained results may justify the use of microbial biopreservatives for the production of cooked sausage products, which will help reduce losses due to spoilage during storage in vacuum packaging in a chilled state. The use of a mixture of lactic acid bacteria cultures for processing sausages requires further research and may be effective in case of detection of aerobic spoilage microorganisms.

Screening of Lactic Acid Bacteria for Silage Inoculant Candidate

Abstract Silage fermentation is generally assisted by lactic acid bacteria (LAB). The aim of this study was to screen selected LABs for silage inoculant. A total of 60 LAB isolates from the Indonesian Culture Collection (InaCC) were used in this study. Screening was carried out in an MRS broth medium using three different substrates, which were glucose, sucrose, and carboxyl methyl cellulose (CMC). The supernatant from LAB cultures was tested for pH, lactic acid (LA) concentration, antimicrobial activity, and cellulolytic activity. The results of the screening obtained 4 LAB isolates to be used as silage inoculant. Three LAB isolates selected from the glucose substrate were Lactobacillus fermentum InaCC-B1024, Lactobacillus plantarum InaCC-B1028, and L. brevis InaCC-B1052. Lactobacillus fermentum InaCC B1024 has a pH, LA concentration, cellulolytic activity, and percentage inhibition of 3.71, 318.931 mM, and 0.806 U/mL, > 95% antibacterial inhibition against B. subtilis, S. auerus, K. michiganensis, S. lloydii, and S. gallinarum, and <35% antifungal activity against M. ramosissimus, A. flavus, F. oxysporum, and P. griseofulvum, respectively. L. plantarum InaCC-B1028 has a pH, LA concentration, cellulolytic activity, and percentage activity of 3.61, 318.833 mM, 0.866 U/ml, > 95% antibacterial activity against B. subtilis, E. coli, M. luteus, S.auerus, K. michiganensis, S.lloydii, S. gallinarum, and < 40% antifungal activity against M. ramosissimus, A. flavus, F. oxysporum, and P. griseofulvum, respectively. L. brevis InaCC-B1052 has a pH, LA concentration, cellulolytic activity, and percentage activity of 3.67, 301.676 mM, no cellulolytic activity, > 95% antibacterial activity against E. coli, M. luteus, S. auerus, K. michiganensis, S. lloydii, S. gallinarum, and < 25% antifungal activity against M. ramosissimus and A. flavus, respectively. One LAB isolate selected from sucrose was L. kimchii InaCC-B982. Its pH, LA concentration, cellulolytic activity, and percentage activity were 3.77, 285.5 mM, 7.288 U/mL, > 95% antibacterial activity against E. coli, M. luteus, S. auerus, K. michiganensis, S. lloydii, S. gallinarum, and <15% antifungal activity against M. ramosissimus, A. flavus, F. oxysporum, and P. griseofulvum, respectively. Based on the results, the four LABs could be used as silage inoculant candidates.

Cleaner anaerobic fermentation and greenhouse gas reduction of crop straw.

Rice anaerobic fermentation is a significant source of greenhouse gas (GHG) emissions, and in order to efficiently utilize crop residue resources to reduce GHG emissions, rice straw anaerobic fermentation was regulated using lactic acid bacteria (LAB) inoculants (FG1 and TH14), grass medium (GM) to culture LAB, and Acremonim cellulolyticus (AC). Microbial community, GHG emission, dry matter (DM) loss, and anaerobic fermentation were analyzed using PacBio single-molecule real-time and anaerobic fermentation system. The epiphytic microbial diversity of fresh rice straw was extremely rich and contained certain nutrients and minerals. During ensiling, large amounts of GHG such as carbon dioxide are produced due to plant respiration, enzymatic hydrolysis reactions, and proliferation of aerobic bacteria, resulting in energy and DM loss. Addition of FG1, TH14, and AC alone improved anaerobic fermentation by decreasing pH and ammonia nitrogen content (P < 0.05) and increased lactic acid content (P < 0.05) when compared to the control, and GM showed the same additive effect as LAB inoculants. Microbial additives formed a co-occurrence microbial network system dominated by LAB, enhanced the biosynthesis of secondary metabolites, diversified the microbial metabolic environment and carbohydrate metabolic pathways, weakened the amino acid metabolic pathways, and made the anaerobic fermentation cleaner. This study is of great significance for the effective utilization of crop straw resources, the promotion of sustainable livestock production, and the reduction of GHG emissions.IMPORTANCETo effectively utilize crop by-product resources, we applied microbial additives to silage fermentation of fresh rice straw. Fresh rice straw is extremely rich in microbial diversity, which was significantly reduced after silage fermentation, and its nutrients were well preserved. Silage fermentation was improved by microbial additives, where the combination of cellulase and lactic acid bacteria acted as enzyme-bacteria synergists to promote lactic acid fermentation and inhibit the proliferation of harmful bacteria, such as protein degradation and gas production, thereby reducing GHG emissions and DM losses. The microbial additives accelerated the formation of a symbiotic microbial network system dominated by lactic acid bacteria, which regulated silage fermentation and improved microbial metabolic pathways for carbohydrates and amino acids, as well as biosynthesis of secondary metabolites.

Enrichment and Characterization of Sheep Caecum Mixed Lactic Acid Bacteria as Potential Direct-fed Microbials (DFMs) in Livestock

Abstract Lactic Acid Bacteria (LAB) have been widely used as feed supplements in the form of live bacteria or Direct-fed microbials (DFMs) which are expected to have a positive impact on livestock productivity. However, each LAB strain has different characteristics so its ability to influence its host livestock will also be different. This research aims to characterize the LAB enrichment process obtained from the caecum of sheep. The sheep caecum LAB underwent re-inoculated while being enriched in MRS broth medium. After obtaining the LAB isolates, characterization was carried out in the form of pH measurements, total plate count, bacteriocin production, and bacterial kinetic growth. The results showed that LAB could be grown from the digesta of sheep caecum as seen from the decrease in the average pH of the growth medium reaching pH 4.14 with a bacterial colony count of 6,01 log CFU/ml. The grown LAB had a Ks value of 0.24 μM glucose and a μmax value of 2.69 OD. Apart from that, the clear zone test showed a positive result. In conclusion, Enrichment of mixed LAB cultures from sheep caecum has decreased environmental pH by 33%. Sheep caecum mixed LAB culture has easy growth characteristics and antimicrobial activity so it can be a suitable alternative DMF candidate. Further research focusing on the application of this LAB strain is needed to be able to determine the effect of bacteria on livestock.

Effects of exogenous autoinducer-2 precursor on the ability of Lactiplantibacillus plantarum SH7 to degrade biogenic amines: In vitro and in a dry-sausage model

The effects of the exogenous autoinducer-2 (AI-2) precursor, 4,5-dihydroxy-2,3-pentanedione (DPD; 0, 300, 600, and 900 nmol/L), on the degradation capacity of Lactiplantibacillus plantarum SH7 toward biogenic amines (BA) were investigated both in vitro and in a dry-sausage model. L. plantarum SH7 exhibited a significant increase in BA-degradation capacity (putrescine, cadaverine, and histamine) under DPD treatments compared to the absence of DPD treatment in vitro. Additionally, a significant increase in the production of AI-2 signal molecule and diamine oxidase in L. plantarum SH7 was observed with the addition of exogenous DPD (p < 0.05). In the dry-sausage model, the contents of BAs (tryptamine, 2-phenethylamine, putrescine, cadaverine, and histamine) significantly decreased with the addition of DPD (p < 0.05). Meanwhile, the sausage with 600-nM DPD exhibited the lowest cadaverine content (11.13 mg/kg), while the sausage with 900-nM DPD exhibited the lowest tryptamine, putrescine, and histamine contents (12.44, 11.15, and 13.21 mg/kg, respectively). Results suggest that an optimal concentration of exogenous DPD can enhance the capacity of L. plantarum SH7 to degrade BAs and that the degradation of BAs by L. plantarum SH7 may be dependent on the LuxS/AI-2 quorum sensing (QS) system. This study provides the theoretical basis for the development of functional starter cultures of lactic acid bacteria with BA-degradation ability based on targeted LuxS/AI-2 QS system regulation and reducing the accumulation of BAs in fermented meat products.

Development of a defined mixed starter culture for the improvement of Tej, Ethiopian honey wine.

Ethiopian honey wine, Tej, is the most popular traditionally fermented alcoholic beverage in Ethiopia. Owing to the spontaneous fermentation process, the final product is neither predictable nor consistent in quality. Attempts have not been made before to solve this problem. Thus, the aim of this study was to develop a potential mixed starter culture of yeast and lactic acid bacteria isolated from Tej samples for the production of Tej with consistent quality. One hundred seventy-seven lactic acid bacteria and 194 yeasts were isolated from 30 Tej samples collected from southwest Ethiopia. After sequentially testing the isolates towards physiological stress tolerance and desired metabolic products, 10 lactic acid bacteria and 10 yeast isolates were screened. Later, four lactic acid bacteria and four yeast isolates were found to be compatible in co-culture tests. Finally, the combination of lactic acid bacteria and yeast isolates was formulated using the design of expert version 7.0.0 software, and six formulates (F #1-6) were designed. Controlled Tej fermentation was performed under laboratory conditions using six lactic acid bacteria-yeast starter culture formulations. The sensory attributes, in terms of color, flavor, odor, turbidity, and overall acceptance analysis scored 4.8/5.0 (F #2) and 4.7/5.0 (F #6), with mean significant variations (p < 0.05) among the other formulates. These two formulates were considered the best-mixed starter cultures compared to the control and other formulates. Matrix-assisted laser desorption ionization-time of flight analysis revealed that the lactic acid bacteria starters (AAUL7 and AAUL10) belonged to Lactobacillus paracasei. While the yeast starters (AAUY2 and AAUY8) belonged to Saccharomyces cerevisiae. These mixed lactic acid bacteria-yeast starter cultures could be used as the best starter culture for the fermentation of Ethiopian honey wine, Tej, with consistent quality.

Inactivation efficacy of four commercial post-process treatments against Listeria monocytogenes and impact on the commercial quality of leafy greens

The problem of product contamination with human pathogenic microorganisms is still unsolved. Although prevention through the implementation of good agricultural practices and good manufacturing practices is the gold standard, product decontamination strategies can be used to complement preventive measures. Different bioprotective treatments have been suggested to reduce the risk of listeriosis in fresh produce, but more information is needed before industrial implementation. This study focused on the efficacy of four commercial treatments against Listeria monocytogenes growth and their effect on the organoleptic quality of baby spinach, cut romaine, cut iceberg, and shredded cabbage. The treatments included SafePro® (CHR Hansen, DK) and Holdbac® (DowDuPont, US), based on the use of lactic acid bacteria (LAB) cultures as well as two different bacteriophage solutions, ListShield (Intralytix, US) and PhageGuard Listex™ (PhageGuard, US). The selected treatments were tested under simulated commercial conditions. The application was performed after processing and before packaging using a fine mist spray. In all the trials, Listex™ showed the best results in reducing L. monocytogenes growth during shelf life in the four leafy greens chosen. Microbial reductions were close to 2 log units. L. monocytogenes reductions were observed 1 day after Listex™ application and the efficacy was maintained during storage (15 days at 7 °C). Organoleptic quality, including flavor, texture, browning/yellowing, decay, and visual appearance of the four leafy greens was not significantly affected by the application of Listex™ when compared to the untreated products. Post-process treatment with Listex™ based on bacteriophages effectively reduced L. monocytogenes and can be recommended as a control tool to reduce the risks for the presence of L. monocytogenes in leafy greens.

Characteristics of fermentation changes in the dough for rye-wheat bread with the addition of propionic and lactic acid bacteria

The quality of bread directly depends on several physical and chemical indicators of the quality of flour, which is used in the technology of making products. Various types of flour, phyto-additives, oils, and leavening microorganisms are added to its recipe to improve the quality and increase the biological value of bread. Pure cultures of lactic acid and propionic acid bacteria are among the fermenting microbiota most often used in the technological process of bread production. The work aimed to determine the effect of adding pure cultures of lactic acid and propionic acid bacteria on the technological process of bread production. Three samples of dough and dough were prepared: the first with lactic acid bacteria and yeast; the second – propionic and lactic acid bacteria and yeast; the third only on a yeast base. Then, samples of rye-wheat dough were mixed in these ovens, and bread was baked. The symbiotic effect of propionic acid bacteria on the acidification of the environment, that is, on the development of yeast and lactic acid bacteria, was established because it was sample № 2 in which this entire microbial landscape was present that had the highest acidity of the dough. An interdependent relationship between added bacteria to the wort and reduction in fermentation time was revealed. In test № 2, the time required to reach the final fermentation process was about 77 min, about 30 min faster than in the control test. In dough № 2 with added microbiota, the lifting force time was the lowest. Therefore, the addition of propionic and lactic acid bacteria to the dough at the same time as yeast contributes to the active gas-forming ability of the dough. Thus, introducing this microbiota into the steam will increase semi-finished products in a short production time.

Lactic Acid Bacteria Isolates and the Microbiome of Cincalok, Tempoyak, and Mandai: A Traditional Fermented Food from Kalimantan Island, Indonesia.

Indonesia has abundant traditional fermented food with various lactic acid bacteria (LAB), which can be developed into probiotics for pharmaceutical and functional food and feed products. This research is aimed at (1) obtaining and identifying LAB isolates and (2) studying the microbiome (bacterial diversity and abundance) of spontaneously-fermented traditional foods of Kalimantan Island, Cincalok, Tempoyak, and Mandai. To obtain LAB isolates, food samples were serially diluted and inoculated on MRS agar that contained 1% CaCO3 (MRSA). Isolates forming clear zones were purified and identified by DNA barcoding. The microbiome was studied using genomic-sequencing techniques and analysed for taxonomic composition. Seven pure isolates were obtained from Cincalok, two Tempoyak, and one Mandai. DNA barcoding revealed that the Cincalok seven isolates were Staphylococcus carnosus (strain HSP-S16), Tetragenococcus halophilus (FSB201), Corynebacterium phoceense, Vagococcus vulneris (SS1995), Enterococcus faecalis (S11-6), Pisciglobus halotolerans (C01), and Priestia filamentosa (P3.1); two from Tempoyak, Levilactobacillus brevis (E1D3BL1) and Lactiplantibacillus plantarum (UMCC-2996); and one from Mandai, Staphylococcus cohnii (XAAS.x13; non-LAB). The T. halophilus, E. faecalis, P. halotolerans, L. brevis, and L. plantarum belong to LAB. The P. halotolerans from Cincalok and non-LAB in these three fermented foods were the first documented report. The microbiome revealed the dominance of Firmicutes phyla in the fermented foods, with 93% in Cincalok, 89.94% in Tempoyak, and 60.32% in Mandai. On the genus level, Cincalok was dominated by Tetragenococcus 40.33%, Anaerococcus 23.29%, Vagococcus 9.27%, and Lactobacillus 6.84%. Meanwhile, Tempoyak was dominated only by Lactobacillus 89.94%. Mandai were dominated by Lactobacillus 31.97%, Proteus 17.14%, Aerococcus 16.85%, Mangrovibacter 15.15%, and Vagococcus 6.2%. However, Mandai's microbiome LAB was not culturable/isolated on MRSA. The plausibility is that those unculturable LAB require coculturing with other bacteria and additional media components to grow on MRSA. This study is the first report regarding the microbiome of Cincalok, Tempoyak, and Mandai, along with their culturable LAB isolates.

Correlation between the bacterial flora and sensory quality of Bayannur sour porridge

In this study, the bacterial flora structure, sensory quality and culturable lactic acid bacteria resources of sour porridge in Bayannur area were analyzed. Furthermore, these bacterial sequencing data were combined with the high-throughput sequencing data of Ordos sour porridge to analyze the microbiota differences. MiSeq results showed that Lactiplantibacillus, Acetobacter, Lacticaseibacillus, Lactobacillus, and Limosilactobacillus were the main bacterial genera in sour porridge. Further comparative analysis showed that the average relative abundance of 7 dominant bacteria genera was significantly higher in sour porridge from Bayannur area (P < 0.05). Electronic nose and electronic tongue demonstrated that the primary volatile flavor substances in sour porridge were terpene compounds, and the change in taste characteristics was mainly reflected in the sour taste index. Correlation showed that most of LAB genera and Acetobacter were positively correlated with the formation of aromatic compounds. Pure culture showed that Lacticaseibacillus paracasei and Lactiplantibacillus plantarum were the dominant LAB in sour porridge. Overall, certain differences in the bacterial flora of sour porridge from different regions were identified, with Lactiplantibacillus, Acetobacter, Lacticaseibacillus, Lactobacillus, and Limosilactobacillus being characteristic of sour porridge in Bayannur area. Moreover, some LAB genera and Acetobacter were found to have a positive effect on flavor formation in sour porridge.

The Application of Protective Cultures in Cheese: A Review

A number of non-thermal preservation strategies have been adopted from the dairy industry to improve cheese quality and safety. The application of lactic acid bacteria cultures that produce bacteriocins has been extensively studied as a means of bio-preservation. However, the application of purified bacteriocins as a bio-protective agent is limited in cheese. The application of protective cultures is another strategy, and the aim of the current review is to provide an overview of the application of commercial and autochthonous adjunct cultures on the bio-protection of cheese; both public health and spoilage aspects are considered.

Phenotypic, Technological, Safety, and Genomic Profiles of Gamma-Aminobutyric Acid-Producing Lactococcus lactis and Streptococcus thermophilus Strains Isolated from Cow's Milk.

Gamma-aminobutyric acid (GABA)-producing lactic acid bacteria (LAB) can be used as starters in the development of GABA-enriched functional fermented foods. In this work, four GABA-producing strains each of Lactococcus lactis and Streptococcus thermophilus species were isolated from cow's milk, and their phenotypic, technological, and safety profiles determined. Genome analysis provided genetic support for the majority of the analyzed traits, namely, GABA production, growth in milk, and the absence of genes of concern. The operon harboring the glutamate decarboxylase gene (gadB) was chromosomally encoded in all strains and showed the same gene content and gene order as those reported, respectively, for L. lactis and S. thermophilus. In the latter species, the operon was flanked (as in most strains of this species) by complete or truncated copies of insertion sequences (IS), suggesting recent acquisition through horizontal gene transfer. The genomes of three L. lactis and two S. thermophilus strains showed a gene encoding a caseinolytic proteinase (PrtP in L. lactis and PrtS in S. thermophilus). Of these, all but one grew in milk, forming a coagulum of good appearance and an appealing acidic flavor and taste. They also produced GABA in milk supplemented with monosodium glutamate. Two L. lactis strains were identified as belonging to the biovar. diacetylactis, utilized citrate from milk, and produced significant amounts of acetoin. None of the strains showed any noticeable antibiotic resistance, nor did their genomes harbor transferable antibiotic resistance genes or genes involved in toxicity, virulence, or pathogenicity. Altogether these results suggest that all eight strains may be considered candidates for use as starters or components of mixed LAB cultures for the manufacture of GABA-enriched fermented dairy products.

Lactic acid bacteria in some Indian fermented foods and their predictive functional profiles.

Lactic acid bacteria (LAB) were isolated from naturally fermented foods of India, viz., sidra, a dried fish product; kinema, a naturally fermented sticky soybean food; and dahi, a naturally fermented milk product. Five strains of LAB, based on 16S rRNA gene sequence, were identified: Lactococcus lactis FS2 (from sidra), Lc. lactis C2D (dahi), Lc. lactis SP2C4 (kinema), Lactiplantibacillus plantarum DHCU70 (=Lactobacillus plantarum) (from dahi), and Lactiplantibacillus plantarum KP1 (kinema). The PICRUSt2 software, a bioinformatic tool, was applied to infer the raw sequences obtained from LAB strains mapped against KEGG database for predictive functionality. Functional features of LAB strains showed genes associated with metabolism (36.47%), environmental information processing (31.42%), genetic information processing (9.83%), and the unclassified (22.28%). KEGG database also showed abundant genes related to predictive membrane transport (29.25%) and carbohydrate metabolism (11.91%). This study may help in understanding the health-promoting benefits of the culturable LAB strains in fermented foods.

Impact of single and mixed cultures of yeasts and lactic acid bacteria in coffee fermentation and cup quality

AbstractSaccharomyces cerevisiae LBTF 21.3, Pichia manshurica LBTF 21.1, and Leuconostoc lactis LBTF 21.1 were used as single and mixed cultures in coffee fermentations. Fermentations carried out in glass jars with P. manshurica LBTF 21.1/Leuc. lactis LBTF 21.1 showed higher fermentation rates than S. cerevisiae LBTF 21.3/P. manshurica LBTF 21.1 or S. cerevisiae LBTF 21.3/Leuc. lactis LBTF 21.1. The highest cup quality was reached with P. manshurica LBTF 21.1/Leuc. lactis LBTF 21.1 (83.0 points). Full factorial design (22) carried out with P. manshurica LBTF 21.1 revealed that the higher proportion of water added before the fermentation resulted in higher production of acetic acid. A contrary effect of this variable was observed on the production of lactic acid with Leuc. lactis LBTF 21.1. Fermentations conducted in bioreactor evidenced the production of acetaldehyde by P. manshurica LBTF 21.1/Leuc. lactis LBTF 21.1, P. manshurica LBTF 21.1, and Leuc. lactis LBTF 21.1. Additionally, the highest cup quality was reached in fermentations with P. manshurica LBTF 21.1 (82.5 points) followed by Leuc. lactis LBTF 21.1 (81.5 points) and P. manshurica LBTF 21.1/Leuc. lactis LBTF 21.1 (81.0 points). Fermentations of coffee with single and mixed cultures are interesting strategies for the improvement of the sensory quality.