Catalase Treatment Research Articles

Myoglobin inhibits breast cancer cell fatty acid oxidation and migration via heme-dependent oxidant production and not fatty acid binding

The monomeric heme protein myoglobin (Mb) is aberrantly expressed in approximately 40 % of breast tumors. Mb expression is associated with better patient prognosis, yet the molecular mechanisms underlying this effect are unclear. In muscle, Mb's heme moiety confers oxygen storage and delivery. However, prior studies demonstrate that low levels of Mb in cancer cells preclude this function. Several studies propose a fatty acid binding function for Mb via lysine residue K46. Because cancer cells can upregulate fatty acid oxidation (FAO) to fuel cell migration, we tested whether Mb-mediated fatty acid binding modulates FAO and migration. We demonstrate that stable expression of human Mb in MDA-MB-231 breast cancer cells decreases cell migration and FAO. Site-directed mutagenesis of Mb K46 disrupted fatty acid binding but did not improve FAO or migration. Conversely, cells expressing Apo-Mb (with disrupted heme binding) did not show impaired FAO or migration rates, suggesting Mb attenuates FAO and migration via a heme-dependent mechanism rather than through fatty acid binding. Mb's heme-dependent oxidant generation dysregulates migratory gene expression, which is reversed by catalase treatment. Collectively, these data demonstrate that Mb's heme-dependent oxidant production decreases breast cancer cell migration, prompting therapeutic strategies to modulate oxidant production and Mb in tumors.

Mitochondrial antioxidants abate SARS-COV-2 pathology in mice

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection inhibits mitochondrial oxidative phosphorylation (OXPHOS) and elevates mitochondrial reactive oxygen species (ROS, mROS) which activates hypoxia-inducible factor-1alpha (HIF-1α), shifting metabolism toward glycolysis to drive viral biogenesis but also causing the release of mitochondrial DNA (mtDNA) and activation of innate immunity. To determine whether mitochondrially targeted antioxidants could mitigate these viral effects, we challenged mice expressing human angiotensin-converting enzyme 2 (ACE2) with SARS-CoV-2 and intervened using transgenic and pharmacological mitochondrially targeted catalytic antioxidants. Transgenic expression of mitochondrially targeted catalase (mCAT) or systemic treatment with EUK8 decreased weight loss, clinical severity, and circulating levels of mtDNA; as well as reduced lung levels of HIF-1α, viral proteins, and inflammatory cytokines. RNA-sequencing of infected lungs revealed that mCAT and Eukarion 8 (EUK8) up-regulated OXPHOS gene expression and down-regulated HIF-1α and its target genes as well as innate immune gene expression. These data demonstrate that SARS-CoV-2 pathology can be mitigated by catalytically reducing mROS, potentially providing a unique host-directed pharmacological therapy for COVID-19 which is not subject to viral mutational resistance.

The Antibacterial Properties of Polish Honey against Streptococcus mutans-A Causative Agent of Dental Caries.

Streptococcus mutans is considered the main pathogen responsible for dental caries, one of the major infectious diseases, affecting more than 4 billion people worldwide. Honey is a natural product with well-known antibacterial potential against several human pathogens. The aim of the study was to evaluate the antibacterial efficacy of Polish honey against S. mutans and analyze the role of some bioactive substances on its antibacterial action. The antibacterial potential of different honey varieties (goldenrod, buckwheat, honeydew, and lime) was analyzed using a microdilution assay. Manuka and artificial honey were used as controls. The content of GOX, hydrogen peroxide, total polyphenols, and antioxidant potential was assayed in honey. The influence of catalase and proteinase K on antibacterial activity as well as antibiofilm action was also determined. The strongest antibacterial activity was observed for buckwheat, honeydew, and manuka honey, which were also characterized by the highest antioxidant activity and polyphenols content. Catalase treatment decreases the antibacterial activity of honey, while proteinase K treatment influences the antibacterial potential of honey slightly less. Obtained results suggest that honey can be a good natural product against S. mutans, and hydrogen peroxide was identified as a crucial contributor to its antimicrobial action.

The Role Of Bee-Propolis As Antioxidants On Antioxidant Enzymes Inmale Rabbits

Propolis has been reported to be important antioxidantThe biological effects exhibited by propolis could be related to an overall effect of the phenolic compounds present in propolis (flavonol galangin; hydroxycinnamic acids, caffeic acid, p-cumaric acid, ferulic acid and caffeic acid phenethyl ester Rabbits were orally given propolis (50 mg/kg bw) was given alone. The tested doses were given to rabbits every day for 12 weeks. The effects of propolis on plasma and testes homogenates thiobarbituric acid-reactive substances (TBARS), antioxidant enzyme glutathione (GSH), glutathione peroxidase (GPx), glutathione S- transferase (GST), catalase (CAT) and superoxide dismutase (SOD) activities Treatment with propolis caused significant (P<0.05) increase in the activity of antioxidant enzyme GSH, GPx, GST, SOD and CAT in plasma and testes homogenates compared to control. While, propolis caused a significant (P<0.05) decrease in blood plasma and testes homogenates TBARS as compared with control.

Streptococcus pneumoniae disrupts the structure of the golgi apparatus and subsequent epithelial cytokine response in an H2O2-dependent manner

BackgroundLung infections caused by Streptococcus pneumonia are a global leading cause of death. The reactive oxygen species H2O2 is one of the virulence factors of Streptococcus pneumoniae. The Golgi apparatus is essential for the inflammatory response of a eukaryotic cell. Golgi fragmentation was previously shown to be induced by bacterial pathogens and in response to H2O2 treatment. This led us to investigate whether the Golgi apparatus is actively involved and targeted in host–pathogen interactions during pneumococcal infections.MethodsFollowing in vitro infection of BEAS-2B bronchial epithelial cells with Streptococcus pneumoniae for 16 h, the structure of the Golgi apparatus was assessed by fluorescence staining of the Golgi-associated protein, Golgin-97. To investigate the effect of H2O2 production on Golgi structure, BEAS-2B cells were treated with H2O2 or the H2O2 degrading enzyme Catalase, prior to Golgi staining. Artificial disruption of the Golgi apparatus was induced by treatment of cells with the GBF1 inhibitor, Golgicide A. A proinflammatory cellular response was induced by treatment of cells with the bacterial cell wall component and TLR4 ligand lipoteichoic acid.ResultsIn vitro infection of bronchial epithelial cells with wild type Streptococcus pneumoniae led to a disruption of normal Golgi structure. Golgi fragmentation was not observed after deletion of the pneumococcal H2O2-producing gene, spxB, or neutralization of H2O2 by catalase treatment, but could be induced by H2O2 treatment. Streptococcus pneumoniae infection significantly reduced host cell protein glycosylation and artificial disruption of Golgi structure significantly reduced bacterial adherence, but increased bacterial counts in the supernatant. To understand if this effect depended on cell-contact or soluble factors, pneumococci were treated with cell-supernatant of cells treated with Golgicide A and/or lipoteichoic acid. This approach revealed that lipoteichoic acid conditioned medium inhibits bacterial replication in presence of host cells. In contrast, artificial Golgi fragmentation by Golgicide A treatment prior to lipoteichoic acid treatment rescued bacterial replication. This effect was associated with an increase of IL-6 and IL-8 in the supernatant of lipoteichoic acid treated cells. The increased cytokine release was abolished if cells were treated with Golgicide A prior to lipoteichoic acid treatment.ConclusionStreptococcus pneumoniae disrupts the Golgi apparatus in an H2O2-dependent manner, thereby inhibiting paracrine anti-infective mechanisms.EnamKsCfhZcCbpPUq5E2ztVideo

ANTIOXIDANT ACTIVITIES OF MORINGA OLEIFERA LEAF EXTRACT AGAINST ARSENIC INDUCED TOXICITY IN CIRRHINUS MRIGALA

This experimental study was conducted to evaluate the antioxidant activities of Moringa oleifera leaf extract against Arsenic (As) induced toxicity in Cirrhinus mrigala in Tawakkal Fish Hatchery at Muzaffargarh, Punjab, Pakistan. 288 fingerlings were collected from fish pond and kept in circular tank for acclimatization. 12 fish about 100-day old having similar size were selected randomly and kept in separate glass aquaria for each treatment groups T1, T2, T3 and control group T4. Fish in treatments groups T1, T2 and T3 were exposed with water born sublethal concentration of 1/10th LC50 of arsenic (As) for 7days (240 hours). On 8th and 16th days of the experiment three fish were collected from each aquarium, humanly dissected targeted organ was taken out and used for liver, muscle, and gills antioxidant enzyme activities and histopathological alteration. The findings indicate that in treatment group T2 which feed with 2% and 4% Moringa oleifera supplemented diet reduced significantly (P<0.05) arsenic induced oxidative stress in fish, enhance the superoxide dismutase and catalase activities but treatment group T2 is 2% Moringa oleifera supplemented diet is more effective near to control group T4 as compared to treatment group T3 with 4% Moringa oleifera supplemented. After 16 days exposure of 1/10th concentration of arsenic with 0% Moringa oleifera various degenerative alteration were seen in gills. In 2% and 4% Moringa oleifera with 1/10th arsenic, spiked secondary lamellae and lamellar epithelium lifting (EL) and rupture of epithelial layer (↑↑) and fusion of lamellae were observed at several points. Moringa oleifera is medicinal herb, which has various tremendous benefits.

Exogenous catalase treatment enhances CD8+ T cell functionality and hinders T cell exhaustion

Abstract ROS are small short-lived oxygen-containing molecules which are highly chemically reactive and involved in the regulation of biological processes like T cell activation and proliferation. The tumor microenvironment (TME) is a metabolically hostile environment with a deficiency in nutrients like glucose and glutamine, accumulation of tumor-driven metabolic waste, and extreme hypoxia. Hypoxia results in impaired mitochondrial function and generation of excess levels of ROS, which have been known to promote T cell exhaustion. Here, we investigated how exogenous treatment of antioxidant catalase altered CD8+ T cell effector responses and T cell exhaustion using OT-I TCR transgenic mice. During CD8+ T cell effector differentiation in vitro by stimulation with cognate antigen followed by culture with IL-2, addition of catalase significantly enhanced T cell activation and effector differentiation. Catalase-treated effector cells had higher expression of critical activation markers including CD69 and CD25, increased expression of the stemness marker TCF-1, and enhanced secretion of effector cytokines IFNγ and TNFα. During induction of T cell exhaustion in vitro by co-culture with B16 melanoma expressing ovalbumin (B16-Ova), catalase-treated OT-I T cells had significantly increased cytotoxic activity, enhanced expression of CD25 and lower co-expression of PD-1 and TIM-3 relative to non-treated OT-I T cells. Our findings uncover a new role for catalase in altering the fate of CD8+ effector T cells and potentially a new therapeutic tool for managing T cell exhaustion. NIH (R01 CA212605)

Hibiscus sabdariffa fractions attenuate oxidative stress and some cardiac biomarkers in sodium fluoride(NaF)-induced cardiotoxicity rat

The excessive intake and bioaccumulation of sodium fluoride (NaF) through water, toothpaste or pesticides could trigger cardiac oxidative stress. The effects of Hibiscus sabdariffa (HS) fractions on biochemical markers of the heart in NaF-induced rats. Thirty male and female rats were grouped into five: Normal control (NC) received water only, Sodium fluoride (NaF, 300 mg L−1), the others were exposed to 300 mg L−1 NaF while the treated animals received100 mg kg−1d−1 of aqueous, n-hexane and butanol -H. sabdariffa (AQE-HS, HEE-HS, BTE-HS) fractions orally for 14 days respectively. This study revealed that NaF exposure increases TBARS, TC, TG, LDL-c, AI, AC, CRI-I, CRI-II and arginase activity with a decrease in catalase, GST, SOD, GSH, HDL-c, and NO level whilethe HS treatment stimulates antioxidant production which eventually reduce oxidative stress. The AQE-HS suppressed TBARS, lipid profile, and cardiac indices. Therefore, bioactive constituent of HS attenuates NAF-induced cardiac oxidative stress.

Amine oxidase copper-containing 3 aggravates cardiac remodelling by generating hydrogen peroxide after myocardial infarction.

Amine oxidase copper-containing 3 (AOC3) is a member of the semicarbazide-sensitive amine oxidase enzyme family. It acts as an ectoenzyme catalysing the oxidative deamination of primary amines and generating hydrogen peroxide (H2 O2 ). While AOC3 is implicated in cardiovascular diseases such as atherosclerosis, its role in cardiac remodelling after myocardial infarction (MI) is unclear. In this study, we first confirmed a long-term upregulation of AOC3 in both cardiac myofibroblasts after MI in vivo and angiotensin II (ANGII)-treated cardiac fibroblasts in vitro. AOC3 knockdown not only inhibited the activation of cardiac fibroblasts induced by ANGII but also alleviated cardiac fibrosis in mice after MI. Using sh-AOC3 lentiviruses, exogenous recombinant AOC3 (r-AOC3), semicarbazide (an AOC3 inhibitor), and catalase (a hydrogen peroxide scavenger) treatments, we also demonstrated that AOC3 promoted H2 O2 generation, increased oxidative stress, and enhanced ERK1/2 activation, which were responsible for the activation of cardiac fibroblasts. In particular, AOC3 knockdown also improved cardiac function and hypertrophy after MI. Through a coculture system, we confirmed that AOC3 expressed on cardiac myofibroblasts was able to enhance oxidative stress and induce hypertrophy of cardiomyocytes by promoting H2 O2 generation. Similarly, r-AOC3 promoted H2 O2 generation and resulted in oxidative stress and hypertrophy of cardiomyocytes, which were almost inhibited by both semicarbazide and catalase. In conclusion, AOC3 plays a critical role in cardiac fibrosis and hypertrophy after MI by promoting the generation of H2 O2 . AOC3 is a promising therapeutic target against cardiac remodelling. © 2023 The Pathological Society of Great Britain and Ireland.

The Role of Catalase and Pyruvate on the Recovery of Cold - Shocked Bacteria

The study principally aimed at evaluating different additives to the culture medium for the recovery of cold-shocked bacteria isolated from chilled carcasses. Sixty randomly selected beef carcasses were assigned for investigation from which 630 swabs were collected for assessment of microbiological contamination of carcasses during the processes after skinning and evisceration, along the washing to the chilling stage. Obtained results were analysed by statistical package (SAS 2000, version 9.0) and revealed bacterial counts decreased significantly (p≤0.05) from skinning to chilling (3.67±0.0 to 1.23±0.10, p≤0.01). The predominant bacteria isolated from the carcasses were Staphylococcus spp. followed by Enterobacteriaceae and Pseudomonas spp. To test for recovery of cold-shocked bacteria, the bacterial load as CFU was evaluated after treatments with catalase, pyruvate and their combination. The CFU of samples from chilled carcasses increased after treatment with catalase and pyruvate (1.23±0.52 vs. 2.54±0.12 and 2.42±0.33, respectively; p≤0.05). The results showed that catalase treatment has induced higher bacterial recovery compared to pyruvate alone or the combination of pyruvate and catalase, but the bacteria died when the concentration of catalase and pyruvate was increased. Addition of catalase or pyruvate to plate count agar medium gives true estimates of the bacterial load of chilled carcasses and other cold foods.

Gene expression analysis during the conversion from a viable but nonculturable to culturable state in Vibrio cholerae

We previously reported that Vibrio cholerae in a viable but non-culturable (VBNC) state can be converted to a culturable state by treatment with catalase. This finding enabled us to develop an assay system to observe the time course of the conversion from VBNC to culturable in V. cholerae. VBNC cells began to convert to culturable cells as early as 2 h after catalase supplementation. Gene expression in VBNC cells during catalase treatment was analyzed using RNA microarray. Many ribosomal DNA genes were stimulated 6 h post catalase exposure, suggesting that the conversion-driving signal started prior to 6 h. Focusing on the period prior to cell proliferation, we found that 16 genes might be involved in the conversion mechanism in V. cholerae, and they showed enhanced expression at 2 h and 4 h after catalase addition. These upregulated genes included phage shock proteins (pspA, B, and C), alternative sigma factor (rpoE) and its negative regulator (rseA), cobW C terminal domain-containing protein, damage-inducible helicase (dinG), cholerae toxin secretion protein epsM, HTH-type transcription regulator (iscR), mechanosensitive ion channel family protein, anthranilate synthase component I, fructose-specific IIBC component, molybdenum import ATP-binding protein (modC), LysE family translocator, putative organic hydroperoxide resistance protein, and a hypothetical protein. This study identified genes involved in the catalase-induced conversion of V. cholerae VBNC cells to a culturable state and provided valuable insights into the mechanisms involved in the conversion process.

Bactericidal and non-cytotoxic activity of bacteriocin produced by Lacticaseibacillus paracasei F9-02 and evaluation of its tolerance to various physico-chemical conditions.

This study aims to explore novel lactic acid bacteria (LAB) from breast-fed infants' faeces towards characterizing their antimicrobial compound, bacteriocin. The LAB, Lacticaseibacillus paracasei F9-02 showed strong antimicrobial activity against clinical pathogens. Their proteinaceous nature was confirmed as the activity was completely abolished when treated with proteinaceous enzymes and retained during neutral pH and catalase treatment. The purified bacteriocin showed antimicrobial activity at the minimum inhibitory concentration (MIC) value of 7.56 μg/ml against vancomycin-resistant Enterococcus sp. [vancomycin-resistant enterococcal (VRE)], and methicillin-resistant Staphylococcus aureus (MRSA), 15.13 μg/ml against Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella enterica subsp. enterica serotype typhi and 30.25 μg/ml against Shigella flexneri. Present study also proved the bactericidal, non-cytotoxic and non-hemolytic nature of bacteriocin. Additionally, bacteriocin retained their stability under various physico-chemical conditions, broad range of pH (2-10), temperature (40-121°C), enzymes (amylase, lipase and lysozyme), surfactants [Tween-20, 80, 100 and sodium dodecyl sulfate (SDS)], metal ions (CaCl2 , FeSO4 , ZnSO4 , MgSO4 , MnSO4 , CuCl2 ) and NaCl (2%-8%). The molecular weight of bacteriocin (~28 kDa) was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), functional and active groups were assessed by Fourier Transform-Infrared (FT-IR). To our knowledge, this is the first study reporting L. paracasei from breast-fed infants' faeces and assessing their antimicrobial compound, bacteriocin. The study results furnish the essential features to confirm the therapeutic potential of L. paracasei F9-02 bacteriocin.

Vitamin C Maintenance against Cell Growth Arrest and Reactive Oxygen Species Accumulation in the Presence of Redox Molecular Chaperone hslO Gene.

Chromosome damage combined with defective recombinase activity renders cells inviable, owing to deficient double-strand break repair. Despite this, recA polA cells grow well under either DNA damage response (SOS) conditions or catalase medium supplementation. Catalase treatments reduce intracellular reactive oxygen species (ROS) levels, suggesting that recA polA cells are susceptible to not only chronic chromosome damage but also ROS. In this study, we used a reducing agent, vitamin C, to confirm whether cell growth could be improved. Vitamin C reduced ROS levels and rescued colony formation in recAts polA cells under restrictive temperatures in the presence of hslO, the gene encoding a redox molecular chaperone. Subsequently, we investigated the role of hslO in the cell growth failure of recAts polA cells. The effects of vitamin C were observed in hslO+ cells; simultaneously, cells converged along several ploidies likely through a completion of replication, with the addition of vitamin C at restrictive temperatures. These results suggest that HslO could manage oxidative stress to an acceptable level, allowing for cell division as well as rescuing cell growth. Overall, ROS may regulate several processes, from damage response to cell division. Our results provide a basis for understanding the unsolved regulatory interplay of cellular processes.

Ubiquitination as a key regulatory mechanism for O3-induced cutaneous redox inflammasome activation

NLRP1 is one of the major inflammasomes modulating the cutaneous inflammatory responses and therefore linked to a variety of cutaneous conditions. Although NLRP1 has been the first inflammasome to be discovered, only in the past years a significant progress was achieved in understanding the molecular mechanism and the stimuli behind its activation. In the past decades a crescent number of studies have highlighted the role of air pollutants as Particulate Matter (PM), Cigarette Smoke (CS) and Ozone (O3) as trigger stimuli for inflammasomes activation, especially via Reactive Oxygen Species (ROS) mediators. However, whether NLRP1 can be modulated by air pollutants via oxidative stress and the mechanism behind its activation is still poorly understood. Here we report for the first time that O3, one of the most toxic pollutants, activates the NLRP1 inflammasome in human keratinocytes via oxidative stress mediators as hydrogen peroxide (H2O2) and 4-hydroxy-nonenal (4HNE). Our data suggest that NLRP1 represents a target protein for 4HNE adduction that possibly leads to its proteasomal degradation and activation via the possible involvement of E3 ubiquitin ligase UBR2. Of note, Catalase (Cat) treatment prevented inflammasome assemble and inflammatory cytokines release as well as NLRP1 ubiquitination in human keratinocytes upon O3 exposure.The present work is a mechanistic study that follows our previous work where we have showed the ability of O3 to induce cutaneous inflammasome activation in humans exposed to this pollutant. In conclusion, our results suggest that O3 triggers the cutaneous NLRP1 inflammasome activation by ubiquitination and redox mechanism.

Lactose Concentration in Low-Lactose and Lactose-Free Milk, Milk Products, and Products Containing Dairy Ingredients by High Sensitivity Enzymatic Method (K-LOLAC), Collaborative Study: Final Action 2020.08.

The AOAC Stakeholder Panel on Strategic Food Analytical Methods issued a call for methods in 2018 for the measurement of lactose in low-lactose and lactose-free products under Standard Method Performance Requirement (SMPR®) 2018.009. Megazyme's Lactose Assay Kit (K-LOLAC) was reviewed and accepted as a First Action Official MethodSM in 2020 (2020.08). A collaborative study was conducted to evaluate the to evaluate the reproducibility of AOAC Official MethodSM2020.08 for the measurement of lactose concentration in low-lactose and lactose-free milk, milk products, and products containing dairy ingredients. Samples are deproteinated and clarified by treatment with Carrez reagents, and then free glucose is removed using a glucose oxidase and catalase treatment system. Quantification of lactose is based on the hydrolytic activity of β-galactosidase, which hydrolyses lactose to glucose and galactose. Any remaining free D-glucose is first measured using a hexokinase (HK)/glucose 6-phosphate dehydrogenase (G-6PDH)/6-phosphogluconate dehydrogenase (6-PGDH) based assay procedure, and then β-galactosidase is added to hydrolyze the lactose in the same reaction vessel with concurrent measurement of the released D-glucose. The samples analyzed included a number of lactose-free and low-lactose milk samples, lactose-free infant formula, lactose-free milkshake, lactose-free adult nutritional drink, lactose-free cream, and lactose-free cheese. All materials had repeatability relative standard deviations (RSDr) <7%. The reproducibility relative standard deviation (RSDR) varied from 3.8 to 14.9% with seven of the 10 test samples having an RSDR of <10%. The Lactose Assay Kit (K-LOLAC) meets the requirements for reproducibility set out under SMPR 2018.009. The Lactose Assay (K-LOLAC) is a robust, simple, and reproducible method for analysis of lactose in foodstuffs and beverages.

Lack of evidence for the oxidative stress theory of bleaching in the sea anemone, Exaiptasia diaphana, under elevated temperature

To survive in nutrient-poor waters corals rely on a symbiotic association with intracellular microalgae. However, increased sea temperatures cause algal loss—known as coral bleaching—often followed by coral death. Some of the most compelling evidence in support of the ‘oxidative stress theory of coral bleaching’ comes from studies that exposed corals, cultures of their algal endosymbionts, or the coral model Exaiptasia diaphana to exogenous antioxidants during thermal stress. Here, we replicate these experiments using E.diaphana with the addition of the antioxidants ascorbate + catalase, catechin, or mannitol under ambient and elevated temperatures along with an antioxidant-free control. In the absence of exogenous antioxidants, E.diaphana exposed to elevated temperatures bleached with no change in reactive oxygen species (ROS) levels associated with their microalgal cells. Ascorbate + catalase and mannitol treatments rescued the anemones from bleaching, although microalgal ROS levels increased in these antioxidant treatments under elevated temperature conditions. While bleaching was not associated with changes in net ROS for the intracellular algal symbionts, it is evident from our findings that excess ROS is connected to the bleaching phenotype as exogenous antioxidants were successful in mitigating the effects of thermal stress in cnidarians. This understanding may assist applied research that aims to reduce the impact of climate change on coral reefs.

Antifungal Activity of Lactobacillus plantarum ZZUA493 and Its Application to Extend the Shelf Life of Chinese Steamed Buns.

Lactic acid bacteria (LAB) can produce many kinds of antifungal substances, which have been widely proven to have antifungal activity. In this study, 359 strains of LAB were screened for antifungal activity against Aspergillus niger (A. niger) using the 96-well microtiter plate method, and three showed strong activity. Of these, ZZUA493 showed a broad-spectrum antifungal ability against A. niger, Aspergillus oryzae, Trichoderma longibrachiatum, Aspergillus flavus and Fusarium graminearum. ZZUA493 was identified as Lactobacillus plantarum. Protease treatment, the removal of hydrogen peroxide with catalase and heat treatment had no effect on the antifungal activity of the cell-free supernatant (CFS) of ZZUA493; organic acids produced by ZZUA493 appeared to have an important role in fungal growth inhibition. The contents of lactic acid, acetic acid and phenyllactic acid in the CFS tended to be stable at 48 h, and amounted to 28.5, 15.5 and 0.075 mg/mL, respectively. In addition, adding ZZUA493, as an ingredient during their preparation, prolonged the shelf life of Chinese steamed buns. Overall, ZZUA493 appears to have good potential as a fungal inhibitor for food preservation.

Isolation and partial characterization of a novel bacteriocin from Pseudomonas azotoformans with antimicrobial activity against Pasterella multocida.

In this study, a bacteriocin PA996 isolated from Pseudomonas azotoformans (P. azotoformans) was purified to homogeneity by ammonium sulphate precipitation and SP-Sepharose column chromatography. P. azotoformans began to grow at 6h, reached exponential phase at 12-18h. Bacteriocin PA996 was produced at 18h and reached a maximum level of 2400AU/mL. The molecular mass of purified bacteriocin PA996 was estimated by SDS-PAGE and its molecular mass was approximately 50kDa. By screening in vitro, the bacteriocin PA996 showed an antimicrobial activity against Pasteurella multocida (P. multocida). The bacteriocin PA996 showed antibacterial activity in the range of pH2-10 and it was heat labile. The inhibitory activities were diminished after treatment with proteinase K, trypsin and papain, respectively, while catalase treatment was ineffective. The minimal inhibitory concentration (MIC) and bactericidal kinetics curves showed that the bacteriocin PA996 had a good inhibitory ability against P. multocida. Our data indicate that bacteriocin PA996 could inhibit the growth of P. maltocida and it may have the potential to apply as an alternative therapeutic drug.

Effects of enzymatic and non-enzymatic antioxidants in diluents on cryopreserved bull epididymal sperm

Objective: To evaluate the supplementation effects of vitamin E, vitamin C, superoxide dismutase (SOD), and catalase to diluents on bull cryopreserved epididymal sperm. Methods: Sperm were retrieved from 20 bull testes and were then supplemented with 0.1 mM vitamin E, 5.0 mM vitamin C, 100.0 IU/mL SOD, and 100.0 μg/mL catalase alone, or in a combination. The control treatment contained no addition. After supplementation, samples were frozen and stored in liquid nitrogen. The sperm parameters including motility, progressive motility, viability, acrosome integrity, plasma membrane integrity, kinematics and DNA damage were evaluated following the thawing process. Results: Vitamin E alone significantly increased the parameters of acrosome and membrane integrity compared to the control treatment (P&lt;0.05). While compared to the control treatment, vitamin C had no improvement effect on sperm characteristics except for membrane integrity. Treatment of vitamin E+vitamin C had a significant improvement in total motility, progressive motility, viability, membrane and acrosome integrity compared to the control and other treatments (P&lt;0.05). Compared to the control treatment, addition of SOD or catalase alone significantly improved the percentages of total motility, progressive motility, viability, membrane and acrosome integrity (P&lt;0.05). Furthermore, SOD+catalase significantly increased total motility, progressive motility, viability, acrosome and membrane integrity characteristics compared to the catalase treatment (P&lt;0.05). Vitamin E alone, vitamin E+vitamin C, and SOD in diluents decreased DNA damages and thereby improved the rate of intact sperm heads. Conclusions: Addition of 100.0 IU/mL SOD alone and 0.1 mM vitamin E+5.0 mM vitamin C, and also 5.0 mM vitamin C+100 μg/mL catalase in a combination improves the quality of cryopreserved bull epididymal sperm and could be used for cryopreservation.

Effect of catalase on lipid oxidation and flavor substances of α- instant rice during storage

Lipid oxidation is one of the important factors affecting the quality of α-instant rice. In this study, α- instant rice was detected with hydrogen peroxide value (POV), malondialdehyde value (MDA) and fatty acid value (FAV), colorimeter, electronic nose and HS-SPME GC/MS before and after storage. As well as, the effect of catalase treatment on the quality of α-instant rice during storage was investigated The results showed that the content of MDA in α-instant rice decreased by 41.4% in the late stage of the accelerated storage test (21 days), which was 4.3% lower than that of α-instant rice treated with BHT. At the same time, catalase had more advantages in maintaining the whiteness and aroma of α-instant rice, and inhibiting the aldehydes, ketones, hydrocarbons and various volatile odor substances produced by lipid oxidation of α-instant rice. Therefore, catalase, as a natural substitute for synthetic antioxidants, has great potential in the antioxidation of convenience foods.