Food Spoilage Microorganisms Research Articles

Antimicrobial activity evaluation of combinations of essential oils, thymol and R-limonene against food-borne pathogens and spoilage agents

The application of essential oils has been shown to be an effective and sustainable alternative against the multiplication of spoilage and pathogenic microorganisms in food. The aim of this work was to study the antimicrobial activity effect of Cerrado Rosemary (Baccharis dracunculifolia DC.), Pepper Rosemary (Lippia sidoides Cham.), Mandarin (Citrus nobilis Lour.), Mexican Lime (Citrus aurantifolia Swingle) essential oils, and the thymol and R-limonene compounds against strains of Penicillium expansum, Pichia kudriavzevii, Salmonella Thypimurium and Staphylococcus aureus. The essential oils were characterized in terms of their chemical composition, the Minimum Inhibitory Concentration, and Minimum Bactericidal and Fungicidal Concentration; using the microdilution method in 96-well plates. In addition, effects from mixtures of the essential oils, and the isolated compounds in sub-inhibitory concentrations were performed. The Pepper Rosemary essential oil and thymol, separately, showed the lowest Minimum Inhibitory Concentration values against all the microorganisms evaluated, with the lowest ranging from 0.03 to 1.25 mg. mL−1 for P. expansum and 0.31–1.25 mg. mL−1 for S. Thypimurium. Mandarin and Mexican lime, have an enhanced antimicrobial effect when used in mixture. The R-limonene compound showed a synergistic additive effect when combined with the essential oils, against S. aureus strains only. The application of thymol and Lippia was able to reduce growth by 3 log10 for S. aureus and S. Typhimurium in 24 h. Therefore, the Pepper Rosemary essential oil, applied freely or in combination with the thymol compound, has greater potential for use as an antifungal and bactericidal agent, against the microorganisms evaluated.

Antimicrobial properties of Citrus maxima flavedo extracts against food pathogens and spoilage microorganisms

This study assesses the antimicrobial potential of ethyl acetate and dichloromethane extracts obtained from pomelo, Citrus maxima (C. maxima), flavedo against various food pathogens and spoilage microorganisms. The antimicrobial activities of these extracts were evaluated using the agar disc diffusion method against gram-positive bacteria (Bacillus cereus), Staphylococcus aureus and gram-negative bacteria (Escherichia coli). The results indicated that both extracts demonstrated antibacterial properties against the tested microorganisms. The ethyl acetate extract exhibited significantly higher antibacterial activity against the majority of bacterial strains compared to the dichloromethane extract, particularly against S. aureus and B. cereus. However, dichloromethane extract showed a better effect on E. coli, with the inhibition zone ranging from 8.7 to 11.3 mm. S. aureus displayed the highest sensitivity to ethyl acetate and dichloromethane extracts of pomelo flavedo with inhibition zones ranging from 1.3 to 1.5 mm, respectively. In conclusion, the findings suggest that pomelo extracts have significant potential as natural antimicrobials and can be safely utilized as food preservatives. This highlights the value of pomelo as a potential source of antimicrobial compounds for food safety and preservation purposes.

Biofilm Formation and Genotypic Characterization of Bifidobacteria from Yoghurt Samples and Food Supplements

This study evaluates the ability of yoghurt and supplement isolated Bifidobacterium species to generate biofilms through characterization of ITS region genes associated with biofilm formation. The objective of this project is to gain a better understanding of the ability of probiotic Bifidobacteria to build biofilms, which is thought to be beneficial for maintaining intestinal microbial balance and reducing the amount of pathogenic and food-spoilage microorganisms. This work is distinctive because it aims to close a knowledge gap on the ability of Bifidobacterium species isolated from yoghurts and supplements to form biofilms. Giving important details on prospective applications for these probiotic Bifidobacterium species, particularly in the biomedical and food industries. Samples including yoghurt samples and food supplements will be cultured using RCA (Reinforced Clostridial Agar) media. The Bifidobacteria will be isolated and then identified using morphological and biochemical analysis. 9 controls of bacteria with established biofilm forming potential will be run. The crystal violet assay will be used to evaluate the ability of various microbes to produce biofilms, and the DNA extraction for the samples and controls will be performed following ITS-PCR for the genotypic characterization. The DNA of the isolated Bifidobacterium species will be run through a gel electrophoresis procedure to determine its size. Comparison of the biofilm forming potential of Bifidobacterium species isolated from yoghurt and food supplements with that of pathogenic bacteria known to build biofilms may provide light on the utilization of probiotics to avoid infections from several pathogens.

DETERMINATION OF ANTIBIOSIS OF Trichoderma species AGAINST FUNGI ASSOCIATED WITH CORN (Zea Mays L.) SPOILAGE

Biological control of food spoilage microorganisms is gaining more attention because it is a safe and cheap technique. This study evaluated the antagonistic potential of Trichoderma species against corn spoilage fungi by plate co-culture technique for seven days. Fungal isolates from corn spoilage were examined morphologically and microscopically. The percentage growth inhibition (PGI) of Trichoderma species against the corn spoilage fungi were A. flavus (15%), A. niger (14%), A. terreus (62.9%), Fusarium spp. (5.9%), Nigrospora spp. (61.4%) and Penicillium spp. (62.5%). The result obtained in this study revealed that Trichoderma spp. had significant inhibitory effects against the growth of fungal pathogens associated with corn spoilage. Therefore, it could be explored for control of post-harvest fungal spoilage of corn. It is recommended that in order to compare the antagonistic strength of the Trichoderma species, different species of Trichoderma should be tested against the same spoilage fungi.

Antimicrobial Activity of Caesalpinia pulcherrima (L.) Leaves Extracts against Food Borne Pathogenic and Spoilage Microorganisms

With continuous increase in the human population, the cases of food poisoning and spoilage are on the rise. Such spoilage of foods to avoid the growth of unwanted microorganisms in order to protect from poisoning is generally achieved by the use of preservatives. But due to continuous exposure of the microorganism with the same preservatives have been resulted to create resistance against it. So, in order to search for the new preservatives, the petroleum ether, chloroform, acetone, methanol and aqueous extracts of Caesalpinia pulcherrima (L.) leaves have been examined against Bacillus cereus, Escherichia coli and Aspergillus niger HN-2 microorganisms for antimicrobial activity. The conducted experimental results clearly indicated about its ability to restrict the growth of tested microorganisms generally responsible for food poisoning and spoilage. Since, the previous reported toxicity studies already showed its safety profile, these plant extracts can surely be the matter of alternative choice as food preservatives.

Lysozyme Peptides as a Novel Nutra-Preservative to Control Some Food Poisoning and Food Spoilage Microorganisms.

Foodborne illnesses and microbial food contamination are crucial concerns and still issues of great worldwide concern. Additionally, the serious health hazards associated with the use of chemical preservatives in food technology. Lysozyme (Lz) is an active protein against Gram-positive bacterial cell wall through its muramidase lytic activity; however, several authors could identify some antimicrobial peptides derived from Lz that have an exaggerated and broad-spectrum antibacterial activity. Therefore, a lysozyme peptides preparation (LzP) is developed to broaden the Lz spectrum. In this work, we investigated the potential efficacy of LzP as a novel Nutra-preservative (food origin) agent against some pathogenic and spoilage bacteria. Our results showed that LzP demonstrated only 11% of the lysozyme lytic activity. However, LzP exhibited strong antibacterial activity against Escherichia coli, Salmonella enteritidis, and Pseudomonas species, while Salmonella typhi and Aeromonas hydrophila exhibited slight resistance. Despite the lowest LzP concentration (0.1%) employed, it performs stronger antibacterial activity than weak organic acids (0.3%). Interestingly, the synergistic multi-component formulation (LzP, glycine, and citric acid) could inhibit 6 log10 cfu/ml of E. coli survival growth. The effect of heat treatment on LzP showed a decrease in its antibacterial activity at 5 and 67% by boiling at 100 °C/30 min, and autoclaving at 121 °C/15 min; respectively. On the other hand, LzP acquired stable antibacterial activity at different pH values (4-7). In conclusion, LzP would be an innovative, natural, and food origin preservative to control the growth of food poisoning and spoilage bacteria in food instead chemical one.

Development of a novel hybrid antimicrobial peptide for enhancing antimicrobial spectrum and potency against food-borne pathogens.

To address the increasingly serious challenge of the transmission of foodbrone pathogens in the food chain. In this study, we employed rational design strategies, including truncation, amino acid substitution, and heterozygosity, to generate seven engineered peptides with α-helical structure, cationic property, and amphipathic characteristics based on the original Abhisin template. Among them, as the hybird antimicrobial peptide (AMP), AM exhibits exceptional stability, minimal toxicity, as well as broad-spectrum and potent antimicrobial activity against foodborne pathogens. Besides, it was observed that the electrostatic incorporation demonstrates by AM results in its primary targeting and disruption of the cell wall and membrane of Escherichia coli O157: H7 (EHEC) and methicillin-resistant Staphylococcus aureus (MRSA), resulting in membrane perforation and enhanced permeability. Additionally, AM effectively counteracts the deleterious effects of lipopolysaccharide, eradicating biofilms and ultimately inducing the demise of both food spoilage and pathogenic microorganisms. The findings highlight the significant potential of AM as a highly promising candidate for a novel food preservative and its great importance in the design and optimization of AMP-related agents.

In search of natural preservatives: Evaluation of Artocarpus heterophyllus lam leaves extracts against food spoilage microorganisms

In search of natural preservatives: Evaluation of Artocarpus heterophyllus lam leaves extracts against food spoilage microorganisms

The effect of carrageenan-gluten ratio and garlic essential oil concentration on physical, mechanical, and antimicrobial properties of edible film

Edible film can be made from natural polymers, such as fats, proteins, and polysaccharides. The combination of polysaccharides and proteins has the potential to form a film, it can improve the mechanical properties and physical properties of the film based on the complex structure formed. Furthermore, to improve the barrier properties by obstructing water vapour transmission and preventing the proliferation of spoilage microorganisms in food, it is important to present both hydrophobic substances and active compounds extracted from essential oils. This research aimed to find out the best formulation of gluten and garlic essential oil on the physical, mechanical, and bacteria-inhibitory properties of edible film. The method used in this research is the edible film made by combining carrageenan and gluten in several concentrations (7,5%; 10%; and 12,5%) and the addition of garlic essential oil at different concentrations (0%, 2%, and 4%), then observations were made on several test parameters such as solubility in water, thickness, water vapor transmission rate, tensile strength, and antibacterial properties of the film. Results obtained in the research demonstrated that the finest edible film treatment was found in addition of 12.5% gluten and addition of 4% garlic essential oil with the results of solubility parameter of 40.57% thickness of 0.73 mm tensile strength of 0.0009 N/mm2 and WVTR of 21.856 g/h/m2 and antibacterial properties against E. coli bacteria of 26.93 mm and against S. aurerus bacteria of 33.76 mm. This research concluded the addition of gluten and garlic oil could improve physical, mechanical, and antimicrobial properties edible film.

A review and comparative perspective on health benefits of probiotic and fermented foods

SummaryFermented foods such as yogurt, kefir and sauerkraut have been part of the human diet throughout history and have gained attention in recent years due to their immense health and nutritional benefits. As a result, fermented foods are considered biofuel for the human microbiome which helps to boost the immune system. Fermented foods are those foods and beverages that are produced by employing specific microbial‐based fermentation aids such as yeasts and bacteria, particularly lactic acid bacteria (LAB). Through controlled enzymatic reactions, these microbial cultures transform food components as substrates into value‐added products promoting various healthy fermentative activities. These microbes in fermented foods also produce compounds that can inhibit food spoilage and pathogenic microorganisms, thereby extending the product shelf of fermented products. Probiotics are live microbiota with beneficial health properties, prevent gastrointestinal diseases and modulate the human microbiome. Thus, foods that are fermented by certain strains of probiotic bacteria that exhibit evidence of health benefits are referred to as probiotic fermented foods. This review describes fermented and functional foods, probiotics and their relationship to human health. In addition, we offer our perspective on the distinct differences between probiotic and fermented foods to promote awareness for consumers and key stakeholders regarding these highly functional and nutritionally fermented food products.

Advances, limitations, and considerations on the use of vibrational spectroscopy towards the development of management decision tools in food safety.

Food safety and food security are two of the main concerns for the modern food manufacturing industry. Disruptions in the food supply and value chains have created the need to develop agile screening tools that will allow the detection of food pathogens, spoilage microorganisms, microbial contaminants, toxins, herbicides, and pesticides in agricultural commodities, natural products, and food ingredients. Most of the current routine analytical methods used to detect and identify microorganisms, herbicides, and pesticides in food ingredients and products are based on the use of reliable and robust immunological, microbiological, and biochemical techniques (e.g. antigen-antibody interactions, extraction and analysis of DNA) and chemical methods (e.g. chromatography). However, the food manufacturing industries are demanding agile and affordable analytical methods. The objective of this review is to highlight the advantages and limitations of the use of vibrational spectroscopy combined with chemometrics as proxy to evaluate and quantify herbicides, pesticides, and toxins in foods.

Effect of Different pHs and Temperatures on Stability and Mode of Action of Musa paradisiaca L. Flower Extract against Foodborne Pathogens and Food Spoilage Microorganisms

Raw foods contain harmful microorganisms that can infect processed foods and cause them to spoilage. To ensure safety and sustainability, processed foods are categorized depending on the required level of heat treatment and pH levels. This study aimed to assess the effect of different pHs and temperatures on the stability and mode of action of M. paradisiaca L. flower extract. The inhibition zone results after treating extracts with different pHs (3, 6, 7, and 11) for pathogenic bacteria and food spoilage ranged between 6.33 ± 0.47 to 16.67 ± 0.94 mm, and 6.00 ± 0.00 to 10.00 ± 0.00 mm, respectively. In terms of temperatures for foodborne pathogens (30, 50 and 80°C), E. coli showed the highest inhibition zone (11.67 ± 0.47 mm) at 30°C, while B. megaterium (12.00 ± 0.94 mm and 12.33 ± 0.47 mm) at 50 and 80°C. For the food fungi, C. krusei and C. parapsilosis showed the highest inhibition zone (8.33 ± 1.25 mm). The highest cell constituent release was at the concentration of 4×MIC for 4 and 96 h incubation and was found to be at 2.069%, 1.621%, 1.428%, and 1.643% for B. subtilis, E. coli, C.albicans and Asp. niger, respectively. The highest crystal violet uptake for B. subtilis, E. coli, C. albicans, and Asp. niger was 1.881, 2.082, 2.329, and 0.982 at 4׳ MIC after treatment for 4 and 96 h, respectively. In conclusion, M. paradisiaca L. flower extract exhibited antimicrobial activity, which showed stability after being subjected to different pHs and temperatures and can be developed as a natural sanitizing agent for washing raw foodstuffs.

Inhibition of Aspergillus carbonarius growth and Ochratoxin A production using lactic acid bacteria cultivated in an optimized medium

The Gram-positive bacteria lactic acid bacteria (LAB) are used in the food industry but are also known for inhibiting certain food spoilage microorganisms, especially fungi. Sources of nitrogen (N) for culture media are generally organic and expensive. Many attempts have been made to formulate economical culture media with alternative N sources obtained from agricultural and industrial byproducts. This study describes the design and optimization of an inexpensive culture medium for Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) MZ809351 strain B31. The culture medium was optimized using statistical experimental designs to identify the factors with the most significant effects on biomass concentration to reduce the overall cost, aiming to obtain a biomass concentration similar to that obtained with the reference LAB culture medium (de Man, Rogosa and Sharpe; MRS). Sodium acetate and magnesium sulfate were the most significant factors (p < 0.005), and their contents were reduced by 22 % and 40 %, respectively, without affecting biomass concentration. Malt germ extract (MGE) was used as an alternative nitrogen source to replace meat extract (ME) and proteose peptone (PP). Through these experiments, the composition of a culture medium that is less expensive than MRS broth was defined, which produced a biomass concentration (3.8 g/L) similar to that obtained with MRS medium. The inhibitory effects of two LAB strains isolated from the Ivory Coast and Mexico on the growth and production of ochratoxin A (OTA) in an ochratoxigenic fungus was tested. The minimum cellular concentration of the LAB to prevent the development of Aspergillus carbonarius Ac 089 and the production of OTA was determined in a model assay in Petri dishes. The conditions to inhibit the germination of A. carbonarius Ac 089 and the production of OTA were found. Using the optimized medium and a ratio of 2 × 104 LAB/spore (1 × 108 CFU/mL) strain B7 (L. plantarum MZ809351) and 2 × 103 LAB/spore (1 × 107 CFU/mL) strain B31 (L. plantarum MN922335) completely inhibited the growth of the fungus. A ratio of 2 × 105 LAB/spore (1 × 109 CFU/mL) was required to inhibit OTA production with strains B7 and B31. This study indicates the potential of cultivating LAB in an optimized and inexpensive culture medium for use as a biological control agent against ochratoxigenic fungi in food.

Antimicrobial and Antibiofilm Potential of Thymus vulgaris and Cymbopogon flexuosus Essential Oils against Pure and Mixed Cultures of Foodborne Bacteria.

The spread of pathogenic and food spoilage microorganisms through the food chain still faces major mitigation challenges, despite modern advances. Although multiple cleaning and disinfection procedures are available for microbial load reduction in food-related settings, microbes can still remain on surfaces, equipment, or machinery, especially if they have the ability to form biofilms. The present study assessed the biofilm-forming properties of pure and mixed cultures of foodborne and spoilage bacteria (Listeria monocytogenes, Enterococcus faecalis, Aeromonas hydrophila, Brochothrix thermosphacta), using polystyrene and stainless steel contact surfaces. Subsequently, the antimicrobial and antibiofilm properties of Thymus vulgaris and Cymbopogon flexuosus essential oils-EOs-were evaluated against these bacteria. Moreover, in silico prediction of the absorption and toxicity values of the EOs' major constituents was also performed, perceiving the putative application in food-related settings. Overall, biofilm formation was observed for all microbes under study, at different temperatures and both contact surfaces. In polystyrene, at 25 °C, when comparing pure with mixed cultures, the combination Listeria-Aeromonas achieved the highest biofilm biomass. Moreover, at 4 °C, increased biofilm formation was detected in stainless steel. Regarding thyme, this EO showed promising antimicrobial features (especially against A. hydrophila, with a MIC of 0.60 µg/µL) and antibiofilm abilities (MBEC of 110.79 µg/µL against L. monocytogenes, a major concern in food settings). As for lemongrass EO, the highest antimicrobial activity, with a MIC of 0.49 µg/µL, was also observed against L. monocytogenes. Overall, despite promising results, the in situ effectiveness of these essential oils, alone or in combination with other antimicrobial compounds, should be further explored.

Novel Functional Grape Juices Fortified with Free or Immobilized Lacticaseibacillus rhamnosus OLXAL-1.

During the last decade, a rising interest in novel functional products containing probiotic microorganisms has been witnessed. As food processing and storage usually lead to a reduction of cell viability, freeze-dried cultures and immobilization are usually recommended in order to maintain adequate loads and deliver health benefits. In this study, freeze-dried (free and immobilized on apple pieces) Lacticaseibacillus rhamnosus OLXAL-1 cells were used to fortify grape juice. Juice storage at ambient temperature resulted in significantly higher (>7 log cfu/g) levels of immobilized L. rhamnosus cells compared to free cells after 4 days. On the other hand, refrigerated storage resulted in cell loads > 7 log cfu/g for both free and immobilized cells for up to 10 days, achieving populations > 109 cfu per share, with no spoilage noticed. The possible resistance of the novel fortified juice products to microbial spoilage (after deliberate spiking with Saccharomyces cerevisiae or Aspergillus niger) was also investigated. Significant growth limitation of both food-spoilage microorganisms was observed (both at 20 and 4 °C) when immobilized cells were contained compared to the unfortified juice. Keynote volatile compounds derived from the juice and the immobilization carrier were detected in all products by HS-SPME GC/MS analysis. PCA revealed that both the nature of the freeze-dried cells (free or immobilized), as well as storage temperature affected significantly the content of minor volatiles detected and resulted in significant differences in the total volatile concentration. Juices with freeze-dried immobilized cells were distinguished by the tasters and perceived as highly novel. Notably, all fortified juice products were accepted during the preliminary sensory evaluation.

Minimum Inhibitory Concentration (MIC) of Propionic Acid, Sorbic Acid, and Benzoic Acid against Food Spoilage Microorganisms in Animal Products to Use MIC as Threshold for Natural Preservative Production.

Some preservatives are naturally contained in raw food materials, while in some cases may have been introduced in food by careless handling or fermentation. However, it is difficult to distinguish between intentionally added preservatives and the preservatives naturally produced in food. The objective of this study was to evaluate the minimum inhibitory concentration (MIC) of propionic acid, sorbic acid, and benzoic acid for inhibiting food spoilage microorganisms in animal products, which can be useful in determining if the preservatives are natural or not. The broth microdilution method was used to determine the MIC of preservatives for 57 microorganisms. Five bacteria that were the most sensitive to propionic acid, benzoic acid, and sorbic acid were inoculated in unprocessed and processed animal products. A hundred microliters of the preservatives were then spiked in samples. After storage, the cells were counted to determine the MIC of the preservatives. The MIC of the preservatives in animal products ranged from 100 to 1,500 ppm for propionic acid, from 100 to >1,500 ppm for benzoic acid, and from 100 to >1,200 ppm for sorbic acid. Thus, if the concentrations of preservatives are below the MIC, the preservatives may not be added intentionally. Therefore, the MIC result will be useful in determining if preservatives are added intentionally in food.

Performance of UV-LED and UV-C treatments for the inactivation of Escherichia coli ATCC 25922 in food model solutions: Influence of optical and physical sample characteristics

Shortwave ultraviolet light (UV-C) and ultraviolet light-emitting diodes (UV-LEDs) are emergent technologies to inactivate pathogenic and spoilage microorganisms in food. However, the effectiveness of these technologies is influenced by the optical properties of the treated food. This work aimed to evaluate the effect of the optical properties of nine model food solutions on the efficacy of UV-C (at 255 nm) and UV-LEDs (at 255, 265 or 280 nm) to inactivate E. coli ATCC 25922. Model solutions were formulated with saccharose (SC), tartrazine (TT) and xanthan gum (XG), exposed from 0 to 50 min. The microbial population was reduced after 15 min of UV-C and UV-LED treatment by >6 log CFU/mL for water and TT, and by UV-C for SC, XG, TT + SC, and (XG + TT + SC) m solutions. The inactivation data were correlated using three different models. Colored compound (TT) showed 60% degradation by UV-C compared to 3% by UV-LED at 50 min. Industrial relevanceNon-thermal treatments such as those based on ultraviolet light, UV-C, and UV-LEDs could have high industrial relevance because of their simplicity of operation and reduced by-product formation, being a friendly alternative for food processing. Understanding the effect of different optical and physicochemical properties of liquid food to be treated by UV-based technologies is mandatory for the equipment's efficient design and operation. Furthermore, the proper selection of processing conditions, such as delivered dose and processing time, allows for obtaining safe and high-quality products.

Antibacterial and Antibiofilm Efficacy of Thyme (Thymus vulgaris L.) Essential Oil against Foodborne Illness Pathogens, Salmonella enterica subsp. enterica Serovar Typhimurium and Bacillus cereus.

Nowadays, the wide spread of foodborne illness and the growing concerns about the use of synthetic food additives have shifted the focus of researchers towards essential oils (EOs) as possible antimicrobials and preservatives of natural origin. Thanks to their antimicrobial properties against pathogenic and food spoilage microorganisms, EOs have shown good potential for use as alternative food additives, also to counteract biofilm-forming bacterial strains, the spread of which is considered to be among the main causes of the increase in foodborne illness outbreaks. In this context, the aim of this study has been to define the antibacterial and antibiofilm profile of thyme (Thymus vulgaris L.) essential oil (TEO) against widespread foodborne pathogens, Salmonella enterica subsp. enterica serovar Typhimurium and Bacillus cereus. TEO chemical composition was analyzed through gas chromatography-mass spectrometry (GC-MS). Preliminary in vitro antibacterial tests allowed to qualitatively verify TEO efficacy against the tested foodborne pathogens. The subsequent determination of minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values allowed to quantitatively define the bacteriostatic and bactericidal effects of TEO. To evaluate the ability of essential oils to inhibit biofilm formation, a microplate assay was performed for the bacterial biofilm biomass measurement. Results suggest that TEO, rich in bioactive compounds, is able to inhibit the growth of tested foodborne bacteria. In addition, the highlighted in vitro anti-biofilm properties of TEO suggest the use of this natural agent as a promising food preservative to counteract biofilm-related infections in the food industry.

English

Current trends have suggested that the continuous use of chemical additives has carcinogenic effects on consumers. This has instigated the research into more organic ingredients such as plant parts which could serve as potential replacement for these additives in food. This study was therefore conducted to compare the proximate and mineral compositions of the powder of cinnamon bark and clove buds collected from Cape Coast-Ghana, and the effects of their extracts on the growth of selected food spoilage micro-organisms. The proximate analysis revealed both cinnamon and clove as rich carbohydrate sources (61.63 and 36.02%, respectively) with protein as their least components (3.44%). Mineral analysis of the samples revealed potassium as predominant in both cinnamon and clove powder (714.8 and 1296.2 mg/100 g) as both samples were found to be very low in magnesium (0.16 and 0.27 mg/100 g, respectively). The Agar well diffusion method was used to ascertain the inhibitory activity of cinnamon and clove oils on some common food spoilage microorganisms. The analysis revealed cinnamon as potent against Escherichia coli and Salmonella Typhi while clove showed a significant inhibitory activity against Staphylococcus aureus, Pseudomonas aeruginosa and Shigella. In conclusion, the powder of cinnamon bark and clove buds could serve as good carbohydrate and potassium supplements in food while they contribute to increased shelf-life via inhibiting food-borne bacteria. &nbsp; Key words: Proximate, cinnamaldehyde, eugenol, spices, palatability.

Bacteriocin production enhancing mechanism of Lactiplantibacillus paraplantarum RX-8 response to Wickerhamomyces anomalus Y-5 by transcriptomic and proteomic analyses.

Plantaricin is a kind of bacteriocin with broad-spectrum antibacterial activity on several food pathogens and spoilage microorganisms, showing potential in biopreservation applications. However, the low yield of plantaricin limits its industrialization. In this study, it was found that the co-culture of Wickerhamomyces anomalus Y-5 and Lactiplantibacillus paraplantarum RX-8 could enhance plantaricin production. To investigate the response of L. paraplantarum RX-8 facing W. anomalus Y-5 and understand the mechanisms activated when increasing plantaricin yield, comparative transcriptomic and proteomic analyses of L. paraplantarum RX-8 were performed in mono-culture and co-culture. The results showed that different genes and proteins in the phosphotransferase system (PTS) were improved and enhanced the uptake of certain sugars; the key enzyme activity in glycolysis was increased with the promotion of energy production; arginine biosynthesis was downregulated to increase glutamate mechanism and then promoted plantaricin yield; and the expression of several genes/proteins related to purine metabolism was downregulated and those related to pyrimidine metabolism was upregulated. Meanwhile, the increase of plantaricin synthesis by upregulation of plnABCDEF cluster expression under co-culture indicated that the PlnA-mediated quorum sensing (QS) system took part in the response mechanism of L. paraplantarum RX-8. However, the absence of AI-2 did not influence the inducing effect on plantaricin production. Mannose, galactose, and glutamate were critical metabolites and significantly simulate plantaricin production (p < 0.05). In summary, the findings provided new insights into the interaction between bacteriocin-inducing and bacteriocin-producing microorganisms, which may serve as a basis for further research into the detailed mechanism.