Microbial dynamics and quality characteristics of spontaneously fermented salamis produced by replacing pork fat with avocado pulp.

The aim of this study was to develop a novel and healthier fermented meat product by replacing pork fat with avocado pulp (AVP) during salami production. Experimental salamis were produced under laboratory conditions by substituting pork fat with AVP partially (10-AVP) and totally (20-AVP), while control salamis (CTR) remained AVP-free. The microbial composition of control and experimental salamis was assessed using a combined culture-dependent and -independent approach. Over a 20-days ripening period, lactic acid bacteria, coagulase-negative staphylococci, and yeasts dominated the microbial community, with approximate levels of 9.0, 7.0 and 6.0 log CFU/g, respectively. Illumina technology identified 26 taxonomic groups, with leuconostocs being the predominant group across all trials [constituting 31.26-59.12 % of relative abundance (RA)]. Gas Chromatography-Mass Spectrometry (GC-MS) analysis revealed changes in fatty acid composition and volatile organic compounds due to the substitution of pork fat with AVP. Specifically, monounsaturated fatty acids and terpene compounds increased, while saturated fatty acids and lipid oxidation products decreased. Although AVP influenced the sensory characteristics of the salamis, the highest overall satisfaction ratings were observed for the 10-AVP salamis. Consequently, substituting pork fat with AVP emerges as a viable strategy for producing healthier salamis and diversifying the meat product portfolio.

Selection of adjunct cultures for the ripening of plant cheese analogues.

Fermentation contributes to the taste and odor of plant cheeses. The selection of functional cultures for the fermentation of plant cheeses, however, is in its infancy. This study aimed to select lactic acid bacteria for ripening of soy and lupin cheese analogues. Bacillus velezensis and B. amyloliquefaciens were used for germination of seeds to produce proteolytic enzymes; Lactococcus lactis and Lactiplantibacillus plantarum served as primary acidifying cultures. Levilactobacillus hammesii, Furfurilactobacillus milii, or Lentilactobacillus buchneri were assessed as adjunct cultures for the ripening of plant cheese. Growth of bacilli was inhibited at low pH. Both Lc. lactis and Lp. plantarum were inactived during plant cheese ripening. Cell counts of Lv. hammesii remained stable over 45 d of ripening while Ff. milii and Lt. buchneri grew slowly. Sequencing of full length 16S rRNA genes confirmed that the inocula the plant cheeses accounted for more than 98% of the bacterial communities. HPLC analysis revealed that Lt. buchneri metabolized lactate to acetate and 1,2-propanediol during ripening. Bacilli enhanced proteolysis as measured by quantification of free amino nitrogen, and the release of glutamate. LC-MS/MS analysis quantified kokumi-active dipeptides. The concentrations of γ-Glu-Leu, γ-Glu-Ile, and γ-Glu-Ala, γ-Glu-Cys in unripened cheeses were increased by seed germination but γ-Glu-Phe was degraded. Lt. buchneri but not Lv. hammesii or Ff. milii accumulated γ-Glu-Val, γ-Glu-Ile or γ-Glu-Leu during ripening, indicating strain-specific differences. In conclusion, a consortium of bacilli, acidification cultures and adjunct cultures accumulates taste- and kokumi-active compounds during ripening of plant cheeses.

Probiotic Potential and Application of Indigenous Non-Starter Lactic Acid Bacteria in Ripened Short-Aged Cheese.

There are massive sources of lactic acid bacteria (LAB) in traditional dairy products. Some of these indigenous strains could be novel probiotics with applications in human health and supply the growing needs of the probiotic industry. In this work, were analyzed the probiotic and technological properties of three Lactobacilli strains isolated from traditional Brazilian cheeses. In vitro tests showed that the three strains are safe and have probiotic features. They presented antimicrobial activity against pathogenic bacteria, auto-aggregation values around 60%, high biofilm formation properties, and a survivor of more than 65% to simulated acid conditions and more than 100% to bile salts. The three strains were used as adjunct cultures separately in a pilot-scale production of Prato cheese. After 45 days of ripening, the lactobacilli counts in the cheeses were close to 8 Log CFU/g, and was observed a reduction in the lactococci counts (around -3 Log CFU/g) in a strain-dependent manner. Cheese primary and secondary proteolysis were unaffected by the probiotic candidates during the ripening, and the strains showed no lipolytic effect, as no changes in the fatty acid profile of cheeses were observed. Thus, our findings suggest that the three strains evaluated have probiotic properties and have potential as adjunct non-starter lactic acid bacteria (NSLAB) to improve the quality and functionality of short-aged cheeses.

Mechanistic study of the differences in lactic acid bacteria resistance to freeze- or spray-drying and storage.

Lactobacillus delbrueckii subsp. bulgaricus and Lactiplantibacillus plantarum are two lactic acid bacteria (LAB) widely used in the food industry. The objective of this work was to assess the resistance of these bacteria to freeze- and spray-drying and study the mechanisms involved in their loss of activity. The culturability and acidifying activity were measured to determine the specific acidifying activity, while membrane integrity was studied by flow cytometry. The glass transitions temperature and the water activity of the dried bacterial suspensions were also determined. Fourier transform infrared (FTIR) micro-spectroscopy was used to study the biochemical composition of cells in an aqueous environment. All experiments were performed after freezing, drying and storage at 4, 23 and 37 °C. The results showed that Lb. bulgaricus CFL1 was sensitive to osmotic, mechanical, and thermal stresses, while Lpb. plantarum WCFS1 tolerated better the first two types of stress but was more sensitive to thermal stress. Moreover, FTIR results suggested that the sensitivity of Lb. bulgaricus CFL1 to freeze-drying could be attributed to membrane and cell wall degradation, whereas changes in nucleic acids and proteins would be responsible of heat inactivation of both strains associated with spray-drying. According to the activation energy values (47-85 kJ/mol), the functionality loss during storage is a chemically limited reaction. Still, the physical properties of the glassy matrix played a fundamental role in the rates of loss of activity and showed that a glass transition temperature 40 °C above the storage temperature is needed to reach good preservation during storage. KEY POINTS: • Specific FTIR bands are proposed as markers of osmotic, mechanic and thermal stress • Lb. bulgaricus CFL1 was sensitive to all three stresses, Lpb. plantarum WCFS1 to thermal stress only • Activation energy revealed chemically limited reactions ruled the activity loss in storage.

Lacto-fermented garlic handcrafted in the Lower Silesia Region (Poland): Microbial diversity, morpho-textural traits, and volatile compounds.

The aim of the present study was to provide a first characterization of lacto-fermented garlic manufactured by local small-scale artisanal producers in the Lower Silesia Region (Poland). The lacto-fermented garlic samples showed high nutritional features in terms of antioxidant activity. A total of 86 compounds, belonging to various chemical classes, were identified by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC/MS). Most of these compounds belonged to six main classes, being sulfur compounds, esters and acetates, oxygenated monoterpenes, monoterpene hydrocarbons, and alcohols. Aldehydes, acids, ketones, furans, and phenols were also identified. In the analyzed samples, counts up to 8 log cfu g-1 were observed for lactic acid bacteria. Metataxonomic analysis revealed the presence of Levilactobacillus, Lactiplantibacillus, Latilactobacillus, Secundilactobacillus, Weissella, Leuconostoc, Lactococcus, Pediococcus, and Lacticaseibacillus among the major taxa. These results were confirmed by the isolation and characterization of viable lactic acid bacteria. Indeed, the presence of the closest relatives to Lacticaseibacillus casei group, Pediococcus parvulus, Levilactobacillus brevis, Levilactobacillus parabrevis, and Lactiplantibacillus plantarum group was observed. A good acidification performance in salty garlic-based medium was observed for all the isolates that, between 8 and 15 days of fermentation, reached pH values comprised between 4 and 3.5, depending on the tested species. Of note, 15 out of the 37 lactic acid bacteria isolates (Levilactobacillus parabrevis, Pediococcus parvulus, Lactiplantibacillus plantarum group, and Lacticaseibacillus casei group) showed the presence of the hdcA gene of Gram-positive bacteria encoding for histidine decarboxylase. Furthermore, for 8 out of the 37 isolates the in-vitro exopolysaccharides production was observed. No isolate showed inhibitory activity against the three Listeria innocua strains used as surrogate for Listeria monocytogenes.

Selection of starter lactic acid bacteria capable of forming biofilms on wooden vat prototypes for their future application in traditional Sicilian goat's milk cheese making.

In this study, 327 presumptive lactic acid bacteria (LAB) were isolated from goats' milk acid curds produced at a Sicilian dairy farm with the aim to identify potential starter cultures for traditional cheeses. All isolates were first processed by randomly amplified polymorphic DNA (RAPD)-PCR analysis. This approach identified 63 distinct strains which were evaluated for their acidifying capacity. Only 15 strains specifically stood out for their acidification capacity and were identified through 16S rRNA gene sequencing as Lactococcus lactis (11 strains) Enterococcus faecalis (three strains), and Ligilactobacillus animalis (one strain). Notably, all 15 LAB isolates produced bacteriocin-like inhibitory substances and anti-biofilm compounds, against both planktonic and biofilm forms of Listeria monocytogenes, Salmonella Enteritidis, Escherichia coli, and Staphylococcus aureus, albeit at varying levels. Among these 15 LAB, En. faecalis RGM25 and Lc. lactis RGM55, susceptible to five antibiotics tested, were put in contact with wooden vat prototypes, because all equipment used in traditional cheese production in Sicily are made of wood. Scanning electron microscopy and bacterial plate counts of the wooden vat prototypes showed the development of biofilms at levels of approximately 6.0 log CFU/cm2. Overall, this study contributes to establishing a custom-made LAB starter cultures with bio-preservatives properties for Sicilian cheese productions.

Lactic acid bacteria fermentation improves physicochemical properties, bioactivity, and metabolic profiles of Opuntia ficus-indica fruit juice.

Lactic acid bacteria (LAB) fermentation has been proven to promote human health. The effect of different LAB fermentation on the quality of Opuntia ficus-indica fruit juice (OFIJ) was investigated. OFIJ was an excellent substrate for fermentation, with colony counts of more than 8 log CFU/mL after fermentation. The fermentation altered the acid and sugar contents. Simultaneously, the total phenolic and anthocyanin contents significantly increased. Antioxidant activity enhanced significantly in Lactiplantibacillus plantarum HNU082-fermented OFIJ, primarily in ABTS+ (increased by 16.81%) and DPPH (increased by 23.62%) free radical scavenging ability. Lacticaseibacillus paracasei HNU502-fermented OFIJ showed the most potent inhibition of xanthine oxidase (IC50 = 31.01 ± 3.88 mg TAC/L). Analysis of volatile and non-volatile compounds indicated that fermentation changed the flavor quality and metabolic profiles and caused the most significant modifications in amino acid metabolism. These findings offer valuable information into processing of OFIJ, making it a great choice for functional foods.

Isolation, identification, and characterization of thermophilic lactic acid bacteria isolated from whey of Kars Kashar cheeses.

Kars Kashar cheese is an artisanal pasta-filata type cheese and geographically marked in Eastern Anatolia of Turkey. The aims of this research were to determine for the first time thermophilic lactic acid bacteria (LAB) of Kars Kashar cheese and characterize the technological properties of obtained isolates. In our research, a number of 15 samples of whey were collected from the different villages in Kars. These samples were incubated at 45 °C and used as the source material for isolating thermophilic LAB. A total of 250 colonies were isolated from thermophilic whey, and 217 of them were determined to be presumptive LAB based on their Gram staining and catalase test. A total of 170 isolates were characterized by their phenotypic properties and identified using the MALDI-TOF mass spectrometry method. Phenotypic identification of isolates displayed that Enterococcus and Lactobacillus were the predominant microbiota. According to MALDI-TOF MS identification, 89 isolates were identified as Enterococcus (52.35%), 57 isolates as Lactobacillus (33.53%), 23 isolates as Streptococcus (13.53%), and one isolate as Lactococcus (0.59%). All thermophilic LAB isolates were successfully identified to the species level and it has been observed that MALDI-TOF MS can be successfully used for the identification of selected LAB. The acidification and proteolytic activities of the isolated thermophilic LAB were examined, and the isolates designated for use as starter cultures were also genotypically defined.

Antifungal mechanisms of binary combinations of volatile organic compounds produced by lactic acid bacteria strains against Aspergillusflavus.

Aspergillus flavus（A. flavus）, a common humic fungus known for its ability to infect agricultural products, served as the subject of investigation in this study. The primary objective was to assess the antifungal efficacy and underlying mechanisms of binary combinations of five volatile organic compounds (VOCs) produced by lactic acid bacteria, specifically in their inhibition of A. flavus. This assessment was conducted through a comprehensive analysis, involving biochemical characterization and transcriptomic scrutiny. The results showed that VOCs induce notable morphological abnormalities in A. flavus conidia and hyphae. Furthermore, they disrupt the integrity of the fungal cell membrane and cell wall, resulting in the leakage of intracellular contents and an increase in extracellular electrical conductivity. In terms of cellular components, VOC exposure led to an elevation in malondialdehyde content while concurrently inhibiting the levels of total lipids, ergosterol, soluble proteins, and reducing sugars. Additionally, the impact of VOCs on A. flavus energy metabolism was evident, with significant inhibition observed in the activities of key enzymes, such as Na+/K+-ATPase, malate dehydrogenase, succinate dehydrogenase, and chitinase. And they were able to inhibit aflatoxin B1 synthesis. The transcriptomic analysis offered further insights, highlighting that differentially expressed genes (DEGs) were predominantly associated with membrane functionality and enriched in pathways about carbohydrate and amino acid metabolism. Notably, DEGs linked to cellular components and energy-related mechanisms exhibited down-regulation, thereby corroborating the findings from the biochemical analyses. In summary, these results elucidate the principal antifungal mechanisms of VOCs, which encompass the disruption of cell membrane integrity and interference with carbohydrate and amino acid metabolism in A. flavus.

Lactic acid fermented microalgae and cyanobacteria as a new source of lipid reducing compounds: assessment through zebrafish Nile red fat metabolism assay and untargeted metabolomics.

Obesity is one of the most important threats to human health. Besides existing pharmacological or clinical interventions, novel effective and largely available solutions are still necessary. Among diverse natural resources, microalgae are well known for their complexity in the production of novel secondary metabolites. At the same time, lactic acid bacteria (LAB) are known for their capacity to metabolize, through fermentation, different matrices, and consequently to modify or produce new compounds with potential bioactivity. This work aimed to study the production of fermented microalgae and cyanobacteria, and to analyse their extracts in the zebrafish Nile red fat metabolism assay. Three microalgal species (Chlorella vulgaris, Chlorococcum sp. and Arthrospira platensis) were fermented with seven strains of LAB from 4 species (Lacticaseibacillus rhamnosus, Lacticaseibacillus casei, Lactobacillus delbrueckii bulgaricus and Lacticaseibacillus paracasei), derived from the UPCCO - University of Parma Culture Collection, Parma, Italy). All the selected strains were able to ferment the selected species of microalgae, and the most suitable substrate for LAB growth was Arthrospira platensis. Extracts from fermented Chlorella vulgaris and Chlorococcum sp. reduced significantly the neutral lipid reservoirs, which was not observed without fermentations. The strongest lipid reducing effect was obtained with Arthrospira platensis fermented with Lactobacillus delbrueckii bulgaricus 1932. Untargeted metabolomics identified some compound families, which could be related to the observed bioactivity, namely fatty acids, fatty amides, triterpene saponins, chlorophyll derivatives and purine nucleotides. This work opens up the possibility of developing novel functional foods or food supplements based on microalgae, since lactic acid fermentation enhanced the production of bioactive compounds with lipid reducing activities.

Phenotypic and genotypic characterization of antimicrobial resistances reveals the effect of the production chain in reducing resistant lactic acid bacteria in an artisanal raw ewe milk PDO cheese.

Antimicrobial resistance (AMR) is a significant public health threat, with the food production chain, and, specifically, fermented products, as a potential vehicle for dissemination. However, information about dairy products, especially raw ewe milk cheeses, is limited. The present study analysed, for the first time, the occurrence of AMRs related to lactic acid bacteria (LAB) along a raw ewe milk cheese production chain for the most common antimicrobial agents used on farms (dihydrostreptomycin, benzylpenicillin, amoxicillin and polymyxin B). More than 200 LAB isolates were obtained and identified by Sanger sequencing (V1-V3 16S rRNA regions); these isolates included 8 LAB genera and 21 species. Significant differences in LAB composition were observed throughout the production chain (P ≤ 0.001), with Enterococcus (e.g., E. hirae and E. faecalis) and Bacillus (e.g., B. thuringiensis and B. cereus) predominating in ovine faeces and raw ewe milk, respectively, along with Lactococcus (L. lactis) in whey and fresh cheeses, while Lactobacillus and Lacticaseibacillus species (e.g., Lactobacillus sp. and L. paracasei) prevailed in ripened cheeses. Phenotypically, by broth microdilution, Lactococcus, Enterococcus and Bacillus species presented the greatest resistance rates (on average, 78.2 %, 56.8 % and 53.4 %, respectively), specifically against polymyxin B, and were more susceptible to dihydrostreptomycin. Conversely, Lacticaseibacillus and Lactobacillus were more susceptible to all antimicrobials tested (31.4 % and 39.1 %, respectively). Thus, resistance patterns and multidrug resistance were reduced along the production chain (P ≤ 0.05). Genotypically, through HT-qPCR, 31 antimicrobial resistance genes (ARGs) and 6 mobile genetic elements (MGEs) were detected, predominating Str, StrB and aadA-01, related to aminoglycoside resistance, and the transposons tnpA-02 and tnpA-01. In general, a significant reduction in ARGs and MGEs abundances was also observed throughout the production chain (P ≤ 0.001). The current findings indicate that LAB dynamics throughout the raw ewe milk cheese production chain facilitated a reduction in AMRs, which has not been reported to date.

Novel insight into the formation and improvement mechanism of physical property in fermented tilapia sausage by cooperative fermentation of newly isolated lactic acid bacteria based on microbial contribution.

Single starter can hardly elevate the gel property of fermented freshwater fish sausage. In this work, in order to improve the physical properties of tilapia sausage, two newly isolated strains of lactic acid bacteria (LAB), Latilactobacillus sakei and Pediococcus acidilactici were used for cooperative fermentation of tilapia sausage, followed by the revelation of their formation mechanisms during cooperative fermentation and their improvement mechanisms after comparison with natural fermentation. Both strains, especially L. sakei possessed good growth, acidification ability, and salt tolerance. The gel strength, hardness, springiness, chewiness, whiteness, acidification, and total plate count significantly elevated during cooperative fermentation with starters. Pediococcus, Acinetobacter, and Macrococcus were abundant before fermentation, while Latilactobacillus quickly occupied the dominant position after fermentation for 18-45 h with the relative abundance over 51.5 %. The influence of each genus on the physical properties was calculated through the time-dimension and group-dimension correlation networks. The results suggested that the increase of Latilactobacillus due to the good growth and metabolism of L. sakei contributed the most to the formation and improvement of gel strength, texture properties, color, acidification, and food safety of tilapia sausage after cooperative fermentation. This study provides a novel analysis method to quantitatively evaluate the microbial contribution on the changes of various properties. The cooperative fermentation of LAB can be used for tilapia sausage fermentation to improve its physical properties.

Study protocol: The role of milk matrix lipids in programming the immunoreactivity of proteins derived from lactic acid bacteria.

Food allergy is widely recognized as a significant health issue, having escalated into a global epidemic, subsequently giving rise to the development of numerous additional complications. Currently, the sole efficient method to curb the progression of allergy is through the implementation of an elimination diet. The increasing number of newly identified allergens makes it harder to completely remove or avoid them effectively. The immunoreactivity of proteins of bacterial origin remains an unexplored topic. Despite the substantial consumption of microbial proteins in our diets, the immunologic mechanisms they might induce require thorough validation. This stands as the primary objective of this study. The primary objective of this study was to evaluate the effects of bacterial proteins on the intestinal barrier and immune system parameters during hypersensitivity induction in both developing and mature organisms. The secondary objective was to evaluate the role of lipids in the immunoreactivity programming of these bacterial proteins. Notably, in this complex, comprehensively designed in vitro, in vivo, and ex vivo trial, the immunoreactivity of various bacterial proteins will be examined. In summary, the proposed study intends to address the knowledge gaps regarding the effects of Lactobacillus microbial proteins on inflammation, apoptosis, autophagy, and intestinal barrier integrity in a single study.

Variation of volatile compounds and sensory profile for Protaetia brevitarsis larvae fermented with lactic acid bacteria and yeast.

This study aimed to investigate the correlation between the composition of volatile compounds, consumer acceptance, and drivers of (dis)liking of Protaetia brevitarsis larvae fermented using lactic acid bacteria and yeast. Volatile compounds were analyzed using HS-SPME-Arrow-GC-MS, and a sensory evaluation was conducted with 72 consumers. A total of 113 volatile compounds were detected, and principal component analysis indicated that the samples could be divided into three groups. The calculated relative odor activity values (ROAV) revealed the presence of 27 compounds (ROAV >1). Volatile compounds with high ROAV were predominantly found during yeast fermentation. The sensory evaluation results indicated a strong correlation between low levels of off-odor intensity and high odor liking, emphasizing that odor profile had a more direct association with consumer acceptance than odor intensity. These findings suggest that yeast fermentation using volatile compounds, which positively influences consumer acceptance, is appropriate for Protaetia brevitarsis larvae.

Investigation on the exopolysaccharide production from blueberry juice fermented with lactic acid bacteria: Optimization, fermentation characteristics and Vis-NIR spectral model.

The exopolysaccharide production from blueberry juice fermented were investigated. The highest exopolysaccharide yield of 2.2 ± 0.1 g/L (increase by 32.5 %) was reached under the conditions of temperature 26.5 °C, pH 5.5, inoculated quantity 5.4 %, and glucose addition 9.1 % using the artificial neural network and genetic algorithm. Under the optimal conditions, the viable cell counts and total acids were increased by 2.0 log CFU/mL and 1.6 times, respectively, while the content of phenolics and anthocyanin was decreased by 9.26 % and 7.86 %, respectively. The changes of these components affected the exopolysaccharide biosynthesis. The absorption bands of -OH and -CH associated with the main functional groups of exopolysaccharide were detected by Visible near-infrared spectroscopy. The prediction model based on spectrum results was constructed. Competitive adaptive reweighted sampling and the random forest were used to enhance the model's prediction performance with the value of RC = 0.936 and RP = 0.835, indicating a good predictability of exopolysaccharides content during fermentation.

Characterization of differences in physicochemical properties, volatile organic compounds and non-volatile metabolites of prune wine by inoculation of different lactic acid bacteria during malolactic fermentation.

To investigate the effects of inoculating with three strains of lactic acid bacteria on prune wine quality during malolactic fermentation, this study determined its antioxidant activity, phenolic compounds, organic acids, and volatile/non-volatile metabolites. The results showed that inoculation with Lactobacillus paracasei SMN-LBK improved the antioxidant activity and phenolic compounds of prune wine. 73 VOCs were detected in prune wine by HS-SPME-GC-MS, and VOC content increased by 4.3% and 9.1% in MLFS and MLFB, respectively. Lactobacillus delbrueckii subsp. Bulgaricus showed better potential for winemaking, and citral and 5-nonanol, were detected in the MLF samples. 39 shared differential metabolites were screened and their metabolic pathways were investigated based on nontargeted metabolomics. Differences in amino acid and flavonoid content between strains reflected their specificity in flavonoid biosynthesis and amino acid biosynthesis. These findings will provide useful information for the biochemical study and processing of prune wine.

A New Culture Medium Rich in Phenols Used for Screening Bitter Degrading Strains of Lactic Acid Bacteria to Employ in Table Olive Production.

The olive oil industry recently introduced a novel multi-phase decanter with the "Leopard DMF" series, which gives a by-product called pâté, made up of pulp and olive wastewater with a high content of phenolic substances and without pits. This study aims to create a new culture medium, the Olive Juice Broth (OJB), from DMF pâté, and apply it to select bacteria strains able to survive and degrade the bitter substances normally present in the olive fruit. Thirty-five different bacterial strains of Lactiplantibacillus plantarum from the CREA-IT.PE Collection of Microorganisms were tested. Seven strains characterized by ≥50% growth in OJB (B31, B137, B28, B39, B124, B130, and B51) showed a degradation of the total phenolic content of OJB ≥ 30%. From this set, L. plantarum B51 strain was selected as a starter for table olive production vs. spontaneous fermentation. The selected inoculant effectively reduced the debittering time compared to spontaneous fermentation. Hydroxytyrosol, derived from oleuropein and verbascoside degradation, and tyrosol, derived from ligstroside degradation, were produced faster than during spontaneous fermentation. The OJB medium is confirmed to be useful in selecting bacterial strains resistant to the complex phenolic environment of the olive fruit.

Antifungal mechanisms investigation of lactic acid bacteria against Aspergillus flavus: through combining microbial metabolomics and co-culture system.

AIMS: To develop antifungal lactic acid bacteria (LAB) and investigate their antifungal mechanisms against Aspergillus flavus in aflatoxin (AF) production. METHODS AND RESULTS: We isolated 179 LABs from cereal-based fermentation starters and investigated their antifungal mechanism against A. flavus through liquid chromatography-mass spectrometry and co-culture analysis techniques. Of the 179 isolates, antifungal activity was identified in Pediococcus pentosaceus, Lactobacillus crustorum, and Weissella paramesenteroides. These LABs reduced AF concentration by (i) inhibiting mycelial growth, (ii) binding AF to the cell wall, and (iii) producing antifungal compounds. Species-specific activities were also observed, with P. pentosaceus inhibiting AF production and W. paramesenteroides showing AF B1 binding activity. In addition, crucial extracellular metabolites for selecting antifungal LAB were involved in the 2',3'-cAMP-adenosine and nucleoside pathways. CONCLUSIONS: This study demonstrates that P. pentosaceus, L. crustorum, and W. paramesenteroides are key LAB strains with distinct antifungal mechanisms against A. flavus, suggesting their potential as biological agents to reduce AF in food materials.

The predominant lactic acid bacteria and yeasts involved in the spontaneous fermentation of millet during the production of the traditional porridge Hausa koko in Ghana.

Spontaneous fermentation of cereals like millet involves a diverse population of microbes from various sources, including raw materials, processing equipment, fermenting receptacles, and the environment. Here, we present data on the predominant microbial species and their succession at each stage of the Hausa koko production process from five regions of Ghana. The isolates were enumerated using selective media, purified, and phenotypically characterised. The LAB isolates were further characterised by 16S rRNA Sanger sequencing, typed using (GTG)5 repetitive-PCR, and whole genome sequencing, while 28S rRNA Sanger sequencing was performed for yeast identification. The pH of the millet grains ranged from mean values of 6.02-6.53 to 3.51-3.99 in the final product, depending on the processors. The mean LAB and yeast counts increased during fermentation then fell to final counts of log 2.77-3.95 CFU/g for LAB and log 2.10-2.98 CFU/g for yeast in Hausa koko samples. At the various processing stages, the counts of LAB and yeast revealed significant variations (p < 0.0001). The species of LAB identified in this study were Limosilactobacillus pontis, Pediococcus acidilactici, Limosilactobacillus fermentum, Limosilactobacillus reuteri, Pediococcus pentosaceus, Lacticaseibacillus paracasei, Lactiplantibacillus plantarum, Schleiferilactobacillus harbinensis, and Weissella confusa. The yeasts were Saccharomyces cf. cerevisiae/paradoxus, Saccharomyces cerevisiae, Pichia kudriavzevii, Clavispora lusitaniae and Candida tropicalis. The identification and sequencing of these novel isolates and how they change during the fermentation process will pave the way for future controlled fermentation, safer starter cultures, and identifying optimal stages for starter culture addition or nutritional interventions. These LAB and yeast species are linked to many indigenous African fermented foods, potentially acting as probiotics in some cases. This result serves as the basis for further studies into the technological and probiotic potential of these Hausa koko microorganisms.

Identification of microorganisms in wet coffee fermentation Coffea arabica Var Catimor and Castillo in Jardín, Antioquia-Colombia, using culture-dependent methods / Identificación de microorganismos en fermentación húmeda de café Coffea arabica Var Catimor y Castillo en Jardín, Antioquia-Colombia, usando métodos cultivo-dependientes

Background: Mild Colombian coffees are recognized worldwide for their high-quality coffee cup. However, there have been some failures in post-harvest practices, such as coffee grain fermentation. These failures could occasionally lead to defects and inconsistencies in quality products and economic losses for coffee farmers. In Colombia, one of the fermentation methods most used by coffee growers is wet fermentation, conducted by submerging the de-pulped coffee beans for enough time in water tanks to remove the mucilage. Objectives: We evaluated the effect of the water (g)/de-pulped coffee (g) ratio (I: 0/25, II: 10/25, III: 20/25) and final fermentation time (24, 48, and 72 hours) on the total number of microbial groups. We also identified microorganisms of interest as starter cultures. Methods: We used a completely randomized experimental design with two factors; the effect of the water (g)/de-pulped coffee (g) ratio (I: 0/25, II: 10/25, III: 20/25) and final fermentation time (24, 48, and 72 hours), for 9 treatments with two replicates. During the coffee fermentation (1,950 g), the pH and °Brix were monitored. Total counts of different microbial groups (mesophiles, coliforms, lactic-acid bacteria, acetic-acid bacteria, and yeasts) were performed. Various isolates of microorganisms of interest as starter cultures (lactic-acid bacteria and yeasts) were identified using molecular sequencing techniques. Results: 21 lactic-acid bacteria (LAB) isolates and 22 yeasts were obtained from the different mini-batch fermentation systems. The most abundant lactic-acid bacteria species found were Lactiplantibacillus plantarum (46%) and Levilactobacillus brevis (31%). Pichia kluivery (39%) and Torulaspora delbrueckii (22%) were the most abundant yeast species. Conclusion The studied factors did not have effect over the microorganism's development. The identified bacterial and yeasts species have potential as starter cultures for better-quality coffees and in fermentation-related applications.

Antecedentes: Los cafés suaves lavados colombianos son reconocidos a nivel mundial por su buena puntuación sensorial; sin embargo, se han detectado fallas en las prácticas de postcosecha, como lo es la fermentación de los granos de café. Dichas fallas pueden causar defectos y carecer de consistencia en la calidad del producto, ocasionando pérdidas económicas para los caficultores. En Colombia, uno de los métodos más usados por los caficultores es la fermentación húmeda, la cual consiste en sumergir los granos de café despulpado en tanques con agua por un período de tiempo que permita la remoción del mucílago. Objetivos: La presente investigación evaluó la incidencia que tienen la proporción agua/granos despulpados de café (I: 0/25, II: 10/25, III: 20/25) y el tiempo final de fermentación (24, 48 y 72 horas) en el recuento final de grupos microbianos. Por otra parte, se identificaron taxonómicamente microorganismos de interés para su uso como cultivos iniciadores. Métodos: Mini-lotes consistieron en café despulpado (1950 g) puesto en recipientes de plástico abiertos y sumergidos en agua. Se aplicó un diseño experimental completamente aleatorizado de dos factores (proporción agua/ granos de café despulpado y tiempo) a tres niveles, para un total de nueve tratamientos con dos replicas. Durante las fermentaciones de café (1,950 g), el pH y los grados ºBrix, fueron monitoreados. Se realizaron los recuentos totales de los diferentes grupos microbianos: mesófilos, coliformes, bacterias ácido-lácticas, bacterias ácido-acéticas y levaduras. Se identificaron molecularmente diferentes aislados con potencial para ser usados como cultivos iniciadores (bacterias ácido-lácticas y levaduras). Resultados: Los resultados obtenidos mostraron que no hubo diferencia estádisticamente significativa entre los tratamientos aplicados y el recuento final de microorganismos. Un total de 21 aislados de bacterias ácido-lácticas (BAL) y 22 levaduras lograron obtenerse a partir de los diferentes sistemas de fermentación en mini-lote. Las especies de bacterias ácido-lácticas con mayor porcentaje acorde a su identificación taxonómica, corresponden a Lactiplantibacillus plantarum (46%), Levilactobacillus brevis (31%). Las especies de levaduras con mayor porcentaje acorde a su identificación taxonómica corresponden a Pichia kluivery (39%) y Torulaspora delbrueckii (22%). Conclusión Los factores estudiados no afectaron el crecimiento de ninguno de los grupos microbianos presentes en la fermentacion del café. Las especies de microorganismos identificados tienen potencial para se usados como cultivos starter o en aplicaciones dentro de las ciencias de fermentación.