Plate Count Research Articles

Microbial Succession and Effect of Fermentation on the Proximate Composition of Sweet Potato Tubers, Leaves and Vines

This study was aimed at determining the effect of fermentation on the proximate composition of sweet potato tubers, leaves and vines. The study involved the spontaneous fermentation of the substrates for five days (120h). Physico-chemical properties and microbial counts were determined during the fermentation period. Lactic acid bacteria and yeasts were isolated and characterized. Proximate composition of the substrates were determined at the end of the fermentation period. The results obtained show that the aerobic plate counts range from 6.80x105±1.00x105- 8.40x106±1.00x105CFU/g, lactic acid bacteria count range from 1.70x105±1.30x105- 1.60x107±6.00x106 CFU/g and fungal count range from 2.50x105±8.00x104- 7.75x106±5.50x105 CFU/g. The counts were significantly different in most cases (p≤0.05). The lactic acid bacteria and yeast isolated and identified from the study include Lactobacillus plantarum, L. buchneri, L. delbrueckii, L. brevis, L. lactis, L. fructovorans, L. colloides, L. pentosus, Leuconostoc mesenteroides, Weisella confusa, Candida krusei, C. utilis, C. ciferii, C. spherical, C. rugosa, C. zeylanoides, C. guilliermondii, C. lipolytica, C. tropicalis, C. boidinii, Saccharomyces cerevisiae, Rhodoturulaminuta, R. glutinis, Kodamaeaohmeri, Kloekerasp. The results of the proximate composition show that there was increase in both Nitrogen free extract and metabolisable energy and decrease in protein content and ash content after fermentation. Findings from this study imply that fermentation of these substrates is characterized by a wide variety of lactic acid bacteria and yeasts with positive effect on the proximate composition of the substrates.

Sustainable and efficient monitoring of tryptophan and tyrosine serum levels: a green HPTLC method as a biomarker for type 2 diabetes

In recent years, there has been considerable interest in using amino acids like tryptophan (Trp) and tyrosine (Tyr) as biomarkers for various diseases, including type 2 diabetes mellitus (T2D). In diseases like T2D, the metabolism of Trp and Tyr is altered. The activity of enzymes involved in Trp metabolism increases, leading to a decrease in its serum level. On the other hand, the serum level of Tyr increases due to the suppressed activity of its metabolizing enzymes. These observations suggest that Trp and Tyr metabolism may play a crucial role in the pathophysiology of type 2 diabetes. Our study highlights the potential utility of Trp and Tyr as biomarkers for the early detection, prognosis, and monitoring of this metabolic disorder. Given these observations, we aimed to develop a high-performance thin-layer chromatographic (HPTLC) method that is sensitive, selective, rapid, and environmentally friendly for estimating the concentrations of Trp and Tyr in biological fluids, particularly serum samples. To evaluate the method, we performed analysis using serum samples from controlled and streptozotocin-induced diabetic rats. Our main objective was to develop a method that is sensitive and selective for precisely determining Trp and Tyr serum levels, which could serve as potential biomarkers for T2D. Fluorescence and absorption modes were employed for densitometry scanning. We assessed the precision and high separation efficiency of the chromatographic system by calculating parameters such as separation and resolution factors, number of theoretical plates, and height equivalent to theoretical plates. To evaluate the environmental impact of our proposed method, we employed the AGREE (Analytical GREEnness metric) and GAPI (Green Analytical Procedure Index) greenness assessment tools. The results confirmed that our method is environmentally friendly and exhibits superior eco-friendliness and greenness compared to other reported methods.Graphical

Antimicrobial Activity of Diffusible Substances Produced by Lactococcus lactis Against Bacillus cereus in a Non-Contact Co-Culture Model

The symptoms of foodborne illness caused by Bacillus cereus often go unreported, complicating the effectiveness of conventional chemical and physical methods used to inhibit its growth in food production. This challenge, combined with the increasing use of lactic acid bacteria (LAB) in the food industry and consumer preference for minimally processed products, prompted this study. The antibacterial activity of diffusible substances produced by Lactococcus lactis ATCC 11454 against Bacillus cereus NC11143 and Escherichia coli K-12 MG1655 was investigated using a non-contact co-culture model utilising deMann Rogosa and Sharpe broth, with glucose as a carbon source. This study employed plate counting and flow cytometry to assess the impact of these substances on bacterial growth and to analyse their composition and antimicrobial efficacy. The co-culture of Lactococcus lactis ATCC 11454 resulted in the production of a stable antimicrobial peptide, which was heat resistant and acid tolerant. Purification was achieved via ammonium sulphate precipitation and preparative HPLC, yielding a peptide with a molecular mass of 3.3 kDa, with daughter ion fractions similar to nisin A. Antimicrobial activity studies demonstrated that the diffusible substances effectively inhibited B. cereus growth over a period of eight days and exhibited bactericidal activity, killing 99% of the B. cereus cells. Additionally, these substances also inhibited Escherichia coli K-12 MG1655 grown under similar conditions. Comparative analysis revealed that in the co-culture assay, L. lactis produced a 50% higher yield of the antimicrobial peptides compared to pure cultures. Similarly, the specific growth rate of L. lactis was four times higher. With respect to protein purification and concentration, ammonium sulphate precipitation coupled with solid phase extraction was most effective in the purification and concentration of the diffusible substances. The findings provide a basis for utilising bacteriocin-producing strains as a preservation method, offering an alternative to traditional chemical and physical control approaches especially for the food industry.

CDC42 enhances phagocytic activity and exhibits antimicrobial functions through the recruitment of IQGAP1 in Apostichopus japonicus

Cell Division Cycle 42 protein (CDC42) is a pivotal member of the Rho family of small GTPases, integral to cell signaling and the regulation of cell polarity. CDC42 is extensively documented to participate in host immunity, particularly in processes such as phagocytosis and cell migration. Nevertheless, the precise mechanisms by which CDC42 affects host-bacteria interactions remain unclear in Echinoderms. In this study, we have isolated and characterized the CDC42 gene from Apostichopus japonicus, referred to as AjCDC42. The complete cDNA sequence of AjCDC42 extends 1282 base pairs, including a typical classical RHO domain, spanning amino acids from 6 to 179. Spatial expression analysis demonstrated that AjCDC42 is ubiquitously expressed across all examined tissues. Following infection with Vibrio splendidus and stimulation with LPS, the protein and mRNA levels of AjCDC42 were significantly upregulated in coelomocytes. Moreover, the knockdown of AjCDC42 significantly decreased V. splendidus-induced phagocytic activity in coelomocytes, leading to a reduced intracellular load of V. splendidus, as evidenced by flow cytometry and bacterial plate counting assays. Mechanistically, AjCDC42 was identified as an interacting partner of IQ Motif Containing GTPase Activating Protein 1 (AjIQGAP1) through the use of co-immunoprecipitation, immunofluorescence, and GST pull-down assays combined with mass spectrometry techniques. Additional functional analyses revealed that the knockdown of AjIQGAP1 similarly decreased the phagocytic activity and the intracellular load of V. splendidus in coelomocytes. Furthermore, we detected that decreased levels of AjCDC42 and AjIQGAP1 impaired cytoskeletal rearrangement and delayed lysosomal clearance of V. splendidus. In summary, our findings underscore the pivotal role of the AjCDC42-AjIQGAP1 axis in regulating coelomocytes phagocytosis in A. japonicus during V. splendidus infection.

Sensitivity analysis of damage extent in naval ship compartments due to internal airborne explosions

The objective of this paper is to identify the design variables of the compartment that are most influential in determining the extent of damage due to in-compartment airborne explosions (INCEX). From a comparison of numerical simulation results using the CONventional Weapons Effects Program (CONWEP) with results from airborne blast experiments, CONWEP generated blast pressures with reasonable accuracy. From a comparison of numerical simulation results using the Horsford-Coulomb and local necking hybrid fracture model (HC-LN model) with results from indentation experiments, HC-LN model accurately predicts steel fractures. The engine compartment was selected for the damage variable sensitivity analyses in terms of the probabilities of being hit, flooded, and incapacitated. When three TNT masses, two stand-off distances, and eight engine room dimensions with six levels of each dimension were considered, more than 10 million INCEX cases were required. The Latin hypercube sampling technique was adopted to reduce the number of INCEX simulations to 5,000. The element-based and image-based methods were applied to evaluate the damage extents. The element-based method underestimated and overestimated the damage area and damage perimeter more than the image-based method, respectively. The most influential design variables on the damage extent were bulkhead thickness and curtain plate height, respectively.

Experimental demonstration of the production of poly(oxymethylene) dimethyl ethers from methanolic formaldehyde solutions in a closed-loop mini-plant

Poly(oxymethylene) dimethyl ethers of chain length 3-5 ( ▪ ) are discussed as synthetic diesel fuels due to their potential to significantly reduce soot emissions while presenting physicochemical properties similar to conventional diesel fuels. A recently developed process to produce ▪ directly from methanol and aqueous formaldehyde is a promising way to avoid expensive intermediates such as trioxane, methylal, or dimethyl ether. The process consists of a reactor, a distillation sequence, and a membrane unit. The first distillation column is particularly challenging due to the reactive character of the separation, the high number of components present, and the limited solubility of formaldehyde. Up to now, the feasibility of this separation has yet to be demonstrated. This work presents closed-loop experiments in a demonstration plant erected at the Campus Straubing of the Technical University of Munich with closing recycle. In the distillation step, ▪ with with very small impurities of around 800 ppm of formaldehyde was obtained. The experimental results were compared with simulations based on a reactive equilibrium stage model. The simulations of the temperature and composition profiles for the majority of the components are in line with the experiments. Although the membrane separation exhibited weaker water selectivity than in previous tests, it was sufficient to overcome distillation boundaries. Additionally, this study assesses the potential for solid precipitation, explores trade-offs in product quality, and discusses overall mass balances of the process, demonstrating the overall feasibility of the process.

Process Intensification in Distillation using HiGee Rotating Packed Bed

For decades, improving the gas-side mass transfer coefficient in rotating packed beds has been a formidable challenge. Distillation, often limited by gas-phase resistance, requires substantial innovation to enhance these coefficients. Rotating packed beds offer a distinct advantage over conventional columns, primarily due to the intense micro-mixing within fluid channels. This micro-mixing significantly boosts mass transfer between phases and facilitates rapid attainment of steady-state conditions, making them a superior choice for processes where gas-side resistance is the bottleneck. The current study emphasis on the mass transfer performance of rotating packed for acetone water system with two different packing materials viz., wire mesh and ceramic beads. Working principle of HiGee, typical flow pattern, modeling equations have been discussed in this paper. The effects of rotational speed, gas flow rates and radial thickness of the packing on mass transfer performance were also investigated. The mass transfer coefficients of the rotating packed bed HiGee were increased with increasing the rotational speed. The Height Equivalent to Theoretical Plates (HETP) of the rotating packed bed used in this study was 5-6 times less than the conventional packed columns. This study contributes to significantly advancing the industrial applications of rotating packed beds.

Monitoring of Animal Products Entering East Kalimantan with Total Plate Count Test

Monitoring of Animal Products Entering East Kalimantan with Total Plate Count Test

Students’ Habits and Identification of Bacteria on Inanimate Surface of Educational Setting

Introduction: Diponegoro Clinic reported 29.1% of students seek infectious diseases treatment. Student habits in the classroom were thought to play roles in the presence of bacteria. Surfaces of inanimate objects in the classroom were potential source for bacteria. The research objectives were analyzing student’s habits and identifying bacteria on the surface of inanimate objects in the classroom. Methods: Four types of samples, including the surfaces of tables, chairs, flips of air conditioners, and floors were taken from 13 faculties at Universitas Diponegoro. Plate count agar media were used to isolate bacterial colonies, and PCR analysis was performed for DNA extraction and amplification. DNA Sanger sequencing techniques were used for genetic bacterial identification. The online questionnaire was used to assess student habits in the classroom. Two hundred students responded. Results and Discussion: Acinetobacter baumannii and Staphylococcus aureus were found in classrooms. These bacteria were associated with respiratory tract infections. This study revealed that 86.5% were between the ages of 17-21, 60.81% were from outside Semarang City, and 88.33% lived in Semarang City. About 60.81% of respondents studied in health sciences. Furthermore, it was reported that 66.67% of respondents were sick in the last few weeks, attended class despite being sick (72.52%), and coughed and sneezed in class (40.99%). Conclusion: Bacteria associated with respiratory tract infection were found. Students' habits in the classroom were potentially caused by the presence of these bacteria. The use of antibacterial agents could reduce the presence of bacteria on inanimate object surfaces.

Medulla Tetrapanacis water extract ameliorates mastitis by suppressing bacterial internalization and inflammation via MAPKs signaling in vitro and in vivo

AbstractMedulla Tetrapanacis (MT) is a commonly used herbal ingredient in soup to promote lactation and management of mastitis among lactating mothers worldwide, particularly in Asian countries. However, scientific evidence to support its usage in the management of mastitis is limited. This study aimed to investigate the effects of MT water extract and its underlying mechanisms in Staphylococcus aureus (SA)–induced mastitis in human mammary epithelial cells (HuMEC) and lipopolysaccharide (LPS)–induced mastitis in lactating Sprague–Dawley (SD) rats. The anti‐inflammatory and antibacterial effects of MT water extract were examined in SA‐infected HuMEC by ELISA and plate counting, respectively. The effects of MT water extract on blood‐milk barrier and the underlying mechanism of action of the MT water extract were also investigated by transendothelial electrical resistance assay and western blot. The effects and mechanisms of MT water extract on alleviating mastitis on SD rats were evaluated using LPS‐induced mastitis rat model. Our results showed that MT water extract could suppress SA‐induced mastitis by reducing SA internalization and growth, protecting blood‐milk barrier integrity, and attenuating release of cytokines (interleukin 6 [IL‐6] and tumor necrosis factor‐alpha [TNF‐α]) in HuEMC. Furthermore, the antibacterial effect might be related to the increase of antimicrobial peptides transcription, and the anti‐inflammatory effect is at least partly mediated by inactivation of p38 and JNK signaling pathways. Finally, our in vivo results showed that MT water extract ameliorated LPS‐induced mastitis in SD rats via suppressing inflammatory cytokine release (TNF‐α, IL‐6, and interleukin‐1 beta), myeloperoxidase, and alleviating pathohistological damage by downregulation of JNK signaling pathway.

The evaluation of bottled water quality compliance association formal and informal retailers in Gauteng municipality. South Africa

The quality of bottled water (BW) can vary based on factors such as handling, processing, transportation, hygiene practices, and the retail shop from which it is purchased. This study aimed to compare the microbiological quality of BW (Heterotrophic plate count (HPC), E.coli, and total coliforms (TC)) purchased from both formal and informal retail shops. The study used a convenience sampling approach and categorized the shops into formal and informal. A total of 117 samples were obtained, with 16 from informal shops and 101 from formal shops. The data was analysed using SPSS version 29, and the water quality compliance was assessed based on SANS 241, 1657, and World Health Organization standards for drinking water. The findings indicated a significant link between compliance with bottled water (BW) standards and the specific shop from which the BW was purchased (p 0.001). These results highlight shop compliance's crucial role in influencing BW's microbiological quality, especially in relation to total coliforms (TC) and E.coli presence. Bottled water obtained from informal shops did not meet the standards, whereas BW from formal shops adhered to the standards for TC and E.coli.

Effectiveness of Ozone Treatment and Packaging Techniques in Preserving Taiwanese Domestic Beef During Refrigerated Storage

This study investigates the efficacy of ozone treatment combined with different packaging methods on the preservation of Taiwanese domestically produced beef during refrigerated storage. The preservation of fresh beef is crucial for ensuring food safety and quality; we do not know whether changing the packaging method can mitigate the negative effects of ozone on meat and even enhance its positive impact. Beef samples were treated with ozone and packaged using the vacuum or PVDC-tray methods, then stored at 4 °C for 7 days. The results show that ozone treatment effectively inhibited microbial (total plate count, Salmonella, and Escherichia coli) growth (p < 0.05). Vacuum packaging maintained lower TBARS values (p < 0.05) and metmyoglobin percentages compared to PVDC-tray packaging (p < 0.05). The L* values of all treatments increased over storage time, with significant differences observed between days 0 and 7. Ozone treatment combined with vacuum packaging demonstrated promising results in inhibiting microbial growth and preserving beef quality during refrigerated storage. These findings contribute to enhancing the safety and shelf life of Taiwanese domestically produced beef, potentially benefiting both producers and consumers.

Fish oil-containing edible films with active film incorporated with extract of Psidium guajava leaves: preparation and characterization of double-layered edible film

The utilization of zein and gum arabic has grown in an attempt to formulate wall materials based on protein–polysaccharide complexes. This mixture provides a versatile delivery system for hydrophilic (guava leaf extract, GLE) or lipophilic (fish oil, FO) bioactive compounds, and it can be used as an edible film-forming polymer. This study was undertaken to characterize FO-containing edible films that were double-layered with a film containing GLE. Modified zein and gum arabic solutions (MG complex) were mixed at a ratio of 1:1.5 (v/v), adjusted to pH 5, added with glycerol (20% of the complex) and FO (5% of the complex), and finally adjusted to pH 5. This was prepared as the bottom/lower layer. The upper/active layer was prepared by mixing MG complex, glycerol, and GLE (1, 3, and 5% w/v of the complex). The total phenolic and flavonoid contents in GLE were 15.81 mg GAE/g extract and 6.99 mg QE/g extract, respectively. The IC50 of the DPPH radical scavenging activity of GLE was 26.86 ppm with antibacterial activity against Bacillus subtilis and Escherichia coli of 9.83 and 12.55 mm. The total plate counts of double-layered films containing GLE were retained below 3 log CFU/g during 28-day storage. The peroxide values of these films were dimmed for no more than 9.08 meq/kg sample on day 28 of storage. Thickness (872.00-971.67 μm), water vapor transmission rate (12.99-17.04 g/m2/day), tensile strength (1.56-2.02 kPa), elongation at break (61.53-75.41%), glass transition (52.74-57.50°C), melting peak (131.59-142.35°C), inhibition against B. subtilis (33.67-40.58 mm), and inhibition against E. coli (2.05-9.04 mm) were obtained by double-layered films. GLE can be successfully incorporated into the active layer of a double-layer film to improve its characteristics while significantly slowing down the microbial contamination and oxidation rate. MG complex and FO can also contribute to the performance of the edible film.

Development of Dietetic Misti Dahi (Indian Yoghurt) Using Natural and Artificial Sweeteners

Dairy based sweetmeats usually contain high sugar with a high calorific value which in turn is linked to various non-communicable diseases. To reduce this high calorie content, sugar can be replaced in part or wholly by non-nutritive artificial sweeteners, as well as natural sweetener like honey. In the present study natural and artificial sweetener sources (honey and sucralose, respectively) were used to replace sucrose in part or completely to develop low calorie fat reduced misti dahi, an Indian yoghurt. Effect of sweeteners on setting time, proximate composition, microbiological quality and calorific value of mistidahi, and sensory quality were analysed as per the standard methods. Protein and total solids (TS) content decreased from 4.22 to 3.96% or 4.39 to 4.23% in honey or sucralose and from 24.20 to 21.99% in honey or 21.57 to 16.70% in sucralose, respectively with increase in honey or sucralose used to replace sucrose in mistidahi, while fat content was variable. Microbiological analysis revealed that with an increase in the content of honey, the total aerobic plate count (TAPC) of mistidahi tended to show an increase, while for sucralose containing samples a decreasing trend in TAPC in mistidahi was noted.

The Nusselt number of a hot sphere levitated by a volatile pool

When placed at the surface of a volatile liquid, a sphere of hot dense non-volatile material remains suspended until it cools sufficiently. The duration of this ‘inverse Leidenfrost’ phenomenon depends on the Nusselt number $Nu$ of the sphere, itself determined by flow in the film of vapour separating particle and liquid. It is shown that provided the Nusselt number is large, it can be calculated numerically using only the Laplace relation and the equations governing the thin film; patching to a solution for the outer thick film is not necessary. This method is demonstrated by using it to determine $Nu$ for a sphere sufficiently small that in the governing equations, the acceleration due to gravity is negligible except where multiplied by the density of the sphere. Numerical results giving $Nu$ as a function of a dimensionless measure of sphere weight are supplemented with analysis showing that, when the weight is of the order of the maximum supportable by surface tension alone, the film consists of a spherical bubble cap bounded by its contact rim. The solutions for these regions are coupled: although the apparent contact angle $\chi$ for the cap is determined within the rim, its value depends on the flow rate arriving from the cap as well as on the additional evaporation from the rim. The latter acts to reduce $\chi$ from the value it would otherwise have, thereby reducing the thickness of the entire cap. For the example treated here, the value of $Nu$ is doubled by this mechanism.

Therapeutic Efficacy of Eucalyptus Oil as Teat Dip in Subclinical Mastitis in Goats

Mastitis, an inflammation of the parenchyma of mammary gland, results in alterations to the chemical and physical composition of milk due to a variety of infectious and non-infectious causes. The present work was conducted in the Department of Veterinary Medicine, College of Veterinary Science and Animal Husbandry, Nanaji Deshmukh Veterinary Science University, Jabalpur, Madhya Pradesh (M.P.). A total of 256 lactating goats irrespective of age, breed, parity and stage of lactation belonging to both organized and unorganized sectors at Jabalpur were screened from “February 2024 to July 2024”. On the basis of modified California mastitis test (MCMT) score, out of 256 lactating goats, 98 goats were found positive for subclinical mastitis with overall occurrence as 38.28% on animal basis and 33.33% on udder halves basis. Therapeutic study on 24 milk samples positive for subclinical mastitis by MCMT was conducted and categorized into four treatment groups (G1, G2, G3 and G4), each group comprised of 6 goats. Six apparently healthy goats were selected as healthy control group (G5). Two different teat dips viz. Eucalyptus oil 98% + DMSO 2% BID for 14 days in groups G1 and G3 and 5% Povidone iodine BID for 14 days in groups G2 and G4 were used as teat dips, respectively. Moreover, goats of groups G3 and G4 were commonly treated with parenteral antibiotic amoxicillin sulbactam @10 mg/kg b.wt. I/M OD for 3 days. Significantly higher values of somatic cell count, standard plate count, pH, freezing point and significantly lower value of lactose were observed in subclinical mastitis affected goats. The mean density and mean water percentage values varied within normal physiological range. On the basis of restoration of milk parameters and standard plate count, the most effective therapy was elicited by Eucalyptus oil 98%+ DMSO 2% as teat dip in combination with antibiotic amoxicillin sulbactam (G3).

Preparation of monolithic silica HPLC columns with truss-structured skeletons and embedded surfactant-templated mesopores

AbstractMonolithic macro/mesoporous silica gels have been prepared via a sol-gel process using triblock copolymer Pluronic P123 (EO20PO70EO20) as a structure-directing agent. In this synthesis, P123 not only induces phase separation to form macroporous structure but also acts as a supramolecular template to form mesopores with precisely controlled shape and size. Obtained was a monolithic silica composed of continuous truss-like columnar skeletons in which cylindrical mesopores are arranged in a 2D-hexagonal symmetry. These monolithic silica gels have extremely high porosity approaching 90% and exhibited high specific surface area and sharp pore size distribution as revealed by N2 sorption measurements. Combinations of the initial composition and the post-gelation treatment on wet gels allowed the control of physical properties of meso- and macropore structures. The monolithic HPLC columns prepared using these silica gels surface-modified by ODS (octadecylsilyl) ligands gave as many as 140,000 theoretical plates/m for the separation of alkylbenzenes in a reversed-phase mode. Very weak dependence of height equivalent to theoretical plate, H, on the mobile phase velocity was also recognized in comparison with conventional particle-packed columns. Graphical Abstract

Pengaruh Level Tepung Jagung Terhadap Kualitas Organoleptik, Oksidasi Lemak Dan Total Bakteri Sui Wu’u Daging Babi Bagian Perut

The purpose of this study was to determine the effect of corn flour levels on organoleptic quality, fat oxidation and total bacteria in the processing of pork belly sui wu'u. This study used a Complete Random Design (RAL) consisting of three treatments and five replicates so that there were 15 experimental units. The pork used were: belly pork including fat and skin as much as 250 g from each test, and the use of cornmeal with different levels in each treatment, namely: 200% (P1), 400% (P2), and 600% (P3). The variables measured were fat oxidation, total bacteria and organoleptic tests including color, aroma, taste and texture. The results of statistical analysis showed that the administration of corn flour with different levels in sui wu'u of abdominal pork showed a real effect (P<0.05) on organoleptic quality and TBA value, but no real effect (P>0.05) on TPC. It was concluded that the higher the level of corn flour given, the higher the organoleptic quality and the decrease in Total Plate Count (TPC). The best level of cornstarch in pork sui wu'u is at the level of 600%. The best organoleptic quality is: color at P3 2.70±1.15% (pale red), the best value of TBA at P2 is 12.81±1.08 mg. Mal/g, and the best value of TPC in P2 is 3.37±3.38 (colony/gr).

Evaluation of the Antibacterial Activity of Antibiotics with different Antibacterial Mechanisms using Electrochemical Signals of Heat‐Treated Escherichia Coli

AbstractElectrochemistry with purines as indicators may be a promising new method for antibiotic activity testing. However, the traditional electrochemical detection method (S‐LSV) requires a long accumulation time for purines and has low signal intensity. High‐temperature treatment of bacterial samples may significantly enhance the signal intensity and speed of detection. However, this process may also impact the structure and metabolism of bacteria. Further research is necessary to determine how electrochemical signals respond to antibiotic antibacterial activity. In this paper, the electrochemical detection method based on heat‐treated Escherichia coli (E. coli, H‐LSV) was used to investigate the effects of 11 antibiotics with four different antibacterial mechanisms on the electrochemical behavior of E. coli. The results showed that compared to the S‐LSV, the electrochemical signal of E. coli detected by the H‐LSV increased by 362%, and showed a strong linear relationship with bacterial counts up to 1.88×108 CFU/mL, with a detection limit of 1.15×106 CFU/mL. The electrochemical signal consistently correlated with changes in viable E. coli counts following treatment with the four different antibacterial mechanisms. HPLC analysis further confirmed that the changes in purine contents in bacteria after antibiotic treatment were consistent with the trends in electrochemical signals. The evaluation of antibiotic antibacterial ability by H‐LSV showed good consistency with results from plate counting and turbidity methods, but was closer to the results of plate counting. The inhibition rates of antibiotics on E. coli detected by H‐LSV and S‐LSV also showed high consistency, indicating that short‐term high‐temperature treatment of E. coli did not affect the response of the bacterium to the inhibitory activity of antibiotics.

CCR7 depletion alleviates bony growth imbalance following physeal injury in mice

Growth plates are the frequent sites of skeletal injury in children, leading to skeletal growth imbalances. Chemokines, including the receptor CCR7, play a crucial role in stem cell recruitment and cartilage homeostasis, with previous studies linking CCR7 to osteoarthritis progression. However, its role in growth plate cartilage remains unclear. We analyzed the role of CCR7 in the physeal cartilage repair process in mice model. Physeal injury was created in the proximal tibia in 3-week-old C57BL/6 mice (WT) and CCR7-knockout mice (CCR7−/−). Tibial length was measured macroscopically and sections of the physeal injury were analyzed histologically and immunohistochemically. Height and bone volume of the tibial growth plate and bone mineral density (BMD) of the subchondral area were measured by micro-CT. Mesenchymal stem cells (MSCs) were harvested and gene expression after osteogenic differentiation was analyzed using qRT-PCR. At 1, 3 and 5 weeks postoperatively, injured tibiae of CCR7−/− mice were less shortened than those of WT mice. Bone volume of the physeal bridge was significantly lower in CCR7−/− mice than in WT mice. In contrast, BMD of the subchondral area was comparable between CCR−/− and WT mice, and between sham and operated tibiae. In osteogenic differentiation, CCR7−/− mice showed significantly lowered expression of osteogenic markers such as Osterix, Runx2 and Type X collagen. We demonstrated CCR7 depletion in mice inhibited physeal bridge formation and ameliorated growth imbalances after physeal injury.