Antimicrobial activity of potassium hydroxide and lauric acid against microorganisms associated with poultry processing

Insight into the differences in meat quality among three breeds of sheep on the Qinghai-Tibetan plateau from the perspective of metabolomics and rumen microbiota

Mutton is one of the most popular meats among the general public due to its high nutritional value. This study evaluated the differences in meat quality among Chaka (CK), Black Tibetan (BT) and Oula (OL) sheep and investigated the metabolic mechanisms affecting meat quality using targeted and untargeted metabolomics and 16S rRNA. The results showed that the meat quality of CK sheep was superior to that of BT and OL sheep in terms of meat color, muscle fiber characteristics and nutritional quality. Pseudobutyrivibrio, Alloprevotella, Methanobrevibacter, unidentified_Christensenellaceae, and unidentified_Bacteroidales were key microbes involved in regulating meat color, muscle fiber characteristics, amino acid and fatty acid content. Protein digestion/absorption, pentose phosphate metabolism, carbon metabolism, and glyoxylate and dicarboxylate metabolism were important metabolic pathways involved in meat quality regulation. Our study is important for the development of sheep breeding strategy and sheep meat industry in Qinghai-Tibetan Plateau.

Production of highly immunogenic and safe Triton X-100 produced bacterial ghost vaccine against Shigella flexneri 2b serotype

BACKGROUND

Bacterial ghost cells (BGCs) are cells were drained of their genetic and cytoplasmic components. This work aimed to develop vaccine candidates against the Shigella flexneri (S. flexneri) 2b serotype using the BGCs approach. For the first time, (S. flexneri) 2b serotype BGCs vaccine was prepared by incubation with Triton X-100 (TX100) for only 12 h. Its safety and immunogenicity were compared to another vaccine produced using a previously used surfactant, namely Tween 80 (TW80). Scanning electron microscopy (SEM), cellular DNA, protein contents measurements, and ghost cell re-cultivation were used to confirm the successful generation of the BGCs. Immunogenicity was assessed through mice's intraperitoneal (IP) immunization followed by infection with S. flexneri ATCC 12022. Finally, histopathological examination was carried out.

RESULTS

Viable colony forming units (CFUs) of S. flexneri were counted from stool samples as well as homogenized colon tissues of the non-immunized challenged group. Immunized mice sera showed a significant increase in serum bactericidal activity of both preparations (TX100 = 40% and TW80 = 56%) compared to the non-immunized challenged group (positive control). The IgG levels of the bacterial ghost-vaccinated groups were four and three times greater for the TX100 and TW80 ghost vaccines, respectively, compared to that of the positive control; both bacterial ghost vaccines (BGVs) were safe and effective, according to the results of the safety check tests and histopathological analysis.

CONCLUSIONS

When comparing the BGVs prepared using TX100 and TW80 methods, the use of TX100 as a new chemical treating agent for BGC production attained robust results in terms of shorter incubation time with the targeted cells and a strong immune response against S. flexneri 2b serotype ATCC 12022 in the IP challenge test. However, a clinical study is needed to confirm the efficacy and total safety of this novel vaccine.

Formulation and Characterization of a Novel Palm-Oil-Based α-Mangostin Nano-Emulsion (PO-AMNE) as an Antimicrobial Endodontic Irrigant: An In Vitro Study

Aim: To formulate and characterize a palm-oil-in-water-based α-Mangostin nano-emulsion (PO-AMNE) endodontic irrigant, in order to evaluate its antibacterial efficacy against Enterococcus faecalis, Staphylococcus epidermidis, and Candida albicans biofilms, as well as its capacity to remove smear layer. Methods: The solubility of α-Mangostin in various oils was determined and selected, surfactants and co-surfactants were used for the nano-emulsion trial. PO-AMNE was prepared and optimized. The MIC was performed, and the antimicrobial efficacy was estimated against biofilms. The optimized 0.2% PO-AMNE irrigant antimicrobial efficacy in a tooth model was done using colony-forming units. The treated teeth were processed by scanning electron microscopic examination for debris and smear layer removal. An Alamar Blue assay was used to evaluate cell viability. The optimization of the PO-AMNE irrigant was performed using Box–Behnken statistical design. Results: The optimized 0.2% PO-AMNE irrigant was found to have a particle size of 340.9 nm with 0.246 PDI of the dispersed droplets, and a zeta potential (mV) of −27.2 ± 0.7 mV. The MIC values showed that 0.2% PO-AMNE (1.22 ± 0.02) were comparable to 2% CHX (1.33 ± 0.01), and 3.25% NaOCl (2.2 ± 0.09) had the least inhibition for E. faecalis. NaOCl (3.25%) showed the maximum inhibition of S. epidermidis (0.26 ± 0.05), whereas 0.2% PO-AMNE (1.25 ± 0.0) was comparable to 2% CHX (1.86 ± 0.07). For C. albicans, 2% CHX (8.12 ± 0.12) showed the least inhibition as compared to 0.2% PO-AMNE (1.23 ± 0.02) and 3.25% NaOCl (0.59 ± 0.02). The 0.2% PO-AMNE irrigant was then evaluated for its antimicrobial efficacy against the three biofilms, using colony-forming units. The 0.2% PO-AMNE was comparable to both 3.25% NaOCl and 2% CHX in inhibiting the growth of biofilms. The 0.2% PO-AMNE and 17% EDTA eliminated the smear layer with the lowest mean scores (p < 0.001). Finally, 0.2% PO-AMNE was shown to be biocompatible when compared to 17% EDTA, 3.25% NaOCl, and 2% CHX in immortalized oral keratinocyte cells. Conclusion: Overall, the formulated 0.2% PO-AMNE irrigant was an effective antimicrobial and biocompatible which could combat endodontic-infection-related polymicrobial biofilms.

Preparation of Human Milk Fat Substitutes: A Review

Human milk is generally regarded as the best choice for infant feeding. Human milk fat (HMF) is one of the most complex natural lipids, with a unique fatty acid composition and distribution and complex lipid composition. Lipid intake in infants not only affects their energy intake but also affects their metabolic mode and overall development. Infant formula is the best substitute for human milk when breastfeeding is not possible. As the main energy source in infant formula, human milk fat substitutes (HMFSs) should have a composition similar to that of HMF in order to meet the nutritional needs of infant growth and development. At present, HMFS preparation mainly focuses on the simulation of fatty acid composition, the application of structured lipids and the addition of milk fat globule membrane (MFGM) supplements. This paper first reviews the composition and structure of HMF, and then the preparation development of structured lipids and MFGM supplements are summarized. Additionally, the evaluation and regulation of HMFSs in infant formula are also presented.

A systematic review and meta-analysis of the efficacy of processing stages and interventions for controlling Campylobacter contamination during broiler chicken processing

Systematic review and meta-analysis were conducted to quantify the effects of processing stages and interventions on the prevalence and concentration of Campylobacter on broiler carcasses. To comprehensively capture relevant evidence, six databases were searched using the keywords "Campylobacter" and "broiler chicken." The literature search yielded 10,450 unique citations, and after applying predetermined inclusion and exclusion criteria, 72 and 53 relevant citations were included in meta-analyses for processing stages and interventions, respectively. As the two primary outcomes, log reduction and prevalence changes were estimated for each stage or intervention using a random-effects meta-analysis approach whenever possible. The outcome-level quality assessment was conducted following the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. The analysis revealed that scalding and chilling majorly reduces the prevalence and concentration of Campylobacter. Immersion chilling reduces the concentration regardless of chemical additives, but its effect on prevalence is not conclusive. The effects of carcass washing applications remain uncertain due to the inconsistency and imprecision of both outcomes. Defeathering and evisceration were identified as stages that can increase both prevalence and concentration. Both chemical and physical processing interventions provide limited efficacy in concentration and prevalence reduction. Major limitations of the review were inconsistency and imprecision at the outcome level and reporting issues and data gaps at the study level. The results are expected to inform quantitative microbial risk assessment model development and support evidence-based decision-making.

Antimicrobial efficacy of medium chain fatty acids as root canal irrigants: An in vitro study

BACKGROUND

Enterococcus faecalis and Candida albicans are the microbes that are most resistant to elimination by disinfecting agents and are the causative agents for reinfection of the root canal treated teeth. Medium chain fatty acids (MCFAs), which are the main components of coconut oil, are proven antimicrobial agents. Thus, the aim of this study was to evaluate their antimicrobial efficacy against E. faecalis and C. albicans.

METHODOLOGY

Ninety extracted single-rooted mandibular premolar teeth were decoronated, biomechanically prepared, autoclaved, and divided into three groups (n = 30): Group A (inoculated with E. faecalis), Group B (inoculated with C. albicans), and Group C (control group). Each group was again subdivided into three groups (n = 10) and irrigated with lauric acid (LA), decanoic acid (DA), and octanoic acid, respectively, for 5 min. Paper point samples were taken from canal walls and transferred into Brain Heart Infusion broth and potato dextrose broth and placed in an incubator at 37°C. The appearance of tubidity was checked at 24, 48, 72, and 96 h using direct contact test. The data were then statistically analyzed using the analysis of variance and Tukey honestly significant difference post hoc tests.

RESULTS

Among the three MCFAs, LA showed the maximum inhibitory against E. faecalis at 24 h and the inhibitory activity decreased considerably at 48, 72, and 96 h. DA was the most effective against C. albicans with a maximum inhibition at 48 h. DA also showed significant substantivity at 72 and 96 h.

CONCLUSION

Within the limitations of this study, it can be concluded that MCFAs show promising antimicrobial efficacy against E. faecalis and C. albicans.

A novel protocol for bacterial ghosts' preparation using tween 80

Bacterial ghosts (BGs) can be prepared by both genetic and chemical means. Genetic method include using lysis gene E. Chemical method include incubation with numerous agents for a short time at their minimum inhibitory or minimum growth concentrations (MIC or MGC). The aim of this study is to prepare the BGs with a new protocol via exposing the bacterial cells to tween 80 for an extended period of time followed by sudden reduction of the surrounding pH. Salmonella enterica serovar typhimurium ATCC 13311 was used for this purpose. The cells were incubated in 7% v/v tween 80 solution in Muller-Hinton broth for 24 h at 37 °C then pH was decreased to 3.6 by adding lactic acid for one hour. The bacterial pellets were separated by high speed centrifugation, and then washed three times by half normal saline solution. High quality BGs were visualized by scanning electron microscopy (SEM) revealing punctured cells with intact outer shells and at least one intramembranous tunnel. The absence of vital cells was confirmed by subculturing. The release of respective amounts of proteins and DNA is another evidence of ghost's production. In addition, the integrity of cells was proved by visualization of Gram-stained cells using light microscopy. In conclusion, this new protocol is simple, economic and feasible for BGs preparation.

Lauric Acid Is an Inhibitor of Clostridium difficile Growth in Vitro and Reduces Inflammation in a Mouse Infection Model

Clostridium difficile is a Gram-positive, spore-forming anaerobic human gastrointestinal pathogen. C. difficile infection (CDI) is a major health concern worldwide, with symptoms ranging from diarrhea to pseudomembranous colitis, toxic megacolon, sepsis, and death. CDI onset and progression are mostly caused by intestinal dysbiosis and exposure to C. difficile spores. Current treatment strategies include antibiotics; however, antibiotic use is often associated with high recurrence rates and an increased risk of antibiotic resistance. Medium-chain fatty acids (MCFAs) have been revealed to inhibit the growth of multiple human bacterial pathogens. Components of coconut oil, which include lauric acid, have been revealed to inhibit C. difficile growth in vitro. In this study, we demonstrated that lauric acid exhibits potent antimicrobial activities against multiple toxigenic C. difficile isolates in vitro. The inhibitory effect of lauric acid is partly due to reactive oxygen species (ROS) generation and cell membrane damage. The administration of lauric acid considerably reduced biofilm formation and preformed biofilms in a dose-dependent manner. Importantly, in a mouse infection model, lauric acid pretreatment reduced CDI symptoms and proinflammatory cytokine production. Our combined results suggest that the naturally occurring MCFA lauric acid is a novel C. difficile inhibitor and is useful in the development of an alternative or adjunctive treatment for CDI.

Bacterial flora of processed broiler chicken skin after successive washings in mixtures of potassium hydroxide and lauric acid

Changes in the size of populations of different groups of bacteria composing the normal flora of processed broiler skin were examined after each of five consecutive washings in mixtures of potassium hydroxide (KOH) and lauric acid (LA). Portions of skin from commercially processed broiler carcasses were washed in distilled water (control) or in mixtures of 0.25% KOH-0.5% LA or 0.5% KOH-1% LA by using a stomacher laboratory blender to agitate the skin in the solutions. After each wash, skin was transferred to fresh solutions, and washing was repeated to provide samples washed one to five times in each solution. Bacteria in rinsates of the washed skin were enumerated on plate count (PC) agar, Staphylococcus (STA) agar, Levine eosin methylene blue (EMB) agar, lactic acid bacteria (LAB) agar, and Perfringens (PER) agar with TSC supplement. Selected isolates recovered on each medium were identified. Overall, no significant differences were observed in numbers of bacteria recovered on PC, STA, or EMB agars from skin after repeated washing in water, but there were significant reductions in the number of bacteria recovered on LAB and PER agars. Repeated washing of skin in 0.25% KOH-0.5% LA or 0.5% KOH-1% LA generally produced significant reductions in the number of bacteria recovered on all media. Furthermore, no bacteria were recovered on PER agar from skin washed five times in 0.25% KOH-0.5% LA. Likewise, no bacteria were recovered on EMB or LAB agars from skin washed three or more times in 0.5% KOH-1% LA or on PER agar from skin washed four or five times in this solution. Staphylococcus spp. were identified as the skin isolates with the highest degree of resistance to the bactericidal activity of KOH-LA. Findings indicate that although bacteria may be continually shed from poultry skin after repeated washings, bactericidal surfactants can be used to remove and kill several types of bacteria found on the surface of the skin of processed broilers.