Lactobacillus amylovorus DSM 19280 as a novel food-grade antifungal agent for bakery products

A Snapshot, Using a Multi-Omic Approach, of the Metabolic Cross-Talk and the Dynamics of the Resident Microbiota in Ripening Cheese Inoculated with Listeria innocua

Raw milk cheeses harbor complex microbial communities. Some of these microorganisms are technologically essential, but undesirable microorganisms can also be present. While most of the microbial dynamics and cross-talking studies involving interaction between food-derived bacteria have been carried out on agar plates in laboratory-controlled conditions, the present study evaluated the modulation of the resident microbiota and the changes of metabolite production directly in ripening raw milk cheese inoculated with Listeria innocua strains. Using a proxy of the pathogenic Listeria monocytogenes, we aimed to establish the key microbiota players and chemical signals that characterize Latteria raw milk cheese over 60 days of ripening time. The microbiota of both the control and Listeria-inoculated cheeses was analyzed using 16S rRNA targeted amplicon sequencing, while direct analysis in real time mass spectrometry (DART-HRMS) was applied to investigate the differences in the metabolic profiles of the cheeses. The diversity analysis showed the same microbial diversity trend in both the control cheese and the inoculated cheese, while the taxonomic analysis highlighted the most representative genera of bacteria in both the control and inoculated cheese: Lactobacillus and Streptococcus. On the other hand, the metabolic fingerprints revealed that the complex interactions between resident microbiota and L. innocua were governed by continuously changing chemical signals. Changes in the amounts of small organic acids, hydroxyl fatty acids, and antimicrobial compounds, including pyroglutamic acid, hydroxy-isocaproic acid, malic acid, phenyllactic acid, and lactic acid, were observed over time in the L. innocua-inoculated cheese. In cheese that was inoculated with L. innocua, Streptococcus was significantly correlated with the volatile compounds carboxylbenzaldheyde and cyclohexanecarboxylic acid, while Lactobacillus was positively correlated with some volatile and flavor compounds (cyclohexanecarboxylic acid, pyroxidal acid, aminobenzoic acid, and vanillic acid). Therefore, we determined the metabolic markers that characterize a raw milk cheese inoculated with L. innocua, the changes in these markers with the ripening time, and the positive correlation of flavor and volatile compounds with the resident microbiota. This multi-omics approach could suggest innovative food safety strategies based on the enhanced management of undesirable microorganisms by means of strain selection in raw matrices and the addition of specific antimicrobial metabolites to prevent the growth of undesirable microorganisms.

Improving the microbial and physicochemical shelf life of yufka paste using Lactobacillus plantarum and calcium propionate

Considering the importance of reducing the use of chemical preservatives in food and the increasing attention of consumers to consume food products with minimal additives, the main goal of this research was to study the effect of use of chemical (calcium propionate) and biological (Lactobacillus plantarum) preservatives on increasing shelf life of yufka paste considering its physicochemical and microbial characteristics. For this purpose, three samples of yufka paste were prepared by adding concentrations of 103, 105, and 107 cfu/mL of L. plantarum individually and three samples of paste were prepared by adding the same amount of bacteria in combination with 0.3% calcium propionate and these samples were compared with the control sample (without preservative) and the sample only containing 0.3% calcium propionate. The obtained results showed that different treatments and time had a significant effect on physicochemical properties including pH, moisture, and protein of yufka paste (p < .05). The results of the survival of L. plantarum showed that with increasing time, the survival rate of bacteria increased (p < .05). The pH of the samples showed that the L. plantarum has a significant effect on controlling the chemical quality of yufka during storage. The count of mold and yeast in the combined use of L. plantarum and 0.3% propionate was lower than the single use of propionate chemical preservative, which indicated the very good effect of the green preservative in controlling the moldy spoilage of yufka. Low concentrations of bacteria showed better antimold results than treatments containing bacteria and propionate in a combined form, propionate or control treatment.

Reuterin, Phenyllactic Acid, and Exopolysaccharides as Main Antifungal Molecules Produced by Lactic Acid Bacteria: A Scoping Review

The primary goal of this scoping review is to collect, analyze, and critically describe information regarding the role of the main compounds (reuterin, phenyllactic acid, and exopolysaccharides) produced by LAB that possess antifungal properties and provide some suggestions for further research. The use of lactic acid bacteria (LAB) to mitigate spoilage and extend the shelf life of foodstuffs has a long history. Recently, there has been a growing interest in the unique properties of these additions to the foodstuffs in which they are applied. In recent studies regarding biopreservation, significant attention has been given to the role of these microorganisms and their metabolites. This fascinating recent discipline aims not only to replace traditional preservation systems, but also to improve the overall quality of the final product. The biologically active by-products produced by lactic acid bacteria are synthesized under certain conditions (time, temperature, aerobiosis, acidity, water activity, etc.), which can be enacted through one of the oldest approaches to food processing: fermentation (commonly used in the dairy and bakery sectors). This study also delves into the biosynthetic pathways through which they are synthesized, with a particular emphasis on what is known about the mechanisms of action against molds in relation to the type of food.

Fusarium biocontrol: antagonism and mycotoxin elimination by lactic acid bacteria

Mycotoxins produced by Fusarium species are secondary metabolites with low molecular weight formed by filamentous fungi generally resistant to different environmental factors and, therefore, undergo slow degradation. Contamination by Fusarium mycotoxins in cereals and millets is the foremost quality challenge the food and feed industry faces across the globe. Several types of chemical preservatives are employed in the mitigation process of these mycotoxins, and they help in long-term storage; however, chemical preservatives can be used only to some extent, so the complete elimination of toxins from foods is still a herculean task. The growing demand for green-labeled food drives to evade the use of chemicals in the production processes is getting much demand. Thus, the biocontrol of food toxins is important in the developing food sector. Fusarium mycotoxins are world-spread contaminants naturally occurring in commodities, food, and feed. The major mycotoxins Fusarium species produce are deoxynivalenol, fumonisins, zearalenone, and T2/HT2 toxins. Lactic acid bacteria (LAB), generally regarded as safe (GRAS), is a well-explored bacterial community in food preparations and preservation for ages. Recent research suggests that LAB are the best choice for extenuating Fusarium mycotoxins. Apart from Fusarium mycotoxins, this review focuses on the latest studies on the mechanisms of how LAB effectively detoxify and remove these mycotoxins through their various bioactive molecules and background information of these molecules.

Antifungal Activity of Cell-Free Filtrate of Probiotic Bacteria Lactobacillus rhamnosus ATCC-7469 against Fungal Strains Isolated from a Historical Manuscript

Herein, twelve fungal strains were isolated from a deteriorated historical manuscript dated back to the 18th century. The obtained fungal strains were identified, using the traditional method and ITS sequence analysis, as Cladosporium herbarum (two strains), Aspergillus fumigatus (five strains), A. ustus (one strain), A. flavus (two strains), A. niger (one strain), and Penicillium chrysogenum (one strain). The ability of these fungal strains to degrade the main components of the paper was investigated by their activity to secrete extracellular enzymes including cellulase, amylase, gelatinase, and pectinase. The cell-free filtrate (CFF) ability of the probiotic bacterial strain Lactobacillus rhamnosus ATCC-7469 to inhibit fungal growth was investigated. The metabolic profile of CFF was detected by GC-MS analysis, which confirmed the low and high molecular weight of various active chemical compounds. The safe dose to be used for the biocontrol of fungal growth was selected by investigating the biocompatibility of CFF and two normal cell lines, Wi38 (normal lung tissue) and HFB4 (normal human skin melanocyte). Data showed that the CFF has a cytotoxic effect against the two normal cell lines at high concentrations, with IC₅₀ values of 525.2 ± 9.8 and 329.1 ± 4.2 µg mL^-1 for Wi38 and HFB4, respectively. The antifungal activity showed that the CFF has promising activity against all fungal strains in a concentration-dependent manner. The highest antifungal activity (100%) was recorded for a concentration of 300 µg mL^-1 with a zone of inhibition (ZOI) in the ranges of 21.3 ± 0.6 to 17.7 ± 0.5 mm. At a concentration of 100 µg mL^-1, the activity of CFF remained effective against all fungal strains (100%), but its effectiveness decreased to only inhibit the growth of eight strains (66%) out of the total at 50 µg mL^-1. In general, probiotic bacterial strains containing CFF are safe and can be considered as a potential option for inhibiting the growth of various fungal strains. It is recommended that they be used in the preservation of degraded historical papers.

From Waste to Taste: Application of Fermented Spent Rootlet Ingredients in a Bread System

The process of upcycling and incorporating food by-products into food systems as functional ingredients has become a central focus of research. Barley rootlets (BR) are a by-product of the malting and brewing industries that can be valorised using lactic acid bacteria fermentation. This research investigates the effects of the inclusion of unfermented (BR-UnF), heat-sterilised (BR-Ster), and five fermented BR ingredients (using Weissella cibaria MG1 (BR-MG1), Leuconostoc citreum TR116 (BR-TR116), Lactiplantibacillus plantarum FST1.7 (BR-FST1.7), Lactobacillus amylovorus FST2.11 (BR-FST2.11), and Limosilactobacillus reuteri R29 (BR-R29) in bread. The antifungal compounds in BR ingredients and the impact of BR on dough rheology, gluten development, and dough mixing properties were analysed. Additionally, their effects on the techno-functional characteristics, in vitro starch digestibility, and sensory quality of bread were determined. BR-UnF showed dough viscoelastic properties and bread quality comparable to the baker's flour (BF). BR-MG1 inclusion ameliorated bread specific volume and reduced crumb hardness. Breads containing BR-TR116 had comparable bread quality to BF, while the inclusion of BR-R29 substantially slowed microbial spoilage. Formulations containing BR-FST2.11 and BR-FST1.7 significantly reduced the amounts of sugar released from breads during a simulated digestion and resulted in a sourdough-like flavour profile. This study highlights how BR fermentation can be tailored to achieve desired bread characteristics.

Antifungal activity of lactic acid bacteria and their application in food biopreservation

Lactic acid bacteria (LAB) are ubiquitous bacteria associated with spontaneous lactic fermentation of vegetables, dairy and meat products. They are generally recognized as safe (GRAS), and they are involved in transformation of probiotic lacto-fermented foods, highly desired for their nutraceutical properties. The antifungal activity is one of the exciting properties of LAB, because of its possible application in food bio-preservation, as alternative to chemical preservatives. Many recent research works have been developed on antifungal activity of LAB, and they demonstrate their capacity to produce various antifungal compounds, (i.e. organic acids, PLA, proteinaceous compounds, peptides, cyclic dipeptides, fatty acids, and other compounds), of different properties (hydrophilic, hydrophobic and amphiphilic). The effectiveness of LAB in controlling spoilage and pathogenic fungi, demonstrated in different agricultural and food products, can be due to the synergistic effect between their antifungal compounds of different properties; where the amphiphilic-compounds allow the contact between the target microbial cell (hydrophilic compartment) and antifungal hydrophobic-compounds. Further studies on the interaction between compounds of these three properties are to de be developed, in order to highlight more their mechanism of action, and make LAB more profitable in improving shelf life and nutraceutical properties of foods.

The impact of incorporating Lactobacillus acidophilus bacteriocin with inulin and FOS on yogurt quality

The current study aimed to figure out the effect of using a combination of 2% inulin, and 2% Fructo-oligosaccharides (FOS) with Lactobacillus acidophilus and their bacteriocin on some yogurt properties such as coagulation time, extending the shelf life of set yogurt and its microbiological quality, also the acceptance by consumers. The results indicated that coagulation time increased by 22.75% in yogurts prepared with Lactobacillus acidophilus and their bacteriocins compared to the control, and titratable acidity increased gradually in all treatments during storage. Hence control acidity (%) increased from 0.84 ± 0.02^A at zero time to 1.23 ± 0.03^A after 14 days of cold storage, while treatment (T4) was 0.72 ± 0.01^C at zero time and reached 1.20 ± 0.5^A after 39 days at the same conditions. The sensory properties showed the superiority of inulin, FOS, and Lactobacillus acidophilus bacteriocin groups. Lactobacillus bulgaricus, Streptococcus thermophiles, and Lactobacillus acidophilus count increased in the treatments compared to the control group, with an extended shelf life to 39 days of storage in the medicines containing lactobacillus acidophilus bacteriocin. Coliforms, Moulds, and yeasts did not detect in the treatments comprising 2% inulin, 2% FOS, and lactobacillus acidophilus bacteriocin for 39 days of refrigerated storage. This study proved that 2% inulin, 2% FOS, and Lactobacillus acidophilus bacteriocin fortification extended the shelf life by more than 5 weeks.

Lactic Acid Bacteria in Raw-Milk Cheeses: From Starter Cultures to Probiotic Functions

Traditional cheeses produced from raw milk exhibit a complex microbiota, characterized by a sequence of different microorganisms from milk coagulation and throughout maturation. Lactic acid bacteria (LAB) play an essential role in traditional cheese making, either as starter cultures that cause the rapid acidification of milk or as secondary microbiota that play an important role during cheese ripening. The enzymes produced by such dynamic LAB communities in raw milk are crucial, since they support proteolysis and lipolysis as chief drivers of flavor and texture of cheese. Recently, several LAB species have been characterized and used as probiotics that successfully promote human health. This review highlights the latest trends encompassing LAB acting in traditional raw milk cheeses (from cow, sheep, and goat milk), and their potential as probiotics and producers of bioactive compounds with health-promoting effects.

Application of Lactic Acid Bacteria (LAB) in Sustainable Agriculture: Advantages and Limitations

Lactic acid bacteria (LAB) are significant groups of probiotic organisms in fermented food and are generally considered safe. LAB regulate soil organic matter and the biochemical cycle, detoxify hazardous chemicals, and enhance plant health. They are found in decomposing plants, traditional fermented milk products, and normal human gastrointestinal and vaginal flora. Exploring LAB identified in unknown niches may lead to isolating unique species. However, their classification is quite complex, and they are adapted to high sugar concentrations and acidic environments. LAB strains are considered promising candidates for sustainable agriculture, and they promote soil health and fertility. Therefore, they have received much attention regarding sustainable agriculture. LAB metabolites promote plant growth and stimulate shoot and root growth. As fertilizers, LAB can promote biodegradation, accelerate the soil organic content, and produce organic acid and bacteriocin metabolites. However, LAB show an antagonistic effect against phytopathogens, inhibiting fungal and bacterial populations in the rhizosphere and phyllosphere. Several studies have proposed the LAB bioremediation efficiency and detoxification of heavy metals and mycotoxins. However, LAB genetic manipulation and metabolic engineered tools provide efficient cell factories tailor-made to produce beneficial industrial and agro-products. This review discusses lactic acid bacteria advantages and limitations in sustainable agricultural development.

Comparison Study of Nontreated and Fermented Wheat Varieties 'Ada', 'Sarta', and New Breed Blue and Purple Wheat Lines Wholemeal Flour

The aim of this study was to analyze and compare the acidity, microbiological, and chromaticity parameters; fatty acid (FA) and volatile compound (VC) profiles; and biogenic amine (BA), macro- and microelement, and mycotoxin concentrations in nontreated ‘Ada’, ‘Sarta’, and new breed blue (DS8472-5) and purple (DS8526-2) wheat lines wholemeal (WW) with those fermented with lactic acid bacteria (LAB) possessing antimicrobial/antifungal properties, isolated from spontaneous sourdough: Pediococcus acidilactici-LUHS29, Liquorilactobacillus uvarum-LUHS245, Lactiplantibacillus plantarum-LUHS122). All the fermented WW showed >8.0 log10 CFU/g of LAB count, and the type of LAB was a significant factor in the WW acidity parameters. Phenylethylamine was the predominant BA in WW, and the wheat variety (WV), the type of LAB, and their interaction were significant factors on the BA formation. Despite the fact that some differences in trace element concentrations in WW were obtained, in most of the cases fermentation was not a significant factor in their content. The main FAs in WW were palmitic acid, all-cis,trans-octadecenoic acid, and linoleic acid. Fermented WW showed a more diverse VC profile; however, the influence of fermentation on deoxynivalenol in WW was varied. Finally, further studies are needed to indicate the technological parameters that would be the most effective for each WV, including the lowest BA formation and mycotoxin degradation.

Antifungal Mechanisms and Application of Lactic Acid Bacteria in Bakery Products: A Review

Bakery products are nutritious, but they are susceptible to fungal contamination, which leads to a decline in quality and safety. Chemical preservatives are often used to extend the shelf-life of bakery products, but long-term consumption of these preservatives may increase the risk of chronic diseases. Consumers increasingly demand food with fewer chemical preservatives. The application of lactic acid bacteria (LAB) as a novel biological preservative not only prolongs the shelf-life of bakery products but also improves the baking properties of bakery products. This review summarizes different types and action mechanisms of antifungal compounds produced by LAB, factors affecting the production of antifungal compounds, and the effects of antifungal LAB on bakery products, providing a reference for future applications of antifungal LAB in bakery products.

Tibetan Pig-Derived Probiotic Lactobacillus amylovorus SLZX20-1 Improved Intestinal Function via Producing Enzymes and Regulating Intestinal Microflora

The interaction between exogenous microorganisms and the host has received great attention, and finding new probiotics is always the way to improve the health of humans and animals. Lactobacillus amylovorus (L. amylovorus) is a kind of Lactobacillus that can efficiently utilize starch, as a food and feed additive, it has been widely used for mildew prevention and antibacterial, bacteriostasis, and enzyme production. Herein, a strain of L. amylovorus was isolated from the feces of Tibetan weaned piglets, named L. amylovorus SLZX20-1. Physiological and biochemical experiments in vitro confirmed that it had a fast growth rate and could produce a variety of enzymes, including α-galactosidase, β-galactosidase, α-glucosidase, β-glucosidase, and ferulic acid esterase. In addition, L. amylovorus SLZX20-1 exerted antibiotic effects on the growth of Salmonella typhimurium (S. typhimurium) SL1344, Citrobacter rodentium (C. rodentium) DBS100, Salmonella pullorum (S. pullorum) CVCC1791, Staphylococcus aureus (S. aureus) CVCC1882, Escherichia coli (E. coli) O157, E. coli K88, E. coli K99, and E. coli 987P, which are closely related to acid productivity, such as lactic acid and acetic acid. In vitro co-culture, L. amylovorus SLZX20-1 has shown the strong adhesion ability to intestinal porcine epithelial cells (IPEC-J2 cells) and activated IPEC-J2 cells with high expression of host defense peptides (HDPs), such as NK-Lysin, PEP2C, and PBD-1. In vivo experiment, via intragastric administration, L. amylovorus SLZX20-1 significantly improved the feed intake of mice, declined the crypt depth of jejunum and ileum, L. amylovorus SLZX20-1 changed the composition of intestinal microbes, especially at the level of colonic genus, the dominant genus was changed from Lactobacillus to S24-7, which indicated the change of intestinal carbohydrate nutrition. In conclusion, L. amylovorus SLZX20-1 showed strong probiotic characteristics, which met with the standard of probiotics and is worth further exploring its impacts on host health and its potential as a candidate strain of probiotics.

Limosilactobacillus (Lactobacillus) fermentum ALAL020, a Probiotic Candidate Bacterium, Produces a Cyclic Dipeptide That Suppresses the Periodontal Pathogens Porphyromonas gingivalis and Prevotella intermedia

Periodontal disease develops as a result of oral microbiota in dysbiosis, followed by the growth of periodontal pathogens such as Porphyromonas gingivalis and Prevotella intermedia. In case of acute symptoms, antibacterial agents and disinfectants are administered, however the appearance of drug-resistant bacteria and allergies cause problems. In recent years, studies on the effects of probiotics have been conducted as an alternative therapy for periodontitis. However, the basic mechanism of the inhibitory effect of probiotic bacteria on periodontal disease has not been clearly elucidated. To clarify the antibacterial mechanism of probiotics against periodontal pathogens, we used Limosilactobacillus (Lactobacillus) fermentum ALAL020, which showed the strongest antibacterial activity against P. gingivalis and P. intermedia among 50 screened lactic acid bacteria strains. The antibacterial substances produced were identified and structurally analyzed. After neutralizing the MRS liquid culture supernatant of ALAL020 strain, the molecular weight (m/z) of the main antibacterial substance separated by gel filtration column chromatography and reverse phase HPLC was 226.131. This low molecular weight compound was analyzed by LC-MS and disclosed the composition formula C₁₁H₁₈O₃N₂, however the molecular structure remained unknown. Then, structural analysis by NMR revealed C₁₁H₁₈O₃N₂ as the cyclic dipeptide, “hexahydro-7-hydroxy-3- (2-methylpropyl) pyrrolo [1,2-a] pyrazine-1,4-dion cyclo (Hyp-Leu) “. Based on the results of this analysis, cyclo (Hyp-Leu) was chemically synthesized and the antibacterial activity against P. gingivalis and P. intermedia was measured. The minimum inhibitory concentration (MIC) was 2.5 g/L and the minimum bactericidal concentration (MBC) was shown to be less than 5 g/L. In addition, an in vitro epithelial tissue irritation test at 10 g/L showed no tissue toxicity. So far there are no reports of this peptide being produced by probiotic bacteria. Furthermore, antibacterial activity of this cyclic dipeptide against periodontal disease bacteria has not been confirmed. The results of this study might lead to a comprehensive understanding of the antibacterial mechanism against periodontal disease bacteria in future, and are considered applicable for the prevention of periodontal disease.

Lactic Acid Bacteria from African Fermented Cereal-Based Products: Potential Biological Control Agents for Mycotoxins in Kenya

Cereals play an important role in global food security. Data from the UN Food and Agriculture Organization projects increased consumption of cereals from 2.6 billion tonnes in 2017 to approximately 2.9 billion tonnes by 2027. However, cereals are prone to contamination by toxigenic fungi, which lead to mycotoxicosis. The current methods for mycotoxin control involve the use of chemical preservatives. However, there are concerns about the use of chemicals in food preservation due to their effects on the health, nutritional quality, and organoleptic properties of food. Therefore, alternative methods are needed that are affordable and simple to use. The fermentation technique is based on the use of microorganisms mainly to impart desirable sensory properties and shelf-life extension. The lactic acid bacteria (LAB) are generally regarded as safe (GRAS) due to their long history of application in food fermentation systems and ability to produce antimicrobial compounds (hydroxyl fatty acids, organic acids, phenyllactic acid, hydrogen peroxide, bacteriocins, and carbon dioxide) with a broad range of antifungal activity. Hence, LAB can inhibit the growth of mycotoxin-producing fungi, thereby preventing the production of mycotoxins. Fermentation is also an efficient technique for improving nutrient bioavailability and other functional properties of cereal-based products. This review seeks to provide evidence of the potential of LAB from African fermented cereal-based products as potential biological agents against mycotoxin-producing fungi.

Lactic Acid Bacteria as Biopreservation Against Spoilage Molds in Dairy Products - A Review

Mold spoilage of dairy products such as yogurt is a concern in dairy industry. Not only does it lead to substantial food waste, economic losses, and even brand image damage, but it may also cause public health concern due to the potential production of mycotoxin. Good hygiene practices are necessary to prevent contamination, but contamination may nevertheless occur at the production site and, not least, at the site of the consumer. In recent years, there has been a growing interest from consumers for "clean label" food products, which are natural, less-processed, and free of added, chemical preservatives, and a wish for shelf lives of considerable length in order to minimize food waste. This has sparked an interest in using lactic acid bacteria (LAB) or their metabolites as biopreservatives as a way to limit the growth of spoilage organisms in dairy products. A range of compounds produced by LAB with potential antifungal activity have been described as contributing factors to the inhibitory effect of LAB. More recently, growth inhibition effects caused by specific competitive exclusion have been elucidated. It has also become clear that the sensitivity toward both individual antifungal compounds and competition mechanisms differ among molds. In this review, the main spoilage molds encountered in dairy products are introduced, and an overview of the antifungal activity of LAB against different spoilage molds is presented including the main antifungal compounds derived from LAB cultures and the sensitivity of the spoilage molds observed toward these compounds. The recent findings of the role of competitive exclusion with emphasis on manganese depletion and the possible implications of this for biopreservation are described. Finally, some of the knowledge gaps, future challenges, and trends in the application of LAB biopreservation in dairy products are discussed.

Characterization of Lacticaseibacillus rhamnosus, Levilactobacillus brevis and Lactiplantibacillus plantarum Metabolites and Evaluation of Their Antimicrobial Activity against Food Pathogens

Lactic acid bacteria (LAB) play an important role as natural food preservatives. However, the characterization of the variety of their metabolites is limited. The objective of this study was to determine the production of specific metabolites of Lacticaseibacillus rhamnosus, Levilactobacillus brevis and Lactiplantibacillus plantarum by an optimized liquid chromatography with an ultraviolet/diode detection (HPLC-UV/DAD) method and to investigate their potential antimicrobial activity against specific food pathogens. Based on the results of this study, the main metabolites detected in Levilactobacillus brevis were 103.4 μg mL−1 DL-p-Hydroxyphenyllactic acid (OH-PLA) and 2.59 μg mL−1 vanillic acid, while 216.2 μg mL−1 OH-PLA, 19.0 μg mL−1 salicylic acid, 3.7 μg mL−1 vanillic acid, 6.9 μg mL−1 ferulic acid, 4.2 μg mL−1 benzoic acid and 1.4 μg mL−1 4-Hydrocinnamic acid were identified in the Lactiplantibacillus plantarum strain and 147.6 μg mL−1 OH-PLA and 4.9 μg mL−1 ferulic acid were identified in Lacticaseibacillus rhamnosus. This study provides alternative approaches for the molecules involved in the antimicrobial activity of food microorganism fermentation. These molecules may be used as antimicrobial ingredients in the food industry instead of conventional chemical preservatives.

The impacts of antimicrobial and antifungal activity of cell-free supernatants from lactic acid bacteria in vitro and foods

Lactic acid bacteria (LAB) are distinguished by their ability to produce lactic acid, among other interesting metabolites with antimicrobial activity. A cell-free supernatant (CFS) is a liquid containing the metabolites resulting from microbial growth and the residual nutrients of the medium used. CFS from LAB can have antimicrobial activity due to organic acids, fatty acids, and proteinaceous compounds, among other compounds. This review aims to summarize the information about CFS production, CFS composition, and the antimicrobial (antibacterial and antifungal) activity of CFS from LAB in vitro, on foods, and in active packaging. In addition, the mechanisms of action of CFS on cells, the stability of CFS during storage, CFS cytotoxicity, and the safety of CFS are reviewed. The main findings are that CFS's antibacterial and antifungal activity in vitro has been widely studied, particularly in members of the genus Lactobacillus. CFS has produced strong inhibition of bacteria and molds on foods when applied directly or in active packaging. In most studies, the compounds responsible for antimicrobial activity are identified. A few studies indicate that CFSs are stable for 1 to 5 months at temperatures ranging from 4 to 35°C. The cytotoxicity of CFS on human cells has not been well studied. However, the studies that have been performed reported no toxicity of CFS. Therefore, it is necessary to investigate novel growth mediums for CFS preparation that are compatible with food sensory properties. More studies into CFS stability and cytotoxic effects are also needed.

Sourdoughs fermented by autochthonous Lactobacillus strains improve the quality of gluten-free bread

Sourdoughs based on fermentation by lactobacilli have the potential to produce gluten-free maize-based bread with acceptable technological and rheological characteristics, nutritional quality, and more prolonged shelf life. Of the 17 treatments compared (with or without sourdough, and involving single and multiple LAB species), treatments 12C (Lactobacillus brevis, L sanfranciscensis + L. plantarum), and 8C (L. brevis + L. paralimentarius) showed the lowest rate of complex modulus, while treatments 11C (L. sanfranciscensis + L. brevis + L. paralimentarius) and 2C (L. brevis) led to the greatest reduction in baking loss. The crumb moisture content of all of the formulations decreased with storage. Breads produced with treatment 2C (L. brevis) had the highest crumb moisture content when freshly baked, while loaves produced with treatment 3C (L. paralimentarius) had the highest crumb moisture content after four days of storage. A sensory evaluation indicated that sourdough-based maize breads were superior to both control and chemically acidified breads. The optimal treatments were to use sourdough seeded with treatment 2C (L. brevis), with treatment 4C (L. plantarum), with treatment 8C (L. brevis + L. paralimentarius), or with treatment 11C (L. sanfranciscensis + L. brevis + L. paralimentarius).

In Vitro Antagonistic Effect of Lactic Acid Bacteria Isolated from Fermented Beverage and Finfish on Pathogenic and Foodborne Pathogenic Microorganism in Ethiopia

Background

Lactic acid bacteria from fermented foods and fish can antagonistically inhibit the growth of foodborne pathogenic organism in fermented food and they stimulate the immune response to protect the fish from certain kinds of infections. The aim of this study was to evaluate the in vitro antagonistic activities of lactic acid bacteria isolated from fermented beverage (Borde) and finfish on foodborne pathogenic microorganisms.

Methods

Laboratory-based experimental study was conducted from May 1 to Sep 1, 2020. Total sample numbers were 60 samples of fermented beverage (Borde) and 20 of finfish which were collected from different households and Chamo Lake (Arba Minch, Ethiopia). Each sample was firstly homogenized and serial dilution was prepared and spread on MRS agar plates in order to isolate pure culture. Different biochemical tests were performed to identify isolated bacteria. Then, cell-free supernatant (CFS) was prepared from MRS culture and used in an antimicrobial assay that was performed by agar diffusion method. The effects of pH, temperature, and enzymes on antimicrobial activity were evaluated in the same test. Simultaneously, the effects of lactic acid bacteria on aflatoxin production and on the permeability of the membrane were also evaluated. Data were analyzed using one-way ANOVA and Tukey post hoc analysis was performed by SPSS 25 statistical software.

Result

A total of 40 lactic acid bacteria were isolated; among them, 4 lactic acid bacteria, belonging to the genera Enterococcus, Leuconostoc, and Weisellia from fermented beverage and Pediococcus from fish, were screened for antimicrobial activity. The cell-free supernatant of those four isolates exhibited a significant (p < 0.05) antibacterial effect against tested pathogens and foodborne pathogenic bacteria. In addition, CFS showed antifungal and antiaflatoxigenic activities. The antimicrobial compounds synthesized by these isolates were sensitive to some proteolytic enzymes, and they were proved to be stable at high temperatures. It maintained/retained antimicrobial activity in a wide range of pH 2.0–10. Enterococcal CFS exhibited antibacterial activity against S. aureus on membrane permeability, as confirmed by the increase in absorbance value between 0.075 and 0.24 at OD_280-nm and between 0.68 and 1.2 at OD_260-nm.

Conclusion

Cell-free supernatant produced by isolated lactic acid bacteria showed antimicrobial activity against a wide range of Gram-positive and Gram-negative foodborne bacteria, suggesting its potential application as a natural antimicrobial agent in tackling the rising drug resistance against foodborne pathogens.

Recent developments in antifungal lactic acid bacteria: Application, screening methods, separation, purification of antifungal compounds and antifungal mechanisms

Fungal contamination of food, which causes large economic losses and public health problems, is a global concern. Chemical methods are typically used in the food industry to inhibit the growth of spoilage fungus, but there are several drawbacks of chemical methods. Thus, the development of consumer-friendly and ecologically sustainable biological preservation technology has become a hot spot in food research. As a natural biological control agent, lactic acid bacteria (LAB) is a good choice in food preservation due to its antifungal properties. In order to screen and identify new antifungal LAB and antifungal compounds, this review compares three screening methods (overlay method, agar diffusion method, and microplate inhibition method) of antifungal LAB and summarizes the separation and purification techniques of antifungal compounds. A discussion of the effects of LAB, media, temperature, pH, and incubation period on the antifungal activity of LAB to highlight the antifungal properties of LAB for future studies then follows. Additionally, the antifungal mechanism of LAB is elucidated from three aspects: 1) LAB cells, 2) antifungal compounds, and 3) co-cultivation. Finally, research regarding antifungal LAB in food preservation (fruits, vegetables, grain cereals, bakery products, and dairy products) is summarized, which demonstrates the potential application value of LAB in food.

Multiple Techno-Functional Characteristics of Leuconostoc and Their Potential in Sourdough Fermentations

In this study, the potential of Leuconostoc as non-conventional sourdough starter cultures was investigated. A screening for antifungal activities of 99 lactic acid bacteria (LAB) strains revealed high suppression of bakery-relevant moulds in nine strains of Leuconostoc with activities against Penicillium sp., Aspergillus sp., and Cladosporium sp. Mannitol production was determined in 49 Leuconostoc strains with >30 g/L mannitol in fructose (50 g/L)-enriched MRS. Further, exopolysaccharides (EPS) production was qualitatively determined on sucrose (40 g/L)-enriched MRS agar and revealed 59 EPS positive Leuconostoc strains that harboured dextransucrase genes, as confirmed by PCR. Four multifunctional Lc. citreum strains (DCM49, DCM65, MA079, and MA113) were finally applied in lab-scale sourdough fermentations (30 °C, 24 h). Lc. citreum was confirmed by MALDI-TOF MS up to 9 log CFU/g and pH dropped to 4.0 and TTA increased to 12.4. Antifungal compounds such as acetic acid, phenyllactic and hydroxyphenyllactic acids were determined up to 1.7 mg/g, 2.1 µg/g, and 1.3 µg/g, respectively, mannitol up to 8.6 mg/g, and EPS up to 0.62 g/100 g. Due to the observed multifunctionalities and the competitiveness in the natural flour microbiota present in sourdoughs, non-conventional LAB genera such as Leuconostoc seem promising for application in sourdough-based bakery products.

The forgotten role of food cultures

Fermentation is one of if not the oldest food processing technique, yet it is still an emerging field when it comes to its numerous mechanisms of action and potential applications. The effect of microbial activity on the taste, bioavailability and preservation of the nutrients and the different food matrices has been deciphered by the insights of molecular microbiology. Among those roles of fermentation in the food chain, biopreservation remains the one most debated. Presumably because it has been underestimated for quite a while, and only considered - based on a food safety and technological approach - from the toxicological and chemical perspective. Biopreservation is not considered as a traditional use, where it has been by design - but forgotten - as the initial goal of fermentation. The 'modern' use of biopreservation is also slightly different from the traditional use, due mainly to changes in cooling of food and other ways of preservation, Extending shelf life is considered to be one of the properties of food additives, classifying - from our perspective - biopreservation wrongly and forgetting the role of fermentation and food cultures. The present review will summarize the current approaches of fermentation as a way to preserve and protect the food, considering the different way in which food cultures and this application could help tackle food waste as an additional control measure to ensure the safety of the food.

Screening of Antifungal Lactic Acid Bacteria as Bioprotective Cultures in Yogurt and a Whey Beverage

ABSTRACT

The demand for preservative-free food products is rising, and biopreservation is a potential alternative to replace or reduce the use of chemical preservatives. The objectives of this study were to assess the antifungal activity of lactic acid bacteria (LAB; n = 98) and the efficacy and applicability of the chosen bioprotective cultures against fungal spoilers in dairy products. First, 14 antifungal strains were preliminarily screened by in vitro tests against Pichia pastoris D3, Aspergillus niger D1, Geotrichum candidum N1, Kluyveromyces marxianus W1, and Penicillium chrysogenum B1 and validated by challenge tests in yogurt, indicating that the fungal-inhibiting activity of LAB was species specific and yogurt fermented with antifungal LAB cultures was more effective in extending shelf life. Second, the chosen 14 LAB strains were identified by the 16S rDNA sequence analysis and carbohydrate fermentation test. The results were as follows: nine strains were Lactobacillus plantarum, three were Lactobacillus paracasei, one was Enterococus faecium, and one was Lactobacillus rhamnosus. Among them, active L. plantarum N7 was the chosen and studied factor affecting antifungal activity by using the response surface methodology. Finally, in situ tests were conducted to validate the activity of L. plantarum N7 in actual dairy products (whey beverages). Physicochemical and microbial indices of whey beverages during storage indicated that antifungal L. plantarum N7 could slow yeast growth and be candidates of interest for industrial applications.

HIGHLIGHTS

Functional and Healthy Features of Conventional and Non-Conventional Sourdoughs

Sourdough is a composite ecosystem largely characterized by yeasts and lactic acid bacteria which are the main players in the fermentation process. The specific strains involved are influenced by several factors including the chemical and enzyme composition of the flour and the sourdough production technology. For many decades the scientific community has explored the microbiological, biochemical, technological and nutritional potential of sourdoughs. Traditionally, sourdoughs have been used to improve the organoleptic properties, texture, digestibility, palatability, and safety of bread and other kinds of baked products. Recently, novel sourdough-based biotechnological applications have been proposed to meet the demand of consumers for healthier and more natural food and offer new inputs for the food industry. Many researchers have focused on the beneficial effects of specific enzymatic activities or compounds, such as exopolysaccharides, with both technological and functional roles. Additionally, many studies have explored the ability of sourdough lactic acid bacteria to produce antifungal compounds for use as bio-preservatives. This review provides an overview of the fundamental features of sourdoughs and their exploitation to develop high value-added products with beneficial microorganisms and/or their metabolites, which can positively impact human health.

Effects of Lacto-Fermented Agricultural By-Products as a Natural Disinfectant against Post-Harvest Diseases of Mango (Mangifera indica L.)

Background: the antagonism activity of lactic acid bacteria metabolites has the potential to prevent fungal growth on mango. Methods: the potential of developing natural disinfectant while using watermelon rinds (WR), pineapple (PP), orange peels (OP), palm kernel cake (PKC), and rice bran (RB), via lacto-fermentation was investigated. The obtained lactic acid bacteria (LAB) metabolites were then employed and the in vitro antifungal activity toward five spoilage fungi of mango was tested through liquid and solid systems. Besides, the effect of the produced disinfectant on the fungal growth inhibition and quality of mango was investigated. Results: the strains Lactobacillus plantarum ATCC8014 and Lactobacillus fermentum ATCC9338 growing in the substrates PKC and PP exhibited significantly higher in vitro antifungal activity against Colletotrichum gloeosporioides and Botryodiplodia theobromae as compared to other tested LAB strains and substrates. The in-situ results demonstrated that mango samples that were treated with the disinfectant produced from PKC fermented with L. plantarum and L. fermentum had the lowest disease incidence and disease severity index after 16 days shelf life, as well as the lowest conidial concentration. Furthermore, PKC that was fermented by L. fermentum highly maintained the quality of the mango. Conclusions: lactic acid fermentation of PKC by L. fermentum demonstrated a high potential for use as a natural disinfectant to control C. gloeosporioides and B. theobromae on mango.

Impact of Storing Condition on Staling and Microbial Spoilage Behavior of Bread and Their Contribution to Prevent Food Waste

The high loss rate of bread is generally known to contribute to the alarmingly high numbers in worldwide food waste. Correct storage techniques are believed to enable the reduction of preventable food waste. Therefore, the influence of storage parameters on staling and spoilage behavior of German bread within the limits of common household methods was investigated in this study. The aim was to generate reliable data for staling and spoilage using different storage methods (PE-layered microperforated paper bag, plastic bag, and fridge and bread box) to bridge the gap between consumer’s needs and scientific research questions. Everyday routines of life, such as visual inspection, were compared with microbiological techniques and were found to represent an adequate tool for microbial safety control. Visually undetectable fungal growth has not been found to result in the production of mycotoxins (fumonisins B1 and B2 and ochratoxin A) in quantifiable or harmful concentrations. Thus, disgust should prevent any foodborne health risks as the visual appearance should lead to avoiding the consumption of spoiled food before mycotoxins are produced in amounts causing adverse health effects within the limits of this experimental setup. Additionally, the storage temperature especially was found to influence the kinetics of staling processes, as a reduction accelerated the staling process. Further, crumb moisture loss was found to contradict a long shelf life but, on the other hand, an elevated humidity was shown to provoke excessive microbial growth and should therefore be observed when designing suitable storage methods. Further, the correct choice of the bread type stored and a good sanitary practice represent simply accessible ways to prolong the storage period of bread loaves.

Leuconostoc citreum TR116 as a Microbial Cell Factory to Functionalise High-Protein Faba Bean Ingredients for Bakery Applications

Grain legumes, such as faba beans, have been investigated as promising ingredients to enhance the nutritional value of wheat bread. However, a detrimental effect on technological bread quality was often reported. Furthermore, considerable amounts of antinutritional compounds present in faba beans are a subject of concern. Sourdough-like fermentation can positively affect baking performance and nutritional attributes of faba bean flours. The multifunctional lactic acid bacteria strain Leuconostoc citreum TR116 was employed to ferment two faba bean flours with different protein contents (dehulled flour (DF); high-protein flour (PR)). The strain’s fermentation profile (growth, acidification, carbohydrate metabolism and antifungal phenolic acids) was monitored in both substrates. The fermentates were applied in regular wheat bread by replacing 15% of wheat flour. Water absorption, gluten aggregation behaviour, bread quality characteristics and in vitro starch digestibility were compared to formulations containing unfermented DF and PR and to a control wheat bread. Similar microbial growth, carbohydrate consumption as well as production of lactic and acetic acid were observed in both faba bean ingredients. A less pronounced pH drop as well as a slightly higher amount of antifungal phenolic acids were measured in the PR fermentate. Fermentation caused a striking improvement of the ingredients’ baking performance. GlutoPeak measurements allowed for an association of this observation with an improved gluten aggregation. Given its higher potential to improve protein quality in cereal products, the PR fermentate seemed generally more promising as functional ingredient due to its positive impact on bread quality and only moderately increased starch digestibility in bread.

Yeast population dynamics on air exposure in total mixed ration silage with sweet potato residue

To investigate the yeast population dynamics during air exposure in total mixed ration (TMR) silage containing sweet potato residue. TMR were ensiled in laboratory silos (1 kg) with or without two lactic acid bacteria strains, Lactobacillus plantarum (LP), and Lactobacillus amylovorus (LA). Fermentation characteristics were measured and yeast population was investigated by ITS1 region gene sequencing using Illumina MiSeq platform. All treatments were well ensiled, and L. amylovorus improved aerobic stability. During aerobic exposure, Pichia kudriavzevii was detected with increased relative abundance in all treatments and more relative abundant in LP. Pichia fermentans was more relative abundant in control. Higher relative abundance of Pichia anomala was detected in deteriorating LP. The relative abundance of Pichia ohmeri increased during later aerobic exposure in the control and LA, with a significant increase in the count of yeast population. Despite Cryptococcus was detected more relative abundant during early stage of aerobic exposure, the yeast population was below the detection limit. Aerobic deterioration was characterized by an increase in operational taxonomic units of Pichia. High relative abundance of P. anomala and P. kudriavzevii made aerobic deterioration easier. Inhibition of P. fermentans might be an effective strategy for improving the aerobic stability to some instance.

Evaluation of the bioprotectivity of Lactobacillus binary/ternary cultures in yogurt

The attempts toward addition of biocontrol agents in dairy products have gained popularity. Here, we worked on analysing the antifungal activity of binary and ternary combinations of three Lactic Acid Bacteria (LAB) against five spoilage yeasts in yogurt. The yogurt samples were characterized in terms of pH, acidity, WHC, textural parameters, viscosity, survivability and antifungal activity of LAB and sensorial properties during cold storage. The results showed that the inoculation of LAB in yogurt gave rise in significant reduction of pH throughout cold storage while titrable acidity and WHC decreased (p < .05). Inoculation of LAB resulted in significant increase in hardness and adhesiveness while springiness remained constant. On the other hand, apparent viscosity of all samples experienced a profound increase up to the 10th day of storage followed by a reduction trend for the rest of storage period. Analysis of inhibitory activity of LAB showed an efficient barrier against all five yeasts, in which the most activity was recorded for Lactobacillus reuteri followed by Lactobacillus acidophilus. On the other hand, the most resistance yeast was Kluyveromyces marxianus followed by Rhodotorula mucilaginosa. Sensorial analysis revealed that addition of LAB in yogurt brought about a profound improvement in textural quality of samples. Inoculation of LAB cultures in yogurt at 5% (v/v) not only could improve the physicochemical and sensorial properties of yogurt, but also could introduce a strategy toward substituting of chemical preservatives with biocontrol agents.

Exploitation of Lactic Acid Bacteria and Baker's Yeast as Single or Multiple Starter Cultures of Wheat Flour Dough Enriched with Soy Flour

Sourdough fermentation presents several advantageous effects in bread making, like improved nutritional quality and increased shelf life. Three types of experiments aimed to evaluate comparatively the efficiency of two Lactobacillus (Lb.) strains, Lb. plantarum ATCC 8014 and Lb. casei ATCC 393, to metabolize different white wheat flour and soybeans flour combinations to compare their efficiency, together with/without Saccharomyces cerevisiae on sourdough fermentation. For this purpose, the viability, pH, organic acids, and secondary metabolites production were investigated, together with the dynamic rheological properties of the sourdough. During sourdough fermentation, LAB presented higher growth, and the pH decreased significantly from above pH 6 at 0 h to values under 4 at 24 h for each experiment. Co-cultures of LAB and yeast produced a higher quantity of lactic acid than single cultures, especially in sourdough enriched with soy-flour. In general, sourdoughs displayed a stable, elastic-like behavior, and the incorporation of soy-flour conferred higher elasticity in comparison with sourdoughs without soy-flour. The higher elasticity of sourdoughs enriched with soy-flour can be attributed to the fact that through frozen storage, soy proteins have better water holding capacity. In conclusion, sourdough supplemented with 10% soy-flour had better rheological properties, increased lactic, acetic, and citric acid production.

Exploration of the Microbial Biodiversity Associated with North Apulian Sourdoughs and the Effect of the Increasing Number of Inoculated Lactic Acid Bacteria Strains on the Biocontrol against Fungal Spoilage

In this study, we explored the diversity of yeasts and lactic acid bacteria (LAB) associated with six spontaneous sourdough fermentations from the northern part of the Apulian region (Italy). Bacterial and yeast isolates from sourdough were investigated by amplified ribosomal DNA restriction analysis (ARDRA) and restriction fragment length polymorphism (RFLP) analysis, respectively. The identification of the isolates was confirmed by sequencing bacterial 16S gene and yeast ITS1–5.8S–ITS2 rRNA gene amplicons. Microbiological analysis of all sourdough samples revealed that LAB and yeast counts ranged between 1.7 × 105 and 6.5 × 108 cfu/g, and 7.7 × 105 and 2.5 × 107 cfu/g, respectively. The molecular identification at species level revealed the occurrence of Lactobacillus plantarum as the dominant LAB and Saccharomyces cerevisiae as the dominant yeast species in all different sourdough samples. Then, the ability of all isolated strains to inhibit and/or reduce the growth of several selected fungi was valued through the overlay method. In light of their antifungal performances, ten LAB strains were inoculated, singularly and in combination, in subsequent bread-making trials. Overall, we confirmed the potential of LAB to extend the shelf life of bread through spoilage inhibition and, for the first time, we observed a synergistic effect due to the combination of several isolated LAB on the inhibition behavior against selected fungal spoilage strains. Our findings suggest the exploration of a LAB-based approach in order to extend the shelf life of bread, reducing, at the same time, the use of chemical agents for food preservation.

Phenyllactic acid promotes cell migration and invasion in cervical cancer via IKK/NF-κB-mediated MMP-9 activation

Background

Persistent infection with high-risk human papillomavirus (hrHPV) is associated with cervical cancer development. This process involves the virus-encoded E6 and E7 oncoproteins, which are maintained and expressed during all malignant transformation stages. However, HPV alone is insufficient to drive tumor progression-related behaviors such as cervical cancer cell motility. In this study, we investigated the effect of phenyllactic acid (PLA), a phenolic acid phytochemical and biomarker for discriminating various cancers, on the metastatic potential of cervical cancer cells.

Methods

The effects of PLA on HPV16/18 E6/E7 expression, migratory and invasive behavior, and matrix metalloproteinases (MMPs) expression of cervical cancers cells were measured. Specific inhibitors were used to further investigate biological function and underlying mechanism of PLA modulated cell motility.

Results

PLA significantly promoted the migration and invasion of SiHa, HeLa, and C-33A cervical cancer cells as well as upregulated matrix metalloproteinase-9 (MMP-9) expression. Moreover, PLA treatment attenuated E6/E7 expression in SiHa and HeLa cells. Further molecular analysis showed that PLA activated the nuclear factor-kappa B (NF-κB) signaling pathway and increased the nuclear translocation of both IκBα and p65. Treating cervical cancer cells with an NF-κB inhibitor potently reversed PLA-induced migratory and invasive behavior, MMP-9 upregulation, and/or E6/E7 downregulation. The PLA-induced NF-κB activation and MMP-9 upregulation were mediated by IκB kinase-β (IKK-β) phosphorylation via PKC signals. The results suggested that SiHa, HeLa, and C-33A cells might undergo a similar process to enhance their motility in response to PLA, regardless of the HPV status.

Conclusions

Collectively, our study reveals a new biological function of PLA and elucidate the possible molecular role of PLA as a risk factor for triggering cervical cancer cell motility.

Lactic Acid Bacteria as Antifungal and Anti-Mycotoxigenic Agents: A Comprehensive Review

Fungal contamination of food and animal feed, especially by mycotoxigenic fungi, is not only a global food quality concern for food manufacturers, but it also poses serious health concerns because of the production of a variety of mycotoxins, some of which present considerable food safety challenges. In today's mega-scale food and feed productions, which involve a number of processing steps and the use of a variety of ingredients, fungal contamination is regarded as unavoidable, even good manufacturing practices are followed. Chemical preservatives, to some extent, are successful in retarding microbial growth and achieving considerably longer shelf-life. However, the increasing demand for clean label products requires manufacturers to find natural alternatives to replace chemically derived ingredients to guarantee the clean label. Lactic acid bacteria (LAB), with the status generally recognized as safe (GRAS), are apprehended as an apt choice to be used as natural preservatives in food and animal feed to control fungal growth and subsequent mycotoxin production. LAB species produce a vast spectrum of antifungal metabolites to inhibit fungal growth; and also have the capacity to adsorb, degrade, or detoxify fungal mycotoxins including ochratoxins, aflatoxins, and Fusarium toxins. The potential of many LAB species to circumvent spoilage associated with fungi has been exploited in a variety of human food and animal feed stuff. This review provides the most recent updates on the ability of LAB to serve as antifungal and anti-mycotoxigenic agents. In addition, some recent trends of the use of LAB as biopreservative agents against fungal growth and mycotoxin production are highlighted.

Discovery and Development of Novel Anti-fungal Peptides Against Foodspoiling Fungi

BACKGROUND

Despite the extensive research carried out to develop natural antifungal preservatives for food applications, there are very limited antifungal agents available to inhibit the growth of spoilage fungi in processed foods. Scope and Approach: Therefore, this review summarizes the discovery and development of antifungal peptides using lactic acid bacteria fermentation to prevent food spoilage by fungi. The focus of this review will be on the identification of antifungal peptides, potential sources, the possible modes of action and properties of peptides considered to inhibit the growth of spoilage fungi. Key Findings and Conclusions: Antifungal peptides generated by certain lactic acid bacteria strains have a high potential for applications in a broad range of foods. The mechanism of peptides antifungal activity is related to their properties such as low molecular weight, concentration and secondary structure. The antifungal peptides were proposed to be used as bio-preservatives to reduce and/or replace chemical preservatives.

Antifungal Activity of Lactobacillus pentosus ŁOCK 0979 in the Presence of Polyols and Galactosyl-Polyols

The antifungal activity of Lactobacillus pentosus ŁOCK 0979 depends both on the culture medium and on the fungal species. In the control medium, the strain exhibited limited antagonistic activity against indicator food-borne molds and yeasts. However, the supplementation of the bacterial culture medium with polyols (erythritol, lactitol, maltitol, mannitol, sorbitol, xylitol) or their galactosyl derivatives (gal-erythritol, gal-sorbitol, gal-xylitol) enhanced the antifungal properties of Lactobacillus pentosus ŁOCK 0979. Its metabolites were identified and quantified by enzymatic methods, HPLC, UHPLC-MS coupled with QuEChERS, and GC-MS. The presence of polyols and gal-polyols significantly affected the acid metabolite profile of the bacterial culture supernatant. In addition, lactitol and mannitol were used by bacteria as alternative carbon sources. A number of compounds with potential antifungal properties were identified, such as phenyllactic acid, hydroxyphenyllactic acid, and benzoic acid. Lactobacillus bacteria cultivated with mannitol synthesized hydroxy-fatty acids, including 2-hydroxy-4-methylpentanoic acid, a well-described antifungal agent. Scanning electron microscopy (SEM) and light microscopy confirmed a strong antifungal effect of L. pentosus ŁOCK 0979.