Screening of antifungal potentials of Lactobacillus helveticus KLDS 1.8701 against spoilage microorganism and their effects on physicochemical properties and shelf life of fermented soybean milk during preservation

Microbial community succession and its correlation with the dynamics of flavor compound profiles in naturally fermented stinky sufu

Wuhan stinky sufu is a traditional fermented soybean product with a short ripening period and unique flavor. The aim of this study was to explore the characteristic flavor compounds and core functional microbiota of naturally fermented Wuhan stinky sufu. The results indicated that 11 volatile compounds including guaiacol, 2-pentylfuran, dimethyl trisulfide, dimethyl disulfide, acetoin, 1-octen-3-ol, (2E)-2-nonenal, indole, propyl 2-methylbutyrate, ethyl 4-methylvalerate, nonanal were characteristic aroma compounds, and 6 free amino acids (Ser, Lys, Arg, Glu, Met and Pro) were identified as taste-contributing compounds. 4 fungal genera (Kodamaea, unclassified_Dipodascaceae, Geotrichum, Trichosporon), and 9 bacterial genera (Lysinibacillus, Enterococcus, Acidipropionibacterium, Bifidobacterium, Corynebacterium, Lactococcus, Pseudomonas, Enterobacter, and Acinetobacter) were identified as the core functional microbiota with positive effects on the production of flavor compounds. These findings would enhance the understanding of core flavor-producing microorganisms in naturally fermented soybean products and potentially provide guidance for enhancing the quality of sufu.

Biotechnological and Medical Aspects of Lactic Acid Bacteria Used for Plant Protection: A Comprehensive Review

The use of chemical pesticides in agriculture goes hand in hand with some crucial problems. These problems include environmental deterioration and human health complications. To eliminate the problems accompanying chemical pesticides, biological alternatives should be considered. These developments spark interest in many environmental fields, including agriculture. In this review, antifungal compounds produced by lactic acid bacteria (LABs) are considered. It summarizes the worldwide distribution of pesticides and the effect of pesticides on human health and goes into detail about LAB species, their growth, fermentation, and their antifungal compounds. Additionally, interactions between LABs with mycotoxins and plants are discussed.

Role of Lactic Acid Bacteria in Food Preservation and Safety

Fermentation of various food stuffs by lactic acid bacteria is one of the oldest forms of food biopreservation. Bacterial antagonism has been recognized for over a century, but in recent years, this phenomenon has received more scientific attention, particularly in the use of various strains of lactic acid bacteria (LAB). Certain strains of LAB demonstrated antimicrobial activity against foodborne pathogens, including bacteria, yeast and filamentous fungi. Furthermore, in recent years, many authors proved that lactic acid bacteria have the ability to neutralize mycotoxin produced by the last group. Antimicrobial activity of lactic acid bacteria is mainly based on the production of metabolites such as lactic acid, organic acids, hydroperoxide and bacteriocins. In addition, some research suggests other mechanisms of antimicrobial activity of LAB against pathogens as well as their toxic metabolites. These properties are very important because of the future possibility to exchange chemical and physical methods of preservation with a biological method based on the lactic acid bacteria and their metabolites. Biopreservation is defined as the extension of shelf life and the increase in food safety by use of controlled microorganisms or their metabolites. This biological method may determine the alternative for the usage of chemical preservatives. In this study, the possibilities of the use of lactic acid bacteria against foodborne pathogens is provided. Our aim is to yield knowledge about lactic acid fermentation and the activity of lactic acid bacteria against pathogenic microorganisms. In addition, we would like to introduce actual information about health aspects associated with the consumption of fermented products, including probiotics.

Potential Inhibitors of CYP51 Enzyme in Dermatophytes by Red Sea Soft Coral Nephthea sp.: In Silico and Molecular Networking Studies

In this study, the n-hexane fraction of soft coral Nephthea sp. gathered from the Red Sea was evaluated for its antidermatophyte activity. The antidermatophyte activity was performed versus different fungi, including Microsporum canis, Trichophyton gypseum, and Microsporum mentagrophytes, using a broth microdilution method. The n-hexane fraction showed minimum inhibitory concentrations (MICs) against the tested dermatophytes of 104.2 ± 20.8, 125 ± 0.0, and 83.33 ± 20.83 μg/mL respectively. The chemical constitution of the lipoidal matter (n-hexane fraction) was characterized by gas chromatography coupled with a mass spectrometer (GC-MS). The unsaponifiable fraction (USAP) of Nephthea sp. showed relative percentages of hydrocarbons and vitamins of 69.61% and 3.26%, respectively. Moreover, the percentages of saturated and unsaturated fatty acids were 53.67% and 42.05%, respectively. In addition, a molecular networking study (MN) of the GC-MS analysis performed using the Global Natural Products Social Molecular Networking (GNPS) platform was described. The molecular docking study illustrated that the highest binding energy score for spathulenol toward the CYP51 enzyme was -8.3674 kcal/mol, which predicted the mode of action of the antifungal activity, and then the results were confirmed by the inhibitory effect of Nephthea sp. against CYP51 with an IC₅₀ value of 12.23 μg/mL. Our results highlighted the antifungal potential of Nephthea sp. metabolites.

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.

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.

Probiotic based-diet effect on the immune response and induced stress in irradiated mass reared Ceratitis capitata males (Diptera: Tephritidae) destined for the release in the sterile insect technique programs

Ceratitis capitata (medfly) is one of the most devastating crop pests worldwide. The Sterile Insect Technique (SIT) is a control method that is based on the mass rearing of males, their sterilization, and release in the field. However, the effectiveness of the technique depends on the quality of the released males and their fitness. We previously isolated and selected a probiotic bacteria (Enterobacter sp.), from wild-caught medflies, according to criteria that improved biological quality traits of reared medfly males.We firstly evaluated the impact of the irradiation on the expression of different immune and stress genes in the medfly sterile males. Expression was measured at differents time points ranging from 0 to 168 h after irradiation to capture the response of genes with distinct temporal expression patterns. Then, we supplemented the larval diet with previously isolated Enterobacter sp.strain, live and autoclaved at various concentrations to see whether the probiotic treatments affect, through their protective role, the gene expression level, and quality traits. The irradiation had significant effect on the genes attacin, cecropin, PGPR-LC, hsp23, and hsp70 level expression. The expression of attacin and PGPR-LC was up-regulated while that of cecropin was down-regulated. Hsp genes showed decreased levels between 0 and 18 h to peak at 72 h. However, the supplementation of the probiotic strain, either live or autoclaved, was statistically significant only for attacingene. However, significant interaction time x probiotic was noticed for attacin, cecropin, hsp23 and hsp70. The probiotic treatments also improved the quality control parameters like pupal weight. From this work we can conclude that a consortium of parabiotics (autoclaved probiotics) treatment will be recommended in insectaries considering both the beneficial effects on mass reared insects and its general safety for insectary workers and for environment.

Update of Probiotics in Human World: A Nonstop Source of Benefactions till the End of Time

Lactic acid bacteria (LAB) are known for their biotechnological potential. Moreover, LAB are distinguished by amazing criteria: Adjusting the intestinal environment, inhibiting pathogenic microbes in the gastrointestinal tract, ability to reduce pathogen adhesion activity, improving the balance of the microbiota inside the intestine, capabilities of regulating intestinal mucosal immunity, and maintaining intestinal barrier function. The escalating number of research and studies about beneficial microorganisms and their impact on promoting health has attracted a big interest in the last decades. Since antiquity, various based fermented products of different kinds have been utilized as potential probiotic products. Nevertheless, the current upsurge in consumers' interest in bioalternatives has opened new horizons for the probiotic field in terms of research and development. The present review aims at shedding light on the world of probiotics, a continuous story of astonishing success in various fields, in particular, the biomedical sector and pharmaceutical industry, as well as to display the importance of probiotics and their therapeutic potential in purpose to compete for sturdy pathogens and to struggle against diseases and acute infections. Shadows and future trends of probiotics use are also discussed.

Lactobacillus delbrueckii subsp. bulgaricus KLDS 1.0207 Exerts Antimicrobial and Cytotoxic Effects in vitro and Improves Blood Biochemical Parameters in vivo Against Notable Foodborne Pathogens

Globally, foodborne diseases (FBDs) result in millions of sicknesses and deaths annually. Cumulative evidence suggests that the use of probiotic lactic acid bacteria (LAB) strains could be a viable alternative in inhibiting the activities of foodborne pathogens. This study aims to evaluate the in vitro antimicrobial, cytotoxic, and tolerance levels of Lactobacillus bulgaricus KLDS 1.0207 against two notable foodborne pathogens – Escherichia coli ATCC25922 and Staphylococcus aureus ATCC25923. Afterward, a 48 BALB/c mice-trial was used to assess its ameliorative effects on weight and serum biochemical parameters. Results showed that the cell-free supernatant (CFS) of this strain significantly inhibited both pathogens, but these effects were abolished at pH 6.5 and 7.0 (P < 0.05). Also, 6.96 ± 0.02 log CFU mL^–1 of L. bulgaricus KLDS 1.0207 was still viable after three hours in simulated gastric juice and at pH 3.0, indicating that this strain was a potential probiotic candidate. Also, inflammatory activities in RAW264.7 cells were significantly inhibited using 10⁹ CFU mL^–1 of L. bulgaricus KLDS 1.0207 cells (P < 0.05). Significant weight losses were also prevented in the T_LBSA (from 19.42 ± 1.04 to 19.55 ± 0.55 g) and T_LBEC (from 22.86 ± 0.90 to 14.77 ± 9.86 g) groups compared to their respective model groups (T_SA – from 21.65 ± 1.80 to 20.14 ± 1.84, and T_EC – from 21.45 ± 0.82 to 14.45 ± 9.70 g). Besides, there was a slight weight gain in the S. aureus prevention group (T_LBSA) compared to the model group (T_SA). Serum biochemical analyses revealed that the total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), and some mineral levels were markedly increased by S. aureus and E. coli administrations but were reversed to normalcy in both prevention groups (T_LBSA and T_LBEC). Interestingly, high-density lipoprotein (HDL) levels, which were initially disrupted in the model groups, were restored in the prevention groups (T_LBSA and T_LBEC). This study presents L. bulgaricus KLDS 1.0207 as a promising probiotic candidate with antimicrobial, anti-inflammatory, acid, and bile tolerant and lipid-regulating applications. It also gives valuable insights for targeted future in vivo treatment and prevention studies involving other probiotic LAB candidates. Future in vivo studies elucidating specific mechanisms behind the in vitro antimicrobial, cytotoxic, and in vivo ameliorative effects are warranted.

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.

Bio-functional properties of probiotic Lactobacillus: current applications and research perspectives

Lactic acid bacteria as a starter culture are very important component in the fermentation process of dairy and food industry. Application of lactic acid bacteria as probiotic bacteria adds more functionality to the developed product. Gut colonizing bacteria have attractive benefits related to human health. Bio-functional properties such as antimicrobial activity, anti-inflammatory, ACE-inhibitory, antioxidant, antidiarrheal, antiviral, immunomodulatory, hypocholesterolemic, anti-diabetic and anti-cancer activities are the most applicable research areas of lactic acid bacteria. Different strains of Lactobacillus are generally consumed as probiotics and colonize the gastrointestinal tract. Sometimes these bacteria may possess antimicrobial activity and may positively influence the effect of antibiotics. Use of Lactobacillus spp. for the development of functional foods is one of the promising areas of current research and applications. Individual bacterial species have unique biological activity, which may vary from strains to strains and identification of this uniqueness could be helpful in the development of functional and therapeutic food products.

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.

Inhibitory effects of Inula britannica extract fermented by Lactobacillus plantarum KCCM 11613P on coagulase activity and growth of Staphylococcus aureus including methicillin-resistant strains

The aim of this study was to evaluate the antimicrobial efficacy of fermented Inula britannica extract (FIBE) against Staphylococcus aureus strains including methicillin-resistant S. aureus (MRSA). I. britannica extract was fermented by Lactobacillus plantarum KCCM 11613P, and the pathogenicity of S. aureus strains was determined via assessment of coagulase, DNase, and hemolytic activities. Epicatechin concentration increased from 4.38 to 6.05 μg/mg during fermentation (p < 0.01). FIBE treatment inhibited coagulase release from S. aureus to levels below the inhibitory concentration. FIBE promoted the release of intracellular nucleic acids and N-phenyl-1-naphthylamine absorption. In three S. aureus strains, damaged cells exhibited 21.58, 16.79, and 17.65% decreases in membrane potential induced by cell membrane depolarization, respectively (p < 0.05). Upon FIBE treatment in culture, the minimum inhibitory concentration of FIBE exerted a bacteriostatic effect. In conclusion, FIBE possesses antimicrobial properties, including inhibition of virulence factors, damage to cell membranes, and inhibition of bacterial growth. PRACTICAL APPLICATIONS: Methicillin-resistant Staphylococcus aureus (MRSA) is a serious concern in hospitals because of its known antibiotic resistance. Vancomycin and tigecycline are used for treating MRSA, but the appearance of vancomycin-intermediate and multidrug-resistant strains of these bacteria has created a demand for new antimicrobial agents. This study demonstrates the effective application of Inula britannica and fermentation technology for developing natural antimicrobial agents against methicillin-resistant Staphylococcus aureus.

Safety Assessment of Lactobacillus helveticus KLDS1.8701 Based on Whole Genome Sequencing and Oral Toxicity Studies

Lactobacillus helveticus KLDS1.8701 isolated from Chinese traditional fermented dairy product has been shown earlier to possess probiotic potentials but it is important to evaluate its safety in view of its possible use as a probiotic. The aim of the present study is to critically assess the safety of L. helveticus KLDS1.8701 through multiple perspectives. The complete genome of L. helveticus KLDS1.8701 was sequenced to mine for safety-associated genes. The minimum inhibitory concentrations of 15 antimicrobials and the adverse metabolites were determined. Standard acute oral and subacute toxicity studies were conducted in rats. The results in silico disclosed that the genome of L. helveticus KLDS1.8701 carries no transferable antibiotic resistance genes, no virulence factors and only 3 genes related to adverse metabolites. In vitro results showed that L. helveticus KLDS1.8701 was resistant against 6 antimicrobials and did not raise safety concerns about biogenic amine, D-lactic acid and nitroreductase. The results in vivo revealed that no adverse effects on experimental rats were observed in the oral toxicity tests. Overall, findings from this study suggest that L. helveticus KLDS1.8701 is safe and can be used as a potential probiotic for human consumption.

Antifungal Microbial Agents for Food Biopreservation-A Review

Food spoilage is a major issue for the food industry, leading to food waste, substantial economic losses for manufacturers and consumers, and a negative impact on brand names. Among causes, fungal contamination can be encountered at various stages of the food chain (e.g., post-harvest, during processing or storage). Fungal development leads to food sensory defects varying from visual deterioration to noticeable odor, flavor, or texture changes but can also have negative health impacts via mycotoxin production by some molds. In order to avoid microbial spoilage and thus extend product shelf life, different treatments—including fungicides and chemical preservatives—are used. In parallel, public authorities encourage the food industry to limit the use of these chemical compounds and develop natural methods for food preservation. This is accompanied by a strong societal demand for ‘clean label’ food products, as consumers are looking for more natural, less severely processed and safer products. In this context, microbial agents corresponding to bioprotective cultures, fermentates, culture-free supernatant or purified molecules, exhibiting antifungal activities represent a growing interest as an alternative to chemical preservation. This review presents the main fungal spoilers encountered in food products, the antifungal microorganisms tested for food bioprotection, and their mechanisms of action. A focus is made in particular on the recent in situ studies and the constraints associated with the use of antifungal microbial agents for food biopreservation.

Some current applications, limitations and future perspectives of lactic acid bacteria as probiotics

Several mechanism and non-mechanism-based studies supporting the claim that lactic acid bacteria (LAB) strains confer health benefits and play immune-modulatory roles were examined in this review. Probiotic applications of LAB on global burdens such as obesity and type-2 diabetes were discussed as well as the use of yoghurt and ice cream as important vehicles to convey several beneficial LAB strains. Probiotic and symbiotic dairy products may be used in the nearest future to treat a variety of health disorders. Current studies suggest that lactic acid bacteria possess anti-obesity and anti-diabetic propensities on their hosts and thus can play a crucial role in human health care. Research in the rheological and physicochemical properties of ice cream as well as its applications are also on the increase. These applications face certain hurdles including technological (for less developed countries), consumer acceptability of new functional foods may be influenced by culture, ethics or religion. There is need for more studies on the genetic basis for probiotic properties which will give further understanding regarding novel manipulation skills and applicability in nutrition and health sectors. More studies confirming the direct effects of probiotic LABs in lowering the spread of food-borne and other pathogens are also anticipated.