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BACKGROUND: Assessing the biocompatibility of materials is crucial for ensuring the safety and well-being of patients by preventing undesirable, toxic, immune, or allergic reactions, and ensuring that materials remain functional over time without triggering adverse reactions. To ensure a comprehensive assessment, planning tests that carefully consider the intended application and potential exposure scenarios for selecting relevant assays, cell types, and testing parameters is essential. Moreover, characterizing the composition and properties of biomaterials allows for a more accurate understanding of test outcomes and the identification of factors contributing to cytotoxicity. Precise reporting of methodology and results facilitates research reproducibility and understanding of the findings by the scientific community, regulatory agencies, healthcare providers, and the general public. AIMS: This article aims to provide an overview of the key concepts associated with evaluating the biocompatibility of biomaterials while also offering practical guidance on cellular principles, testing methodologies, and biological assays that can support in the planning, execution, and reporting of biocompatibility testing.

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Identifying the antibacterial mechanisms of elemental silver at the nanoscale remains a significant challenge due to the intertwining behaviors between the particles and their released ions. The open question is which of the above factor dominate the antibacterial behaviors when silver nanoparticles (Ag NPs) with different sizes. Considering the high reactivity of Ag NPs, prior research has primarily concentrated on coated particles, which inevitably hinder the release of Ag+ ions due to additional chemical agents. In this study, we synthesized various Ag NPs, both coated and uncoated, using the laser ablation in liquids (LAL) technique. By analyzing both the changes in particle size and Ag+ ions release, the impacts of various Ag NPs on the cellular activity and morphological changes of gram-negative (E. coil) and gram-positive (S. aureus) bacteria were evaluated. Our findings revealed that for uncoated Ag NPs, smaller particles exhibited greater ions release efficiency and enhanced antibacterial efficacy. Specifically, particles approximately 1.5 nm in size released up to 55 % of their Ag+ ions within 4 h, significantly inhibiting bacterial growth. Additionally, larger particles tended to aggregate on the bacterial cell membrane surface, whereas smaller particles were more likely to be internalized by the bacteria. Notably, treatment with smaller Ag NPs led to more pronounced bacterial morphological changes and elevated levels of intracellular reactive oxygen species (ROS). We proposed that the bactericidal activity of Ag NPs stems from the synergistic effect between particle-cell interaction and the ionic silver, which is dependent on the crucial parameter of particle size.

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Soil waterlogging and drought correspond to contrasting water extremes resulting in plant dehydration. Dehydration in response to waterlogging occurs due to impairments to root water transport, but no previous study has addressed whether limitations to water transport occur beyond this organ or whether dehydration alone can explain shoot impairments. Using common bean (Phaseolus vulgaris) as a model species, we report that waterlogging also impairs water transport in leaves and stems. During the very first hours of waterlogging, leaves transiently dehydrated to water potentials close to the turgor loss point, possibly driving rapid stomatal closure and partially explaining the decline in leaf hydraulic conductance. The initial decline in leaf hydraulic conductance (occurring within 24 h), however, surpassed the levels predicted to occur based solely on dehydration. Constraints to leaf water transport resulted in a hydraulic disconnection between leaves and stems, furthering leaf dehydration during waterlogging and after soil drainage. As leaves dehydrated later during waterlogging, leaf embolism initiated and extensive embolism levels amplified leaf damage. The hydraulic disconnection between leaves and stems prevented stem water potentials from declining below the threshold for critical embolism levels in response to waterlogging. This allowed plants to survive waterlogging and soil drainage. In summary, leaf and stem dehydration are central in defining plant impairments in response to waterlogging, thus creating similarities between waterlogging and drought. Yet, our findings point to the existence of additional players (likely chemicals) partially controlling the early declines in leaf hydraulic conductance and contributing to leaf damage during waterlogging.

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As a leaf vegetable, Gynura bicolor DC (G. bicolor) experiences a rapid deterioration after harvest including insufficient supply of sugar and destruction of cell membranes. In this research, four treatments were experimented on G. bicolor including the control (CK), 12% (g/g) sucrose (ST), 10 µL L-1 1-MCP (MT), and the combination of sucrose and 1-MCP (SMT). The results showed that three treated groups reduced respiratory rate, inhibited hexose consumption and promoted the decrease of starch and sucrose, which was converted into hexose including glucose and fructose to maintain cell membrane integrity. Meanwhile, the activities of AI, NI, SS-C, amylase, and corresponding gene expression levels were significantly up-regulated in three treated groups at 1 d, among which AI played a crucial role in regulating the accumulation of hexose. Furthermore, ST exerted a pronounced effect on hexose accumulation at the beginning while MT reduced hexose consumption through lowered respiratory metabolism during storage. Notably, SMT exhibited an optimum preservation effect on inhibited respiratory metabolism, maintaining cell membrane integrity, enhancing the retention of hexose, indicating that a synergistic effect of ST and MT were developed during storage.

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The widespread bacterial contamination caused by foodborne pathogens has continuously driven the development of advanced and potent food antimicrobial agents. In this study, two novel antimicrobial peptides (AMPs) named KTA and KTR were obtained by modifying a natural AMP, Leg2, from chickpea storage protein legumin hydrolysates. They were further predicted to be stable hydrophobic cationic AMPs of α-helical structure with no hemolytic toxicity by several online servers. Moreover, the AMPs exerted superior antibacterial activity against two representative Staphylococcus aureus strains thanks to the increased hydrophobicity and positive charge, with minimum inhibition concentration value (4.74-7.41 µM) significantly lower than that of Leg2 (>1158.70 µM). Further, this study sought to elucidate the specific antimicrobial mechanism against Gram-positive bacteria. It was found that the electrostatic interactions of the AMPs with peptidoglycan were vital for peptide activity in combating Gram-positive bacteria. Subsequently, the cell membrane of S. aureus cells was irreversibly disrupted by increasing permeability and impairing membrane components, which led to the massive release of intracellular substances and eventual cell death. Overall, this work demonstrated that KTA and KTR were active against Gram-positive bacteria via peptidoglycan targeting and membrane-disruptive mechanisms and paved the way for expanding their application potential to alleviate food contamination.

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Nanoplastics and heavy metals are common pollutants in coastal environments with high concerns, but their joint ecological risk to marine primary productivity remains unclear. In this study, the effects of 7, 70, 700 µg/L lead (Pb) single exposure and in combination with 200 µg/L polystyrene nanoplastics (NPs, 70 nm) on marine microalga Platymonas helgolandica were investigated. Pb single exposure induced a dose-dependent inhibition on the growth of P. helgolandica, which was associated with the reduced photosynthetic efficiency and nutrient accumulation. Compared to Pb single exposure, the addition of NPs significantly reduced the photosynthetic efficiency and aggravated the damage to cell structure. Reduced esterase activity and increased membrane permeability also indicated that NPs exacerbated the adverse effects of Pb on P. helgolandica. Thus, co-exposure to NPs and Pb induced more severe impacts on marine microalgae, suggesting that the joint ecological risk of NPs and heavy metals to marine primary productivity merits more attention.

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Apple production is a dynamic agricultural system in which pesticides are applied recurrently to control pests and diseases in the orchards. Understanding the impact of such agents on non-target organisms is crucial to minimise unintended consequences while maintaining their use in crop protection. The aim was to test how fungicide, herbicide, elicitor, and their combinations affect the physiology of the epiphytic moss Hypnum cupressiforme that naturally occurs in orchards. Our results showed that both dodine and diflufenican applied separately had a strong negative effect on moss physiology reflected in significantly decreased photosynthetic pigment contents, maximum quantum yield of PSII photochemistry, cell membrane integrity and dehydrogenase activity, and increased membrane lipid peroxidation, which indicates a high physiological stress. Furthermore, the combined use of herbicide and fungicide resulted in further deterioration of the physiological condition compared to the effects of both agents used separately. In many cases, the application of chitosan together with a diflufenican or dodine resulted in a reduction of the negative effects triggered by these agents. The compensatory effect was particularly pronounced in maintaining a low level of cell membrane permeability. Consequently, it can be concluded that chitosan could have a protective function against cell membrane damage in non-target mosses.

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Microplastics (MPs), a pervasive pollutant in aquatic environments, are increasingly recognized for their detrimental effects on aquatic organisms. However, the present understanding of their impact on phytoplankton, particularly freshwater microalgae, remains limited. Furthermore, previous studies have predominantly focused on MP particles, largely overlooking the most prevalent form of MPs in aquatic settings-fibers. In this study, we scrutinized the toxicological implications of microplastic fibers (MFs) spanning four distinct lengths (50 µm, 100 µm, 150 µm, and 200 µm) on the protein-nucleated algae Chlorella pyrenoidosa over a six-day period. The study unequivocally demonstrated that MFs markedly impeded C. pyrenoidosa growth, diminished photosynthetic pigment content, and induced oxidative stress, with all observed effects exhibiting a length-dependent correlation. Electron microscopy further revealed notable damage to algal cell membranes. Cell membrane shrinkage, cytoplasm outflow, and abnormalities in cell division were observed in the 150 µm and 200 µm groups. Furthermore, C. pyrenoidosa clustered around the 200 µm MF were notably denser compared to other groups. The present study demonstrated that MFs had length-dependent toxic effects on C. pyrenoidosa. These findings offer novel insights into the deleterious impact of MFs on aquatic organisms, underscoring the pivotal role of length in influencing their toxicity.

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Quantum dots (QDs) with photostable fluorescence are recommended for imaging applications; however, their effect on living cells is incompletely understood. We aimed to elucidate the RAW 264.7 murine macrophage cell line's response to the Si/SiO2 QDs challenge. Cells were exposed to 5 and 15 µg/mL Si/SiO2 QDs for 6 h, 12 h, and 24 h. Cell metabolic activity and viability were assessed by MTT, live/dead, and dye-exclusion assays. Oxidative stress and membrane integrity were assessed by anion superoxide, malondialdehyde, and lactate dehydrogenase activity evaluations. Antioxidative enzyme activities were analyzed by kinetic spectrophotometric methods. Cytokines were analyzed with an antibody-based magnetic bead assay, PGE2 was assessed by ELISA, and Nrf-2, Bcl-2, Beclin 1, and the HSPs were analyzed by western blot. Autophagy levels were highlighted by fluorescence microscopy. The average IC50 dose for 6, 12, and 24 h was 16.1 ± 0.7 µg/mL. Although glutathione S-transferase and catalase were still upregulated after 24 h, superoxide dismutase was inhibited, which together allowed the gradual increase of malondialdehyde, anion superoxide, nitric oxide, and the loss of membrane integrity. G-CSF, IL-6, TNF-α, MIP-1ß, MCP-1, Nrf-2, PGE2, and RANTES levels, as well as autophagy processes, were increased at all time intervals, as opposed to caspase 1 activity, COX-2, HSP60, and HSP70, which were only upregulated at the 6-h exposure interval. These results underscore that Si/SiO2 QDs possess significant immunotoxic effects on the RAW 264.7 macrophage cell line and stress the importance of developing effective strategies to mitigate their adverse impact.

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Excessive use of plant growth stimulants and pesticides is currently a considerable problem, especially in agriculture, horticulture, and arboriculture. Understanding the impacts of these compounds and their combinations on non-target organisms is crucial to minimize unintended consequences, while maintaining their use in plant protection. The aim of this study was to test how long-term spraying with different solutions of natural biostimulator chitosan, synthetic fungicide Switch 62.5 WG, and their combinations affects the physiology of epiphytic lichen Xanthoria parietina naturally occurring in fruit orchards and farmlands. We showed that fungicides composed of fludioxionil and cypronidil, as well as the combined use of such fungicides together with chitosan, can cause the considerable impairment of lichen physiology, and these disturbances relate to both algal and fungal partners of the symbiotic association. This negative effect was especially visible in the loss of cell membrane integrity, the high level of membrane lipid peroxidation, and changes in chlorophyll fluorescence parameters on the last day of the experiment. The combined use of these agents also leads to clear disturbances in the functioning of the mitochondrial respiratory chain, which was manifested by increased NADH dehydrogenase activity, while the use of these compounds separately led to a decrease in the activity of this enzyme. We concluded that the regular use of these agents in fruit tree cultivation may cause serious ecological consequences for epiphytic lichen communities as a result of the death of lichen thalli. This study suggests that the impact of some plant protection agents, both individually and in combinations, merits further attention in terms of their impact on non-target fungi.

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Nanoplastics (NPs) are a matter of widespread concern, as they are easily absorbed by a wide variety of organisms and accumulate in biological tissues. While there is evidence that nanoplastics are toxic to various organisms, few studies have investigated the mechanisms underlying the toxicities of NPs with different surface functionalizations to macrophage cells. In this study, mouse mononuclear macrophage (RAW264.7) cells were exposed to polystyrene nanoplastics (PS-NPs) with three different surface functionalizations, namely pristine polystyrene (PS), carboxyl-functionalized polystyrene (PS-COOH), and amino-functionalized polystyrene (PS-NH2), to evaluate the cellular endocytosis, lactate dehydrogenase (LDH) release, cell viability, reactive oxygen species (ROS), mitochondrial membrane potential, apoptosis, and related gene expression. Results showed that all three PS-NPs were endocytosed into cells. However, in the concentration range of 0-100 µg/mL, PS had no effect on cell viability or apoptosis, but it slightly increased cellular ROS and decreased mitochondrial membrane potential. PS-NH2 exhibited the highest cytotoxicity. PS-COOH and PS-NH2 induced ROS production, altered the mitochondrial membrane potential, and caused cell apoptosis regulated by the mitochondrial apoptosis pathway. Results also showed that cell membrane damage induced by PS-NH2 is one of the primary mechanisms of its cytotoxicity to RAW264.7 cells. The results of this study clarify the toxicities of PS-NPs with different surface functionalizations to macrophages, thereby improving the identification of immune system risks related to nanoplastics.

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Bacterial fruit blotch is one of the most destructing diseases of melon producing-regions. Here, zinc oxide quantum dots (ZnO QDs) were synthesized, and their antibacterial activity against Acidovorax citrulli was investigated. The results indicated that the obtained ZnO QDs displayed 5.7-fold higher antibacterial activity than a commercial Zn-based bactericide (zinc thiazole). Interestingly, the antibacterial activity of ZnO QDs irradiated with light was 1.8 times higher than that of the dark-treated group. It was because ZnO QDs could induce the generation of hydroxyl radicals and then up-regulate the expression of oxidative stress-related genes, finally leading to the loss of cell membrane integrity. A pot experiment demonstrated that foliar application of ZnO QDs significantly reduced the bacterial fruit blotch disease incidence (32.0%). Furthermore, the supply of ZnO QDs could improve the growth of infected melon seedlings by activating the antioxidant defense system. This work provides a promising light-activated quantum-bactericide for the management of pathogenic bacterial infections in melon crop protection.

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Cell membrane integrity is fundamental to the normal activities of cells and is involved in both acute and chronic pathologies. Here, we report a probe for analyzing cell membrane integrity developed from a 9 nm-sized protein nanocage named Dps via fluorophore conjugation with high spatial precision to avoid self-quenching. The probe cannot enter normal live cells but can accumulate in dead or live cells with damaged membranes, which, interestingly, leads to weak cytoplasmic and strong nuclear staining. This differential staining is found attributed to the high affinity of Dps for histones rather than DNA, providing a staining mechanism different from those of known membrane exclusion probes (MEPs). Moreover, the Dps nanoprobe is larger in size and thus applies a more stringent criterion for identifying severe membrane damage than currently available MEPs. This study shows the potential of Dps as a new bioimaging platform for biological and medical analyses. Electronic Supplementary Material: Supplementary material (Figs. S1-S12 including distance information between neighboring fluorophores on Dps, TEM images, MALDI-TOF analysis, fluorescence spectra, confocal images, gel retardation analysis, tissue staining, and additional data) is available in the online version of this article at 10.1007/s12274-022-4785-5.

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The yield and quality of potato can be severely affected by bacterial ring rot, which is caused by Clavibacter michiganensis subsp. sepedonicus (Cms). Recently, using natural compounds to control bacteria has received more attention. In this study, five antibacterial compounds from ethyl acetate (EtOAc) extract of Fructus Polygoni orientalis (FPO) against Cms were isolated and the most active compound was screened. Five active compounds were identified as 3,3'-di-O-methylellagic acid (1), 3,3'-di-O-methylellagic acid-4-O-ß-D-glucopyranoside (2), dihydroquercetin (3), protocatechuic acid (4) and quercetin (5). Compound 3 (dihydroquercetin, DHQ) was confirmed as the most active compound. The diameter of inhibition zone (DIZ), minimum inhibitory concentration (MIC), protective efficiency and curative efficiency of DHQ were 22.50 mm, 0.313 mg/mL, 84.49% and 79.63%, respectively, which exceeded these of thiophanate-methyl (TM) in antibacterial activity assays; this indicated that DHQ had satisfactory antibacterial activities against Cms in vitro and in vivo. Results of cell membrane damage assessments indicated that DHQ could reduce membrane potential (MP), disrupt the cell membrane integrity, and promote the leakage of nucleic acids and proteins. Overall, these findings suggested that DHQ could serve as a promising lead molecular against Cms, which could provide a basis for its further derivatization.

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With the increase in alcohol consumption, more and more people are suffering from alcoholic liver disease (ALD). Therefore, it is necessary to elaborate the pathogenesis of ALD from the aspects of alcohol metabolism and harm. In this study, we established an alcoholic liver injury model in vitro by inducing L02 cells with different concentration of ethanol and acetaldehyde. Results showed that the metabolism of ethanol can promote the content of ROS, MDA, TNF-α, IL-6, and caspase 3, causing oxidative and inflammatory stress and membrane permeability changes. However, unmetabolized ethanol and acetaldehyde had little effect on cell membrane permeability and inflammation, indicating that ethanol metabolites were the main reason for cell membrane damage. We also evaluated the effects of amino acids (taurine and methionine), vitamins (E and vitamin D), organic acids (malic acid and citric acid), flavonoids (rutin and quercetin), and phenolic acids (ferulic acid and chlorogenic acid) on alcohol-induced cell membrane damage of L02 cells. Chlorogenic acid, taurine, vitamin E, and citric acid had remarkable effects on improving cell membrane damage. Malic acid, rutin, quercetin, and ferulic acid had obvious therapeutic effects, while vitamin D and methionine had poor therapeutic effects. The relationship between the structure and effect of active ingredients can be further studied to reveal the mechanism of action, and monomers can be combined to explore whether there is a synergistic effect between functional components, in order to provide a certain theoretical basis for the actual study of liver protection.

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Maize (Zea mays L.) is the second most commonly produced and consumed crop after wheat globally and is adversely affected by high heat, which is a significant abiotic stress factor. This study was carried out to determine the physiological and biochemical responses of hybrid corn varieties under heat stress ('HS') compared to control ('C') conditions during the 2020 and 2021 growing seasons. The experiment was conducted under natural conditions in the Southeastern region of Turkey, where the most intense temperatures are experienced. This experiment used split plots in randomized blocks with three replications, with 'HS' and 'C' growing conditions applied to the main plots and the different hybrid corn varieties (FAO 650) planted on the sub plots. Mean values of days to 50% tasseling (DT, day), grain yield (GY, kg ha-1), leaf water potential (LWP, %), chlorophyll-a (Chl-a, mg g-1), cell membrane damage (CMD, %), and total phenol content (TPC, µg g-1) were significantly different between years, growing conditions, and hybrid corn varieties. Changes in the climate played a significant role in the differences between the years and growing conditions (GC), while the genetic characteristics of the different corn varieties explained the differences in outcomes between them. The values of DT, GY, LWP, Chl-a, CMD, and TPC ranged from 49.06-53.15 days, 9,173.0-10,807.2 kg ha-1, 78.62-83.57%, 6.47-8.62 mg g-1, 9.61-13.54%, and 232.36-247.01 µg g-1, respectively. Significant correlations were recorded between all the parameters. Positive correlations were observed between all the variables except for CMD. The increased damage to cell membranes under 'HS' caused a decrease in the other measured variables, especially GY. In contrast, the GY increased with decreased CMD. CMD was important in determining the stress and tolerance level of corn varieties under 'HS' conditions. The GY and other physiological parameters of ADA 17.4 and SYM-307 candidate corn varieties surpassed the control hybrid corn cultivars. The results revealed that the ADA 17.4 and SYM-307 cultivars might have 'HS'-tolerate genes.

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Environment-friendly algaecides based on allelopathy have been widely used to control harmful algal blooms. In this research, micro and nano scale artemisinin sustained-release algal inhibitor was prepared, the optimal preparation conditions were explored, and the inhibitory mechanism of artemisinin algaecides was turned perfect. The results showed that when the particle size of artemisinin sustained-release microspheres (ASMs) was 2/10,000 of artemisinin sustained-release granules (ASGs), the inhibitory effect was more remarkable. The optimal concentration of ASMs was 0.2 g L-1, and the inhibitory effect reached 99% on the 10th day. The algal density and chlorophyll a both showed a downward trend, indicating that ASGs and ASMs could promote the degradation of chlorophyll a. The inhibition rate of ASGs was faster than that of ASMs on the 4th day, and the inhibitory effect of ASMs was more significant after the 5th day. The activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) increased rapidly at first and then decreased, which indicated that ASGs and ASMs caused oxidative damage to Microcystis aeruginosa and inhibited the activity of antioxidant enzymes. Furthermore, the content of the oxygen free radical (O2-) and malondialdehyde (MDA) continued to rise after the 5th day, and the protein, nucleic acid, and conductivity in the culture medium increased. These results showed that lipid peroxidation occurred in the algal cell membrane, and the permeability of the membrane increased. In summary, the ASMs had a significant sustained inhibitory effect while the ASGs had a better short-term effect. The main inhibitory mechanism of artemisinin algaecides is the irreversible damage of cell membrane.

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Surfactin, an antibacterial lipopeptide produced by different strains of Bacillus subtilis, is a powerful biosurfactant. It also has multiple biological activities including antiviral, anti-mycoplasma and antiprotozoal activities, in addition to the broad-spectrum antimicrobial activities against Gram-positive bacteria, Gram-negative bacteria and fungi. Surfactin may be one of the promising alternatives to antibiotics. Surfactin's chemical structure and physicochemical properties are briefly discussed in this mini-review. Surfactin's antibacterial mechanism is mainly outlined as follows: (1) attacking pathogenic bacteria's cell membrane, causing cell membrane disintegration or osmotic pressure imbalance; (2) inhibiting pathogenic bacteria's protein synthesis, preventing cell reproduction; (3) inhibiting pathogenic bacteria's enzyme activity, affecting normal cell metabolism. This provides basis for the further research and application of surfactin. Finally, the application of surfactin in food and its prospect are summarized in brief.

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Salmonella enterica serovars Enteritidis (S. Enteritidis) can survive extreme food processing environments including bactericidal sodium hypochlorite (NaClO) treatments generally recognized as safe. In order to reveal the molecular regulatory mechanisms underlying the phenotypes, the overall regulation of genes at the transcription level in S. Enteritidis after NaClO stimulation were investigated by RNA-sequencing. We identified 1399 differentially expressed genes (DEG) of S. Enteritidis strain CVCC 1806 following treatment in liquid culture with 100 mg/L NaClO for 20 min (915 upregulated and 484 downregulated). NaClO stress affects the transcription of genes related to a range of important biomolecular processes such as membrane damage, membrane transport function, energy metabolism, oxidative stress, DNA repair, and other important processes in Salmonella enterica. First, NaClO affects the structural stability of cell membranes, which induces the expression of a range of outer and inner membrane proteins. This may lead to changes in cell membrane permeability, accelerating the frequency of DNA conversion and contributing to the production of drug-resistant bacteria. In addition, the expression of exocytosis pump genes (emrB, yceE, ydhE, and ydhC) was able to expel NaClO from the cell, thereby increasing bacterial tolerance to NaClO. Secondly, downregulation of genes related to the Kdp-ATPase transporter system (kdpABC) and the amino acid transporter system (aroP, brnQ and livF) may to some extent reduce active transport by bacterial cells, thereby reducing their own metabolism and the entry of disinfectants. Downregulation of genes related to the tricarboxylic acid (TCA) cycle may drive bacterial cells into a viable but non-culturable (VBNC) state, resisting NaClO attack by reducing energy metabolism. In addition, significant upregulation of genes related to oxidative stress could mitigate damage caused by disinfectants by eliminating alkyl hydroperoxides, while upregulation of genes related to DNA repair could repair damage to bacterial cells caused by oxidative stress. Therefore, this study indicated that S. Enteritidis has genomic mechanisms to adapt to NaClO stress.

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BCp12 is a novel casein-derived antibacterial peptide with a broad-spectrum antibacterial effect. However, its action mechanism against E. coli is unknown. In this study, the growth curve showed that BCp12 had excellent antibacterial activity against E. coli. Red (propidium iodide staining) and green (fluorescein isothiocyanate staining) fluorescence signals were detected at the edges of the E. coli cells treated with BCp12. scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that E. coli cells became rough and shrunken, and part of the cell contents leaked to form a cavity. Furthermore, the iTRAQ proteome analysis showed that 193 and 174 proteins were significantly up-regulated and down-regulated, respectively, after BCp12 treatment. Four enzymes involved in fatty acid degradation of E. coli were down-regulated, disrupting the synthesis of cell membranes. Molecular docking and gel retardation assays showed that BCp12 could bind to genes encoding four key enzymes involved in the fatty acid degradation pathway through hydrogen bonding and hydrophobic interactions, thus significantly inhibiting their activities. Overall, the results indicate that BCp12 inhibits the growth of E. coli, causing metabolic disorders, thus destroying the structure of cell membranes.