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1.
Crit Rev Biotechnol ; : 1-20, 2024 Jul 07.
Article in English | MEDLINE | ID: mdl-38973014

ABSTRACT

D-allulose, an epimer of D-fructose at C-3 position, is a low-calorie rare sugar with favorable physiochemical properties and special physiological functions, which displays promising perspectives in the food and pharmaceutical industries. Currently, D-allulose is extremely sparse in nature and is predominantly biosynthesized through the isomerization of D-fructose by D-allulose 3-epimerase (DAEase). In recent years, D-allulose 3-epimerase as the key biocatalyst for D-allulose production has received increasing interest. The current review begins by providing a summary of D-allulose regarding its characteristics and applications, as well as different synthesis pathways dominated by biotransformation. Then, the research advances of D-allulose 3-epimerase are systematically reviewed, focusing on heterologous expression and biochemical characterization, crystal structure and molecular modification, and application in D-allulose production. Concerning the constraint of low yield of DAEase for industrial application, this review addresses the various attempts made to promote the production of DAEase in different expression systems. Also, various strategies have been adopted to improve its thermotolerance and catalytic activity, which is mainly based on the structure-function relationship of DAEase. The application of DAEase in D-allulose biosynthesis from D-fructose or low-cost feedstocks through single- or multi-enzymatic cascade reaction has been discussed. Finally, the prospects for related research of D-allulose 3-epimerase are also proposed, facilitating the industrialization of DAEase and more efficient and economical bioproduction of D-allulose.

2.
Food Res Int ; 175: 113734, 2024 Jan.
Article in English | MEDLINE | ID: mdl-38129045

ABSTRACT

Shrimp, renowned for its exceptional nutritional value, holds a pivotal position within the realm of aquatic products. The supplementation of extra oxygen to shrimp throughout the entire supply chain has found application within the commercial seafood market. In this study, a dual-platform metabolic analysis, coupled with multivariate data analysis, was employed to discern the impact of supplementary oxygen. Furthermore, this approach facilitated the construction of the post-mortem metabolic profile of shrimp during cold storage. A noticeable decrease of alcohols, ketones and carbohydrates which are related to the energy metabolism in shrimp has been found during cold storage, compared to the fresh shrimp. The degradation of nutritional amino acids was alleviated in shrimp after 4 h of extra oxygen supplement. Furthermore, a higher concentration of identified fatty acids, integral to lipid metabolism and functioning as flavor compounds was observed in shrimp subsequent to oxygen supplementation. Therefore, the additional oxygen supplementation exerted influence on multiple metabolic pathways, including nitrogen metabolism, amino acid and peptide metabolism, nucleotide metabolism, carbohydrate metabolism, and lipid metabolism. This study has constructed a comprehensive post-mortem metabolic profile of shrimp during cold storage, thereby establishing a theoretical foundation for the utilization of oxygen supplements in the preservation of seafood.


Subject(s)
Oxygen , Seafood , Seafood/analysis , Cryopreservation , Metabolome , Energy Metabolism
3.
Int J Food Microbiol ; 407: 110437, 2023 Dec 16.
Article in English | MEDLINE | ID: mdl-37826883

ABSTRACT

The present study investigated the effect of fish gelatin/chitosan-based (FG/CS-based) films incorporated with lemon essential oil (LEO) on grass carp fillets in terms of moisture status, total volatile basic nitrogen (TVB-N), and microbial community succession during chilled (4 °C) and iced (0 °C) storage. Low-field nuclear magnetic resonance (LF-NMR) revealed that the active films remarkably inhibited moisture transformation from being the immobilized to free water in grass carp fillets, accompanied with the reduced T22 relaxation time. Besides, magnetic resonance imaging (MRI) detected a higher density of proton in the treated fish samples, indicating that the active films could improve the water-holding capacity of fish samples. Moreover, high-throughput 16S rRNA sequencing suggested that the FG/CS-based films loaded with LEO efficiently decreased the relative abundance of the bacterial genera Shewanella and Aeromonas in grass carp fillets, with minimal accumulation of TVB-N during storage. Additionally, the low storage temperature (0 °C) could further enhance the preservative effect of the active films on the fish samples, which together prolonged their shelf-life to 18 days. Overall, the combination of the active films and iced storage could provide a promising strategy to preserve grass carp fillets.


Subject(s)
Carps , Chitosan , Oils, Volatile , Animals , Oils, Volatile/pharmacology , Chitosan/pharmacology , Gelatin , RNA, Ribosomal, 16S/genetics , Water , Food Storage/methods
4.
Food Res Int ; 172: 113162, 2023 10.
Article in English | MEDLINE | ID: mdl-37689917

ABSTRACT

Cronobacter sakazakii, an opportunistic bacterium, has raised a serious outbreak in powdered infant formula recent years. In this work, four sanitizing strategies used during infant formula processing, including chlorine, quaternary ammonium chloride (QAC), 60 °C heating, and malic acid (MA), were utilized against C. sakazakii among planktonic, air-dried (A), and air-dried & washed (AW) state, followed by an exploration of the metabolic responses induced by these treatments via a dual-platform metabolomics analysis with the ultra-high performance liquid chromatography-mass spectrometry and nuclear magnetic resonance. In the planktonic state, MA was the most effective in inhibiting bacterial growth, followed by chlorine, QAC, and 60 °C heating. Under A state, the efficacy of heating improved considerably, compared to that in the planktonic state, and remained unaltered under AW state. Chlorine and QAC were ineffective to control bacterial growth under A state, but their efficacy rose under AW state. Furthermore, the metabolomic analysis revealed chlorine induces amino acids catabolism, membrane lysis, and depression in carbohydrate and nucleotide metabolism in both planktonic and AW states, while the initiation of antioxidation mechanism was only found under AW state. Although the metabolic change caused by QAC in the planktonic state was similar to chlorine, the accumulation of osmoprotectant and membrane phospholipids within the AW cells reflected the effort to restore intracellular homeostasis upon QAC. Heating was characterized by considerable amino acid anabolism, along with mildly perturbed carbohydrate and nucleotide metabolism for heat shock protein preparation in both states. Lastly, MA promoted amino acid-dependent acid resistance under the planktonic state, and the regulation of antioxidation and osmoprotection under AW state. The metabolomics study elucidated the intracellular perturbation induced by common sanitizing, as well as the bacterial response, which provides insights for novel sanitization development.


Subject(s)
Cronobacter sakazakii , Humans , Infant , Chlorine , Infant Formula , Metabolomics , Chlorides , Amino Acids , Antioxidants , Nucleotides
5.
Curr Res Food Sci ; 7: 100573, 2023.
Article in English | MEDLINE | ID: mdl-37650007

ABSTRACT

Near-infrared spectroscopy (NIRS) presents great potential in the identification of food adulteration due to its advantages of nondestructive, simple, and easy to operate. In this paper, a method based on NIRS and chemometrics was proposed to predict the content of common buckwheat (Fagopyrum esculentum Moench) flour in Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn) flour. Partial least squares regression (PLSR) and support vector regression (SVR) models were used to analyze the spectrum data of adulterated samples and predict the adulteration level. Various preprocessing methods, parameter-optimization methods, and competitive adaptive reweighted sampling (CARS) wavelength-selection methods were used to optimize the model prediction accuracy. The results of PLSR and SVR modeling for predicting of Tartary buckwheat adulteration content were satisfactory, and the correlation coefficients of the optimum identification models were above 0.99. In conclusion, the combinations of NIRS and chemometrics indicated excellent predictive performance and applicability to analyze the adulteration of common buckwheat flour in Tartary buckwheat flour. This work provides a promising method to identify the adulteration of Tartary buckwheat flour and results obtained can give theoretical and data support for adulteration identification of agro-products.

6.
Food Res Int ; 171: 113084, 2023 09.
Article in English | MEDLINE | ID: mdl-37330837

ABSTRACT

Facing the increasing occurrence of "big six" Escherichia coli outbreaks linked to fresh produce, chlorine-based sanitisers are widely used for fresh produce decontamination in recent years. However, latest finding that chlorine may induce E. coli cells into a viable not nonculturable (VBNC) state is bringing a new challenge to the fresh produce industry. VBNC cells are undetectable by the plate count test, and yet they retain pathogenicity and are more antibiotic-resistant than culturable cells. As a result, their eradication is critical to ensure the safety of fresh produce. Understanding VBNC cells at the metabolic level may provide a breakthrough for their eradication. Therefore, this study was carried out to collect the VBNC pathogenic E. coli (O26:H11, O121:H19, and O157:H7) cells from chlorine-treated pea sprouts and characterise them using NMR-based metabolomics. From the globally increased metabolite contents detected in the VBNC E. coli cells as compared to the culturable cells, mechanisms underlying E. coli's VBNC induction were elucidated. These include rendering the energy generation scheme to become more compatible with the lowered energy needs, disaggregating protein aggregates to release amino acids for osmoprotection and later resuscitation, as well as increasing cAMP content to downregulate RpoS. These identified metabolic characteristics can inspire future development of targeted measures for VBNC E. coli cell inhibition. Our methods can also be applied to other pathogens to help lower the risk of overall foodborne diseases.


Subject(s)
Chlorine , Escherichia coli O157 , Chlorine/pharmacology , Virulence , Metabolome
7.
Front Microbiol ; 14: 1181588, 2023.
Article in English | MEDLINE | ID: mdl-37138594

ABSTRACT

Sufu, a traditional Chinese fermented food, is famous for its unique flavor, especially umami. However, the formation mechanism of its umami peptides is still unclear. Here, we investigated the dynamic change of both umami peptides and microbial communities during sufu production. Based on peptidomic analysis, 9081 key differential peptides were identified, which mainly involved in amino acid transport and metabolism, peptidase activity and hydrolase activity. Twenty-six high-quality umami peptides with ascending trend were recognized by machine learning methods and Fuzzy c-means clustering. Then, through correlation analysis, five bacterial species (Enterococcus italicus, Leuconostoc citreum, L. mesenteroides, L. pseudomesenteroides, Tetragenococcus halophilus) and two fungi species (Cladosporium colombiae, Hannaella oryzae) were identified to be the core functional microorganisms for umami peptides formation. Functional annotation of five lactic acid bacteria indicated their important functions to be carbohydrate metabolism, amino acid metabolism and nucleotide metabolism, which proved their umami peptides production ability. Overall, our results enhanced the understanding of microbial communities and the formation mechanism of umami peptides in sufu, providing novel insights for quality control and flavor improvement of tofu products.

8.
Food Chem X ; 18: 100673, 2023 Jun 30.
Article in English | MEDLINE | ID: mdl-37091513

ABSTRACT

Gelatin emulsion was an important process for preparing gelatin films. A gelatin film with water resistance and ductility could be prepared using gelatin emulsion, whereas the prepared gelatin film has several defects (e.g., low tensile strength and poor thermal stability). This study aimed to modify gelatin emulsion through ultrasonic treatment, then gelatin film was prepared by the modified gelatin emulsion. The results showed that: under the condition of ultrasonic treatment for 12 min at 400 w, zeta potential and viscosity of gelatin emulsion were the largest; thickness, water vapor permeability (WVP) and water solubility (WS) of corresponding gelatin film were the lowest, and the tensile strength (TS), elongation at break (EAB), denaturation temperature (Tm) and enthalpy value (ΔH) of corresponding gelatin film were the highest. The above result suggested that ultrasonic treatment can be used to prepare a gelatin film with better quality by regulating the properties of gelatin emulsion, and a certain correlation was found between the properties of gelatin emulsion and the properties of gelatin film.

9.
Food Res Int ; 164: 112394, 2023 Feb.
Article in English | MEDLINE | ID: mdl-36737976

ABSTRACT

The development of nutritional noodles of high quality has become a new hotspot of research in the area of food science. Since wakame is edible seaweed rich in dietary fiber and proteins and rarely found in ordinary noodle, this study investigated the release of metabolites, the texture quality, and the rheological properties of wakame noodle, as well as the mechanism by which extruded wakame flours can influence noodle texture and viscoelasticity through digestion. Basically, nuclear magnetic resonance spectra were applied to identify the 46 metabolites including amino acids, saccharides, fatty acids, and other metabolites. Both PCA and OPLS-DA model showed fit goodness and good predictivity, which were assessed the increasing release of most metabolites. Structural studies discussed the effects on the enhancement of interlinkage with gluten matrix and protein matrix, which were validated via the decreasing instantaneous compliance J0 (1.64 × 10-5 to 0.16 × 10-5 Pa-1). Wakame addition best matched the physiochemical properties of noodle, in terms of chewiness (99.10 vs 122.66 g.mm), gumminess (281.98 vs. 323.44 g), and gel strength (132.65 vs 173.95 kPa•s-1). Beyond the functional characteristics it contributes benefits like reduction of diet-related diabetes. As a consequence, the creation of personalized nutritious, healthy noodles will be an innovative route from a scientific viewpoint and an application standpoint.


Subject(s)
Cooking , Undaria , Triticum/chemistry , Metabolome , Digestion
10.
Crit Rev Food Sci Nutr ; 63(28): 9098-9110, 2023.
Article in English | MEDLINE | ID: mdl-35507474

ABSTRACT

Antibiotic contamination is becoming a prominent global issue. Therefore, sensitive, specific and simple technology is desirable the demand for antibiotics detection. Biosensors based on split aptamer has gradually attracted extensive attention for antibiotic detection due to its higher sensitivity, lower cost, false positive/negative avoidance and flexibility in sensor design. Although many of the reported split aptamers are antibiotics aptamers, the acquisition and mechanism of splitting is still unknow. In this review, six reported split aptamers in antibiotics are outlined, including Enrofloxacin, Kanamycin, Tetracycline, Tobramycin, Neomycin, Streptomycin, which have contributed to promote interest, awareness and thoughts into this emerging research field. The study introduced the pros and cons of split aptamers, summarized the assembly principle of split aptamer and discussed the intermolecular binding of antibiotic-aptamer complexes. In addition, the recent application of split aptamers in antibiotic detection are introduced. Split aptamers have a promising future in the design and development of biosensors for antibiotic detection in food and other field. The development of the antibiotic split aptamer meets many challenges including mechanism discovery, stability improvement and new biosensor development. It is believed that split aptamer could be a powerful molecular probe and plays an important role in aptamer biosensor.


Subject(s)
Aptamers, Nucleotide , Biosensing Techniques , Anti-Bacterial Agents , Aptamers, Nucleotide/chemistry , Molecular Probes
11.
Food Chem ; 403: 134390, 2023 Mar 01.
Article in English | MEDLINE | ID: mdl-36179634

ABSTRACT

This study investigated the gelling mechanisms of plant-based eggs modified with corn starch (CS), glutinous rice starch (GS), or potato starch (PS) at soy protein isolate (SPI)/starch ratios of 10:4, 8:6, and 6:8 (w/w). A plant-based omelet with SPI/PS 8:6 matched the texture (especially cohesiveness (0.75 vs 0.79)) and specific volume (1.28 vs 1.32 cm3/g) of an egg omelet best. This was attributed to greater protein-starch interactions (H-bonding, ionic bonding) that supported its strong structure. SPI/CS 8:6, SPI/GS 8:6, SPI/PS 10:4, and SPI/PS 6:8 demonstrated more ruptured granules and formed weaker gels. These proposed models were verified by nuclear magnetic resonance (NMR)-based metabolomics, where the stronger SPI/PS 8:6 gel released less metabolites after in vitro digestion. Through understanding different roles of starch in plant-based egg systems, this study suggests more potential applications of starch in modifying food properties.


Subject(s)
Soybean Proteins , Starch , Starch/chemistry , Soybean Proteins/chemistry , Gels/chemistry , Eggs
12.
Food Chem ; 404(Pt A): 134616, 2023 Mar 15.
Article in English | MEDLINE | ID: mdl-36444043

ABSTRACT

Shewanella baltica has a high spoilage ability to decompose nutrients in fish. To investigate the role of S. baltica in fish protein and flavour during spoilage, the texture, rheology, protein patterns and volatile compounds of golden pomfret inoculated with S. baltica during 10-day storage were tested. During storage, S. baltica reduced the hardness of fish sticks by 29.73-49.24 %. Compared to the control (G0': 20.27 ± 2.15 kPa), inoculated samples showed lower moduli (G0': 16.71 ± 0.82-17.50 ± 1.80 kPa). Their myosin heavy chains, myosin-binding protein C and actin were decomposed into smaller proteins, which was validated by the lower intensities of molecules with Mw 160-176 kDa. Furthermore, S. baltica generated volatile spoilage markers, including dimethyl sulfide, 2-methyl-butanal and 3-methyl-butanal. This study reveals the mechanism of fish texture and flavour changes induced by S. baltica, and provides insights into controlling bacterial spoilage of seafood.


Subject(s)
Seafood , Shewanella , Animals , Rheology , Flavoring Agents
13.
Food Chem ; 408: 135232, 2023 May 15.
Article in English | MEDLINE | ID: mdl-36566542

ABSTRACT

Dual-platform metabolomics combined with multivariate data analysis was used to investigate the effects of adding fish gelatin (FGH) at different degrees of hydrolysis (DH) on the growth and metabolic pathways of different species of Lactobacillus in fermented milk. The results showed that the promotion effect of FGH on Lactobacillus was related to the species of probiotics. The corresponding metabolic pathways also changed, with the promotion of Lactobacillus by FGH mainly regulated through amino acid metabolism, lipid metabolism, and nucleotide metabolism pathways. The excess DH inhibited the growth of L. paracasei by adjusting its metabolic state through reducing nucleotide requirements, allocating protein resources, and adopting a stress response. In conclusion, this study revealed the effectiveness of dual-platform metabolomics in explaining the metabolic mechanisms of probiotics, providing theoretical support and a scientific basis for the development of functional fermented foods.


Subject(s)
Lactobacillus , Probiotics , Animals , Lactobacillus/metabolism , Milk/metabolism , Gelatin/metabolism , Hydrolysis , Fermentation
14.
Food Chem ; 404(Pt A): 134580, 2023 Mar 15.
Article in English | MEDLINE | ID: mdl-36257273

ABSTRACT

It has been revealed that slightly acid electrolysed water (SAEW) could delay enzymatic browning and melanin formation in food. In this work, multi-spectroscopic methods and UHPLC-Q-TOF-MS were combined to study the underlying reason. The reversible mixed-type inhibition mode of HOCl (main components in SAEW) was determined. The ground state complex formation quenched the intrinsic fluorescence of polyphenol oxidase (PPO) and it was stable at lower temperature. The PPO conformational change (transformation from α-helix to ß-sheet) induced by SAEW was confirmed by 3D fluorescence and Circular dichroism (CD) spectrum. Moreover, the driving force of the interaction between HOCl and PPO was hydrogen bond, which was validated by the molecular docking result. Besides, the formation of melanin related compounds including dihydroxyphenylalanine (DOPA), dopaquinone, dopachrome, 5,6-dihydroxyindole-2-carboxylic acid (DHICA), 5,6-dihydroxyindole (DHI), and 5,6-indolequinone were significantly inhibited by SAEW treatment. These results demonstrated the potential of SAEW as a PPO inhibitor in the food industry.


Subject(s)
Agaricales , Melanosis , Catechol Oxidase/chemistry , Melanins , Water , Molecular Docking Simulation
15.
Food Chem ; 399: 133959, 2023 Jan 15.
Article in English | MEDLINE | ID: mdl-36001928

ABSTRACT

Advances in understanding the biological effects of dietary flavonoids and flavonoid-rich foods have been reported. Improving knowledge about their beneficial effects, and mechanisms of action, is crucial for better utilization. However, mechanisms responsible for their health benefits are still unclear. Previous research considered has suggested that gut microbiota might be linked to the metabolism of dietary flavonoids. To understand the bioactivities of dietary flavonoids/flavonoid-rich foods better, and the role of microbiota, we explored systematically 1) types of dietary flavonoids and associated health benefits, 2) low bioaccessibilities and metabolic characteristics, 3) gut microbiota role in regulation, and 4) crosstalk between regulation mechanisms. Current challenges and future perspectives were also considered, offering new research directions and identifying trends in the development of flavonoid-rich food products.


Subject(s)
Gastrointestinal Microbiome , Microbiota , Flavonoids/metabolism , Health Promotion , Polyphenols/pharmacology
16.
Food Res Int ; 162(Pt A): 112046, 2022 12.
Article in English | MEDLINE | ID: mdl-36461262

ABSTRACT

The citric acid (CA) and electrolysed water (EW) are considered effectively in inactivating microorganisms. The objective of this study was to explore the bactericidal mechanism of CA combined with EW on Aeromonas spp. in barramundi (Lates calcarifer) by in vitro metabolomics method. This study determined the survival population of three strains of Aeromonas bacteria (strain 1: Aeromonas salmonicida strain A1 (skin); strain 2: A. veronii strain Til2 (gut), and strain 3: A. hydrophila strain B11 (gill)), which were isolated and identified from putrid barramundi treated alone or in combination with 1 % CA and EW (free available chlorine (FAC) 25 mg/L, pH 3.23, oxidation-reduction potential (ORP) 1015 mV). The bactericidal mechanism was investigated by microbiological analysis, nuclear magnetic resonance (NMR), multivariate data analysis, and fluorescence staining analysis. The results showed that the combined treatment significantly reduced the number of Aeromonas bacteria at 1.64-1.69 log CFU/g and extended the shelf life of barramundi fillets. In addition, the combined treatment had a higher effect on the cell membrane integrity of the bacteria. In total, 36 metabolites were identified in the three strains. The undissociated molecules of CA can enter the cytoplasm, resulting in cell damage and inhibiting metabolic pathways. EW could lead to the reduction of metabolic products caused by oxidative stress and acid stress. Under the synergistic stress of CA and EW, the changes of main metabolite contents in the combined treatment group were significantly reduced. After combined treatment, there were 20, 31, and 31 pathways in which carbohydrate metabolism, amino acid metabolism, and energy metabolism were changed considerably. These findings indicated that the bactericidal mechanism of the bactericidal substance might be explained by the interference of the metabolic pathway, which guided post-treatment sanitisation and extended the applicability of the NMR spectrum to specific spoilage organisms (SSO) analysis in fish.


Subject(s)
Aeromonas , Perciformes , Animals , Citric Acid/pharmacology , Water , Anti-Bacterial Agents/pharmacology , Magnetic Resonance Spectroscopy
17.
Food Res Int ; 162(Pt B): 112203, 2022 12.
Article in English | MEDLINE | ID: mdl-36461378

ABSTRACT

With mounting evidence indicating an enhanced thermal resistance of Salmonella at lower aw, the effectiveness of thermal treatment in wheat flour decontamination is challenged. Therefore, this study was carried out to evaluate the thermal resistance of three Salmonella strains, including Enteritidis (ATCC 13076), Typhimurium (ATCC 14028) and Newport (ATCC 6962), at 65 °C in wheat flour at three aw levels (0.33, 0.53 and 0.69), and to explore the mechanisms of the difference in thermal resistance via nuclear magnetic resonance (NMR)-based metabolomics. The results showed that except for the insignificant difference between the reductions of S. Newport at 0.53 and 0.69 flour aw (P > 0.05), a remarkable decreasing trend in Salmonella cell reduction with decreasing flour aw was observed after the 20-min thermal treatment. By comparing the metabolic profiles of each strain recovered from the lower-aw (0.33 or 0.53) flour with that from the aw-0.69 flour, the metabolic differences implying more efficient misfolded protein degradation, higher availability of amino acids as osmoprotectants, larger throughput of energy production by ATP synthase as well as wiser glucose allocation in the metabolic network were suspected to contribute to the strains' enhanced thermal resistance. Overall, the study adds to the evidence for the effect of lower aw in increasing the thermal resistance of Salmonella in wheat flour. Meanwhile, the identified discriminative metabolic pathways may be artificially modified in the future to help ease Salmonella inhibition during cooking or any types of thermal treatments.


Subject(s)
Flour , Water , Triticum , Metabolomics , Salmonella
19.
Food Res Int ; 161: 111844, 2022 11.
Article in English | MEDLINE | ID: mdl-36192974

ABSTRACT

1H NMR combined with multivariate data analysis were applied to investigate the effects of fish gelatin (FG) addition and co-culture of Lactobacillus acidophilus LA-5 (La-5) and Bifidobacterium lactis BB-12 (Bb-12) on the growth and metabolic pathways of the probiotics themselves. The results showed that the addition of FG had no significant effects on the growth of probiotics, but co-culture did promote the growth of probiotics, especially for Bb-12 (up to 2 log CFU/mL). FG addition inhibited amino acids synthesis and TCA cycling in Lacticaseibacillus paracasei subsp. paracasei CASEI 431 (L431) to some extent. However, for the single La-5 strain, these pathways were promoted. As for mixed bacterial cultures, Bb-12 promoted amino acids metabolism, sugar transport and energy metabolism in La-5. These findings suggested that the metabolic profile of probiotic bacteria can be adequately explained by metabolic pathway analysis, which also provides theoretical guidance for the industrialization of functional fermented milk.


Subject(s)
Bifidobacterium animalis , Probiotics , Amino Acids/analysis , Animals , Gelatin , Lactobacillus acidophilus/metabolism , Milk/chemistry , Polysaccharides, Bacterial , Sugars/analysis
20.
Appl Environ Microbiol ; 88(22): e0148222, 2022 11 22.
Article in English | MEDLINE | ID: mdl-36300924

ABSTRACT

In this research, mono- and dual-species biofilms of Escherichia coli (O45:H2 and O121:H19) and Salmonella enterica serovar Typhimurium formed on stainless-steel coupons were treated with 100 mg/L NaClO for 1 min. Confocal laser scanning microscopy (CLSM) was applied to investigate the spatial structural dynamics of mono- and dual-species biofilms, and nuclear magnetic resonance (NMR) spectroscopy was employed to further investigate their metabolic responses toward chlorine. CLSM results indicated that mixed-species biofilms (total biovolume, 148,000 to 167,000 µm3) stimulated the growth of biomass 2 to 6 times that of single-species biofilms. Upon chlorine treatment, E. coli O45 and S. Typhimurium achieved less reduction (P < 0.05) when coexisting in mixed biofilms (0.70 and 1.17 log CFU/coupon reductions, respectively) compared with their corresponding single-species biofilms (1.97 and 2.01 log CFU/coupon reductions, respectively), while for E. coli O121, more reduction (P < 0.05) was achieved in a mixed biofilm (1.37 log CFU/coupon reductions) compared with its single-species biofilm (0.59 log CFU/coupon reductions). Moreover, NMR results suggested that the increase of putrescine (antioxidation regulator) and the decrease of glucose (enhanced glycolysis for energy replenishment) might contribute to the improved chlorine tolerance in mixed biofilms. Overall, dual-species biofilms promoted biofilm growth and their chlorine tolerance. This study improved our knowledge of the metabolic difference of single- and mixed-species biofilms of E. coli and Salmonella to chlorine sanitization and raised an urgency to investigate the effectiveness of common disinfectants against multispecies consortia. IMPORTANCE Outbreaks of Escherichia coli and Salmonella in food might be associated with the cross-contamination of biofilms on food-contact surfaces. The knowledge of the sanitization of mono-species biofilm on the food-contact surface is well established, while mixed-species biofilm occurs more naturally, which could profoundly affect the efficacy of sanitizer. Therefore, this research aims to evaluate the efficacy of using chlorine against single- and dual-species biofilms of E. coli and Salmonella along with the underlying bacterial metabolic responses. The responses of a mixed biofilm of E. coli and Salmonella to chlorine sanitization were clarified, providing insights to develop a targeted and green sanitization strategy against specific pathogens by perturbing their most susceptible metabolism pathway without sanitizer residue.


Subject(s)
Disinfectants , Escherichia coli O157 , Chlorine/pharmacology , Food Microbiology , Colony Count, Microbial , Biofilms , Stainless Steel , Disinfectants/pharmacology , Salmonella typhimurium/physiology
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