Displaying publications 261 - 280 of 367 in total

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  1. Fulltext Antibacterial Activity and Mode of Action of β-caryophyllene on Bacillus cereus
    Moo CL, Yang SK, Osman MA, Yuswan MH, Loh JY, Lim WM, et al.
    Pol J Microbiol, 2020;69:1-6.
    PMID: 32162852 DOI: 10.33073/pjm-2020-007
    Natural products such as essential oils (EOs) are secondary metabolites that can be obtained from either plant or animal sources or produced by microorganisms. Much attention has been given to exploring the use of secondary metabolites as natural antibacterial agents. This study investigates the antibacterial activity and mechanism of β-caryophyllene, a compound that can be found in various EOs, against Bacillus cereus. The minimum inhibitory concentration of β-caryophyllene against B. cereus was 2.5% (v/v), whereas killing kinetics of β-caryophyllene at minimum inhibitory concentration recorded complete bactericidal activity within 2 hours. Zeta-potential measurement in the cells treated with half the minimum inhibitory concentration of β-caryophyllene at 1.25% (v/v) showed an increase in the membrane permeability surface charge to -3.98 mV, compared to untreated cells (-5.46 mV). Intracellular contents leakage of UV-absorbing materials was detected in the cells treated with β-caryophyllene. Additionally, β-caryophyllene does not interfere with the efflux activity of B. cereus via the ethidium bromide influx/efflux activity. The results revealed that β-caryophyllene was able to alter membrane permeability and integrity of B. cereus, leading to membrane damage and intracellular content leakage, which eventually caused cell death.

    Natural products such as essential oils (EOs) are secondary metabolites that can be obtained from either plant or animal sources or produced by microorganisms. Much attention has been given to exploring the use of secondary metabolites as natural antibacterial agents. This study investigates the antibacterial activity and mechanism of β-caryophyllene, a compound that can be found in various EOs, against Bacillus cereus. The minimum inhibitory concentration of β-caryophyllene against B. cereus was 2.5% (v/v), whereas killing kinetics of β-caryophyllene at minimum inhibitory concentration recorded complete bactericidal activity within 2 hours. Zeta-potential measurement in the cells treated with half the minimum inhibitory concentration of β-caryophyllene at 1.25% (v/v) showed an increase in the membrane permeability surface charge to –3.98 mV, compared to untreated cells (–5.46 mV). Intracellular contents leakage of UV-absorbing materials was detected in the cells treated with β-caryophyllene. Additionally, β-caryophyllene does not interfere with the efflux activity of B. cereus via the ethidium bromide influx/efflux activity. The results revealed that β-caryophyllene was able to alter membrane permeability and integrity of B. cereus, leading to membrane damage and intracellular content leakage, which eventually caused cell death.

    Matched MeSH terms: Bacillus cereus
  2. Fulltext Effect of dried and extrudate of bitter gourd fruit on epithelial microflora in raw chicken legs meat
    Rukayadi, Y., Abdulkarim, S.M., Sulaiman, R., Abdelkarim, H.
    International Food Research Journal, 2017;24(5):2253-2258.
    MyJurnal
    Plants have been used recently to eliminate bacterial growth in food products. This study was undertaken to test the in vitro sanitizing effect of crude extract from bitter gourd (BG) fruit on the growth of native microorganisms in raw chicken leg meat. Hot air dried BG and extrudate extracts at 1% concentration and exposure times of (5, 10 and 15 min) were used to treat the samples using dilution method. Results showed that BG extrudate had a slightly stronger bactericidal activity against the microflora than the B.G. hot air drying treatment, especially, on E. coli at all exposure time. Overall, there is no significant difference between the treatments; Total Plate Count (TPC), Escherichia coli, Bacillus cereus, Staphylococcus aureus. The best reduction time of microflora by hot air dried extract was at (15 min) except for B. cereus was at (5 min) and for extrudate extract was at (5 min) except for E. coli was at (10 min). In conclusion, bitter gourd extract could be used as an important natural sanitizer for rinsing raw food matrials such chicken meat.
    Matched MeSH terms: Bacillus cereus
  3. Role of extremophilic Bacillus cereus KH1 and its lipopeptide in treatment of organic pollutant in wastewater
    Nor FHM, Abdullah S, Ibrahim Z, Nor MHM, Osman MI, Al Farraj DA, et al.
    Bioprocess Biosyst Eng, 2023 Mar;46(3):381-391.
    PMID: 35779113 DOI: 10.1007/s00449-022-02749-1
    An effective biosurfactant producer and extremophiles bacteria, Bacillus cereus KH1, was isolated from textile effluent and the biosurfactant was produced using molasses as the sole carbon source. Growth parameters such as pH, temperature, salinity and concentration of molasses were optimised for decolourising the textile effluent with 24-h incubation. The biosurfactant property of B. cereus KH1 was evaluated based on haemolytic activity, oil displacement technique, drop-collapsing test and emulsification index. The results of the produced biosurfactant showed a positive reaction in haemolytic activity, oil displacement technique, drop-collapsing test and exhibiting a 67% emulsification index. The cell-free broth was stable in 40 °C pH 7, 7% salinity and 7% molasses. Thin-Layer Chromatography and Fourier Transform Infrared Spectroscopy analysis revealed that the biosurfactant was a lipopeptide with a yield 2.98 g L-1. These findings proved the synergistic action of B. cereus KH1 with lipopeptide biosurfactant may accelerated the decolourisation efficiency to 87%.
    Matched MeSH terms: Bacillus cereus
  4. Fulltext Challenges and Opportunities of Biocoagulant/Bioflocculant Application for Drinking Water and Wastewater Treatment and Its Potential for Sludge Recovery
    Kurniawan SB, Abdullah SRS, Imron MF, Said NSM, Ismail N', Hasan HA, et al.
    Int J Environ Res Public Health, 2020 Dec 12;17(24).
    PMID: 33322826 DOI: 10.3390/ijerph17249312
    The utilization of metal-based conventional coagulants/flocculants to remove suspended solids from drinking water and wastewater is currently leading to new concerns. Alarming issues related to the prolonged effects on human health and further pollution to aquatic environments from the generated nonbiodegradable sludge are becoming trending topics. The utilization of biocoagulants/bioflocculants does not produce chemical residue in the effluent and creates nonharmful, biodegradable sludge. The conventional coagulation-flocculation processes in drinking water and wastewater treatment, including the health and environmental issues related to the utilization of metal-based coagulants/flocculants during the processes, are discussed in this paper. As a counterpoint, the development of biocoagulants/bioflocculants for drinking water and wastewater treatment is intensively reviewed. The characterization, origin, potential sources, and application of this green technology are critically reviewed. This review paper also provides a thorough discussion on the challenges and opportunities regarding the further utilization and application of biocoagulants/bioflocculants in water and wastewater treatment, including the importance of the selection of raw materials, the simplification of extraction processes, the application to different water and wastewater characteristics, the scaling up of this technology to a real industrial scale, and also the potential for sludge recovery by utilizing biocoagulants/bioflocculants in water/wastewater treatment.
    Matched MeSH terms: Bacillus; Paenibacillus
  5. Fulltext In Vitro Pharmacological Activities and GC-MS Analysis of Different Solvent Extracts of Lantana camara Leaves Collected from Tropical Region of Malaysia
    Swamy MK, Sinniah UR, Akhtar MS
    Evid Based Complement Alternat Med, 2015;2015:506413.
    PMID: 26783409 DOI: 10.1155/2015/506413
    We investigated the effect of different solvents (ethyl acetate, methanol, acetone, and chloroform) on the extraction of phytoconstituents from Lantana camara leaves and their antioxidant and antibacterial activities. Further, GC-MS analysis was carried out to identify the bioactive chemical constituents occurring in the active extract. The results revealed the presence of various phytocompounds in the extracts. The methanol solvent recovered higher extractable compounds (14.4% of yield) and contained the highest phenolic (92.8 mg GAE/g) and flavonoid (26.5 mg RE/g) content. DPPH radical scavenging assay showed the IC50 value of 165, 200, 245, and 440 μg/mL for methanol, ethyl acetate, acetone, and chloroform extracts, respectively. The hydroxyl scavenging activity test showed the IC50 value of 110, 240, 300, and 510 μg/mL for methanol, ethyl acetate, acetone, and chloroform extracts, respectively. Gram negative bacterial pathogens (E. coli and K. pneumoniae) were more susceptible to all extracts compared to Gram positive bacteria (M. luteus, B. subtilis, and S. aureus). Methanol extract had the highest inhibition activity against all the tested microbes. Moreover, methanolic extract of L. camara contained 32 bioactive components as revealed by GC-MS study. The identified major compounds included hexadecanoic acid (5.197%), phytol (4.528%), caryophyllene oxide (4.605%), and 9,12,15-octadecatrienoic acid, methyl ester, (Z,Z,Z)- (3.751%).
    Matched MeSH terms: Bacillus subtilis
  6. Fulltext GC-MS Based Metabolite Profiling, Antioxidant and Antimicrobial Properties of Different Solvent Extracts of Malaysian Plectranthus amboinicus Leaves
    Swamy MK, Arumugam G, Kaur R, Ghasemzadeh A, Yusoff MM, Sinniah UR
    Evid Based Complement Alternat Med, 2017;2017:1517683.
    PMID: 28424737 DOI: 10.1155/2017/1517683
    This study evaluates the phytochemistry, antioxidant, and antimicrobial effects of Plectranthus amboinicus leaves extracted in different solvents. The methanol extract contained the highest total phenolic (94.37 ± 1.24 mg GAE/g) and flavonoid contents (26.90 ± 1.35 mg RE/g) and exhibited the highest DPPH scavenging activity (90.13 ± 3.32%) followed by the acetone extract (80.23 ± 3.26%) at 500 μg/mL concentration. Similarly, the highest ferric ion reduction potential (849.63 ± 30.95 μM of Fe (II)/g dry weight) was exhibited by the methanol extract followed by the acetone extract (695.92 ± 25.44 μM of Fe (II)/g dry weight). The methanol extract showed greater antimicrobial activity against all the tested pathogens (Bacillus subtilis, Methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans). However, both hexane and acetone extracts failed to inhibit E. coli. S. aureus and C. albicans were more susceptible to all the extracts. Further, GC-MS analysis confirmed the occurrence of a total 46 phytocompounds in different solvent extracts. Some of the major compounds included carvacrol (37.7%), tetracontane (16.6%), squalene (15.6%), tetrapentacontane (13.7%), and Phytol (12.9%). In conclusion, extraction solvents influenced the recovery of phytocompounds and the highest pharmacological activities of the methanol extract could be correlated to the presence of additional bioactive compounds.
    Matched MeSH terms: Bacillus subtilis
  7. Effects of Methanol Extract of Wedelia chinensis Osbeck (Asteraceae) Leaves against Pathogenic Bacteria with Emphasise on Bacillus cereus
    Darah I, Lim SH, Nithianantham K
    Indian J Pharm Sci, 2013 Sep;75(5):533-9.
    PMID: 24403653
    The antibacterial activity of the methanol extract of Wedelia chinensis leave was studied and tested against three pathogenic Gram positive bacteria (Bacillus cereus, B. subtilis and Stapylococcus aureus) and three pathogenic Gram negative bacteria (Escherichia coli, Proteus rettgeri and Pseudomonas aeruginosa) by the disk diffusion assay and broth dilution methods. The extract exhibited favourable antibacterial activity against the bacterial cells but was more potent against Gram positive bacteria with the minimum inhibition concentration of 3.12 to 6.25 mg/ml compared to the Gram negative bacteria which had minimum inhibition concentration values of 25 mg/ml. The time-kill study suggested that the extract possessed bactericidal properties at higher concentrations and eradicated the growth of bacterial cells. The major abnormalities occurred to the bacterial cells after exposed to the extract were complete alterations in their morphology and collapsed of the cells beyond repair. The methanol extract of W. chinensis may be an effective antibacterial agent to treat bacterial infections.
    Matched MeSH terms: Bacillus cereus
  8. The Effects of Bacillus subtilis QST713 and β-mannanase on growth performance, intestinal barrier function, and the gut microbiota in weaned piglets
    Liu J, Ma X, Zhuo Y, Xu S, Hua L, Li J, et al.
    J Anim Sci, 2023 Jan 03;101.
    PMID: 37583344 DOI: 10.1093/jas/skad257
    We investigated the effects of different Bacillus subtilis QST713 doses and a B. subtilis QST713 and β-mannanase mix on growth performance, intestinal barrier function, and gut microbiota in weaned piglets. In total, 320 healthy piglets were randomly assigned to four groups: 1) control group (basal diet), 2) BS100 group (basal diet plus 100 mg/kg B. subtilis QST713), 3) BS200 group (basal diet plus 200 mg/kg B. subtilis QST713), and 4) a BS100XT group (basal diet plus 100 mg/kg B. subtilis QST713 and 150 mg/kg β-mannanase). The study duration was 42 d. We showed that feed intake in weaned piglets on days 1 to 21 was increased in group BS100 (P < 0.05), and that the feed conversion ratio in group BS100XT animals decreased throughout the study (P < 0.05). In terms of microbial counts, the BS100XT group showed reduced Escherichia coli and Clostridium perfringens numbers on day 21 (P < 0.05). Moreover, no significant α-diversity differences were observed across all groups during the study (P > 0.05). However, principal coordinates analysis indicated clear separations in bacterial community structures across groups (analysis of similarities: P < 0.05) on days 21 and 42. Additionally, E-cadherin, occludin, and zonula occludens-1 (ZO-1) expression in piglet feces increased (P < 0.05) by adding B. subtilis QST713 and β-mannanase to diets. Notably, this addition decreased short-chain fatty acid concentrations. In conclusion, B. subtilis QST713 addition or combined B. subtilis QST713 plus β-mannanase effectively improved growth performance, intestinal barrier function, and microbial balance in weaned piglets.
    Matched MeSH terms: Bacillus subtilis
  9. Fulltext Dilute acid-assisted microbubbles-mediated ozonolysis of Eucheuma denticulatum phycocolloid for biobased L-lactic acid production
    Tong KTX, Tan IS, Foo HCY, Hadibarata T, Lam MK, Wong MK
    Bioresour Technol, 2024 Aug;406:131082.
    PMID: 38972432 DOI: 10.1016/j.biortech.2024.131082
    Biobased L-lactic acid (L-LA) appeals to industries; however, existing technologies are plagued by limited productivity and high energy consumption. This study established an integrated process for producing macroalgae-based L-LA from Eucheuma denticulatum phycocolloid (EDP). Dilute acid-assisted microbubbles-mediated ozonolysis (DAMMO) was selected for the ozonolysis of EDP to optimize D-galactose recovery. Through single-factor optimization of DAMMO treatment, a maximum D-galactose recovery efficiency (59.10 %) was achieved using 0.15 M H2SO4 at 80 °C for 75 min. Fermentation with 3 % (w/v) mixed microbial cells (Bacillus coagulans ATCC 7050 and Lactobacillus acidophilus-14) and fermented residues achieved a 97.67 % L-LA yield. Additionally, this culture approach was further evaluated in repeated-batch fermentation and showed an average L-LA yield of 93.30 %, providing a feasible concept for macroalgae-based L-LA production.
    Matched MeSH terms: Bacillus coagulans
  10. Fulltext Mobile Phones: A Possible Vehicle of Bacterial Transmission in a Higher Learning Institution in Malaysia
    Hikmah N', Anuar TS
    Malays J Med Sci, 2020 Mar;27(2):151-158.
    PMID: 32788850 MyJurnal DOI: 10.21315/mjms2020.27.2.15
    Background: Mobile phones (MPs) have become one of the most indispensable accessories in social and professional life. Though they offer plenty of benefits, MPs are prolific breeding grounds for infectious pathogens in communities. Thus, the aim of this study was to identify the prevalence of bacterial contamination and determine antimicrobial susceptibility pattern of Staphylococcus aureus (S. aureus) from MPs.

    Methods: A cross-sectional study was conducted from March to July 2019 on 126 students and 37 laboratory staff/clinical instructors' MPs from the Faculty of Health Sciences, Universiti Teknologi MARA, Malaysia by a simple random sampling technique. Along with the questionnaire, a swab sample from each participant's MPs was collected and transported to the microbiology laboratory for bacterial culture as per standard microbiological procedures and antimicrobial susceptibility test by the disc diffusion technique. Data were analysed by the Statistical Package for Social Sciences Programme version 24.

    Results: All of the tested MPs were contaminated with either single or mix bacterial agents. Bacillus spp. (74.8%), coagulase-negative staphylococci (CoNS; 47.9%) and S. aureus (20.9%) were the most predominant bacterial isolates, whilst the least isolate was Proteus vulgaris (P. vulgaris) (2.5%). Oxacillin resistance was seen in 5.9% of S. aureus isolate. A comparison of bacteria type and frequency among gender showed a significant difference with P. vulgaris (P = 0.003) and among profession showed a significant difference with S. aureus (P = 0.004).

    Conclusion: The present study indicates that MPs can serve as a vector for both pathogenic and non-pathogenic organisms. Therefore, full guidelines about restricting the use of MPs in laboratory environments, hand hygiene and frequent decontamination of MPs are recommended to limit the risk of cross-contamination and healthcare-associated infections caused by MPs.

    Matched MeSH terms: Bacillus
  11. Fulltext Preliminary screening of endophytic fungi from medicinal plants in malaysia for antimicrobial and antitumor activity
    Radu S, Kqueen CY
    Malays J Med Sci, 2002 Jul;9(2):23-33.
    PMID: 22844221 MyJurnal
    The screening of antimicrobial activity against Gram-positive bacteria, Gram-negative bacteria, yeast and fungi was carried out on isopropanol extracts prepared from 121 isolates of endophytic fungi isolated from medicinal plants in Malaysia. Sensitivity was found to vary among the microorganisms. Bacillus subtilis, Saccharomyces cerevisiae and Alternaria sp. were susceptible to extracts from three, two and two isolates of endophytic fungi, respectively. None were found effective against Salmonella typhimurium. Sixteen endophytic fungal isolates tested were also found to exhibit antitumor activity in the yeast cell-based assay.
    Matched MeSH terms: Bacillus subtilis
  12. Fulltext A convenient method for the synthesis of (prop-2-ynyloxy)benzene derivatives via reaction with propargyl bromide, their optimization, scope and biological evaluation
    Batool T, Rasool N, Gull Y, Noreen M, Nasim FU, Yaqoob A, et al.
    PLoS One, 2014;9(12):e115457.
    PMID: 25545159 DOI: 10.1371/journal.pone.0115457
    A highly convenient method has been developed for the synthesis of (prop-2-ynyloxy) benzene and its derivatives. Differently substituted phenol and aniline derivatives were allowed to react with propargyl bromide in the presence of K2CO3 base and acetone as solvent. The compounds were synthesized in good yields (53-85%). Low cost, high yields and easy availability of compounds helped in the synthesis. Electron withdrawing groups favor the formation of stable phenoxide ion thus in turn favors the formation of product while electron donating groups do not favor the reaction. Phenol derivatives gave good yields as compared to that of aniline. As aprotic polar solvents favor SN2 type reactions so acetone provided best solvation for the reactions. K2CO3 was proved to be good for the synthesis. Antibacterial, Antiurease and NO scavenging activity of synthesized compounds were also examined. 4-bromo-2-chloro-1-(prop-2-ynyloxy)benzene 2a was found most active compound against urease enzyme with a percentage inhibition of 82.00±0.09 at 100 µg/mL with IC50 value of 60.2. 2-bromo-4-methyl-1-(prop-2-ynyloxy)benzene 2d was found potent antibacterial against Bacillus subtillus showing excellent inhibitory action with percentage inhibition of 55.67±0.26 at 100 µg/ml wih IC50 value of 79.9. Based on results, it can be concluded that some of the synthesized compounds may have potential antiurease and antibacterial effects against several harmful substances.
    Matched MeSH terms: Bacillus subtilis/drug effects
  13. Fulltext Optimization of a heterologous signal peptide by site-directed mutagenesis for improved secretion of recombinant proteins in Escherichia coli
    Jonet MA, Mahadi NM, Murad AM, Rabu A, Bakar FD, Rahim RA, et al.
    J. Mol. Microbiol. Biotechnol., 2012;22(1):48-58.
    PMID: 22456489 DOI: 10.1159/000336524
    A heterologous signal peptide (SP) from Bacillus sp. G1 was optimized for secretion of recombinant cyclodextrin glucanotransferase (CGTase) to the periplasmic and, eventually, extracellular space of Escherichia coli. Eight mutant SPs were constructed using site-directed mutagenesis to improve the secretion of recombinant CGTase. M5 is a mutated SP in which replacement of an isoleucine residue in the h-region to glycine created a helix-breaking or G-turn motif with decreased hydrophobicity. The mutant SP resulted in 110 and 94% increases in periplasmic and extracellular recombinant CGTase, respectively, compared to the wild-type SP at a similar level of cell lysis. The formation of intracellular inclusion bodies was also reduced, as determined by sodium dodecyl sulfate-polyacrylamyde gel electrophoresis, when this mutated SP was used. The addition of as low as 0.08% glycine at the beginning of cell growth improved cell viability of the E. coli host. Secretory production of other proteins, such as mannosidase, also showed similar improvement, as demonstrated by CGTase production, suggesting that the combination of an optimized SP and a suitable chemical additive leads to significant improvements of extracellular recombinant protein production and cell viability. These findings will be valuable for the extracellular production of recombinant proteins in E. coli.
    Matched MeSH terms: Bacillus/genetics*
  14. Purification and characterisation of antibacterial peptide-containing compound derived from palm kernel cake
    Tan YN, Ayob MK, Wan Yaacob WA
    Food Chem, 2013 Jan 1;136(1):279-84.
    PMID: 23017424 DOI: 10.1016/j.foodchem.2012.08.012
    Palm kernel cake (PKC), the most useful by-product resulted from palm kernel oil production. In this study, PKC-derived protein product was found suitable for use as an antimicrobial agent with potent antibacterial activity, particularly against Bacillus species, after enzymatic hydrolysis with alcalase. The hydrolysate was further purified by gel filtration chromatography. The purified fraction was found to have 14.63±0.70% (w/w) protein, a molecular mass of 2.4kDa and low hemolytic activity (<50% hemolysis of human erythrocytes at concentration of 1000μg/ml). The presence of lysine and the major component lauric acid derivative, as indicated by electrospray ionisation-mass spectrometry (ESI-MS) direct infusion and nuclear magnetic resonance (NMR) spectroscopy, may have contributed to the antibacterial effect of purified PKC fraction. This study suggests that the antibacterial PKC compound may be not a pure peptide but instead a peptide-containing compound high in lauric acid derivative.
    Matched MeSH terms: Bacillus/drug effects
  15. Fulltext Impact of larviciding with a Bacillus thuringiensis israelensis formulation, VectoBac WG, on dengue mosquito vectors in a dengue endemic site in Selangor State, Malaysia
    Lee HL, Chen CD, Masri SM, Chiang YF, Chooi KH, Benjamin S
    Southeast Asian J. Trop. Med. Public Health, 2008 Jul;39(4):601-9.
    PMID: 19058596
    The field bioefficacy of a wettable granule (WG) formulation of Bacillus thuringiensis israelensis (Bti), VectoBac WG (Bti strain AM65-52) against dengue vectors, Aedes aegypti and Ae albopictus; was evaluated in a suburban residential area (TST) and in a temporary settlement site (KB) in the state of Selangor, Malaysia. Pre-control ovitrap surveillance of the trial sites indicated a high population of both types of Aedes mosquitoes. The populations were monitored continuously by weekly ovitrapping. Bti was sprayed biweekly at a dosage of 500 g/ha by using a mist-blower. The spray application was targeted into outdoor larval habitats. If required, Bti formulation was also applied directly into indoor water-holding containers at 8 g/1,000 l. Based on ovitrap surveillance, a significant reduction in Aedes populations was evident 4 weeks after initiating the first Bti treatment. The ovitrap index (OI) and the larvae density decreased drastically in both trial sites. In TST, the indoor OI was significantly reduced from 57.50 +/- 7.50% to 19.13 +/- 5.49% (p<0.05), while the outdoor OI decreased from 38.89 +/- 11.11% to 15.36 +/- 5.93%. In KB, similarly, the OI was significantly reduced by more than half, from 66.66 +/- 6.67% to 30.26 +/- 2.99% (p< 0.05). In all cases, the reduction in OI was paralleled by reduction in larval density.
    Matched MeSH terms: Bacillus thuringiensis/growth & development*
  16. Isolation and mode of action of bacteriocin BacC1 produced by nonpathogenic Enterococcus faecium C1
    Goh HF, Philip K
    J Dairy Sci, 2015 Aug;98(8):5080-90.
    PMID: 26004828 DOI: 10.3168/jds.2014-9240
    Lactic acid bacteria are present in fermented food products and help to improve shelf life and enhance the flavor of the food. They also produce metabolites such as bacteriocins to prevent the growth of undesirable or pathogenic bacteria. In this study, Enterococcus faecium C1 isolated from fermented cow milk was able to produce bacteriocin BacC1 and inhibit the growth of selected food-spoilage bacteria. The bacteriocin was purified through 4 steps: ammonium sulfate precipitation, hydrophobic interaction column, a series of centrifugal steps, and finally reversed-phase HPLC. A membrane permeability test using SYTOX green dye (Invitrogen, Grand Island, NY) showed that the bacteriocin caused significant disruptions to the test bacterial membrane, as shown by transmission electron microscopy. The molecular weight of the BacC1 obtained from SDS-PAGE was around 10kDa, and N-terminal sequencing revealed a partial amino acid sequence of BacC1: GPXGPXGP. The bacterial strain was nonhemolytic and not antibiotic resistant. Therefore, it has high potential for application in the food industry as an antimicrobial agent to extend the shelf life of food products.
    Matched MeSH terms: Bacillus cereus/physiology*
  17. Molten globule-triggered inactivation of a thermostable and solvent stable lipase in hydrophilic solvents
    Hamid TH, Rahman RN, Salleh AB, Basri M
    Protein J, 2010 May;29(4):290-7.
    PMID: 20509044 DOI: 10.1007/s10930-010-9251-7
    The use of lipase in hydrophilic solvent is usually hampered by inactivation. The solvent stability of a recombinant solvent stable lipase isolated from thermostable Bacillus sp. strain 42 (Lip 42), in DMSO and methanol were studied at different solvent-water compositions. The enzymatic activities were retained in up to 45% v/v solvent compositions. The near-UV CD spectra indicated that tertiary structures were perturbed at 60% v/v and above. Far-UV CD in methanol indicated the secondary structure in Lip 42 was retained throughout all solvent compositions. Fluorescence studies indicated formations of molten globules in solvent compositions of 60% v/v and above. The enzyme was able to retain its secondary structures in the presence of methanol; however, there was a general reduction in beta-sheet and an increase in alpha-helix contents. The H-bonding arrangements triggered in methanol and DMSO, respectively, caused different forms of tertiary structure perturbations on Lip 42, despite both showing partial denaturation with molten globule formations.
    Matched MeSH terms: Bacillus/enzymology*
  18. Multi-dimensional zinc oxide (ZnO) nanoarchitectures as efficient photocatalysts: What is the fundamental factor that determines photoactivity in ZnO?
    Chang JS, Strunk J, Chong MN, Poh PE, Ocon JD
    J Hazard Mater, 2020 01 05;381:120958.
    PMID: 31416043 DOI: 10.1016/j.jhazmat.2019.120958
    While bulk zinc oxide (ZnO) is of non-toxic in nature, ZnO nanoarchitectures could potentially induce the macroscopic characteristics of oxidative, lethality and toxicity in the water environment. Here we report a systematic study through state-of-the-art controllable synthesis of multi-dimensional ZnO nanoarchitectures (i.e. 0D-nanoparticle, 1D-nanorod, 2D-nanosheet, and 3D-nanoflowers), and subsequent in-depth understanding on the fundamental factor that determines their photoactivities. The photoactivities of resultant ZnO nanoarchitectures were interpreted in terms of the photodegradation of salicylic acid as well as inactivation of Bacillus subtilis and Escherichia coli under UV-A irradiation. Photodegradation results showed that 1D-ZnO nanorods demonstrated the highest salicylic acid photodegradation efficiency (99.4%) with a rate constant of 0.0364 min-1. 1D-ZnO nanorods also exhibited the highest log reductions of B. subtilis and E. coli of 3.5 and 4.2, respectively. Through physicochemical properties standardisation, an intermittent higher k value for pore diameter (0.00097 min-1 per mm), the highest k values for crystallite size (0.00171 min-1 per nm) and specific surface area (0.00339 min-1 per m2/g) contributed to the exceptional photodegradation performance of nanorods. Whereas, the average normalised log reduction against the physicochemical properties of nanorods (i.e. low crystallite size, high specific surface area and pore diameter) caused the strongest bactericidal effect.
    Matched MeSH terms: Bacillus subtilis/growth & development
  19. Novel cross-linked enzyme aggregates of levanase from Bacillus lehensis G1 for short-chain fructooligosaccharides synthesis: Developmental, physicochemical, kinetic and thermodynamic properties
    Abd Rahman NH, Jaafar NR, Abdul Murad AM, Abu Bakar FD, Shamsul Annuar NA, Md Illias R
    Int J Biol Macromol, 2020 Sep 15;159:577-589.
    PMID: 32380107 DOI: 10.1016/j.ijbiomac.2020.04.262
    Short-chain fructooligosaccharides (scFOSs) can be produced from the levan hydrolysis using levanase. Levanase from Bacillus lehensis G1 (rlevblg1) is an enzyme that specifically converts levan to scFOSs. However, the use of free levanase presents a lack of stability and reusability, thus hindering the synthesis of scFOSs for continuous reactions. Here, CLEAs for rlevblg1 were prepared and characterized. Cross-linked levanase aggregates using glutaraldehyde (CLLAs-ga) and bovine albumin serum (CLLAs-ga-bsa) showed the best activity recovery of 92.8% and 121.2%, respectively. The optimum temperature of CLLAs-ga and CLLAs-ga-bsa was increased to 35 °C and 40 °C, respectively, from its free rlevblg1 (30 °C). At high temperature (50 °C), the half-life of CLLAs-ga-bsa was higher than that of free rlevblg1 and CLLAs-ga. Both CLLAs exhibited higher stability at pH 9 and pH 10. Hyperactivation of CLLAs-ga-bsa was achieved with an effectiveness factor of more than 1 and with improved catalytic efficiency. After 3 h reaction, CLLAs-ga-bsa produced the highest total scFOSs yield of 35.4% and total sugar of 60.4% per gram levan. Finally, the reusability of CLLAs for 8 cycles with more than 50% activity retained makes them as a potential synthetic catalyst to be explored for scFOSs synthesis.
    Matched MeSH terms: Bacillus/enzymology*
  20. Computational docking, molecular dynamics simulation and subsite structure analysis of a maltogenic amylase from Bacillus lehensis G1 provide insights into substrate and product specificity
    Manas NH, Bakar FD, Illias RM
    J Mol Graph Model, 2016 06;67:1-13.
    PMID: 27155296 DOI: 10.1016/j.jmgm.2016.04.004
    Maltogenic amylase (MAG1) from Bacillus lehensis G1 displayed the highest hydrolysis activity on β-cyclodextrin (β-CD) to produce maltose as a main product and exhibited high transglycosylation activity on malto-oligosaccharides with polymerization degree of three and above. These substrate and product specificities of MAG1 were elucidated from structural point of view in this study. A three-dimensional structure of MAG1 was constructed using homology modeling. Docking of β-CD and malto-oligosaccharides was then performed in the MAG1 active site. An aromatic platform in the active site was identified which is responsible in substrate recognition especially in determining the enzyme's preference toward β-CD. Molecular dynamics (MD) simulation showed MAG1 structure is most stable when docked with β-CD and least stable when docked with maltose. The docking analysis and MD simulation showed that the main subsites for substrate stabilization in the active site are -2, -1, +1 and +2. A bulky residue, Trp359 at the +2 subsite was identified to cause steric interference to the bound linear malto-oligosaccharides thus prevented it to occupy subsite +3, which can only be reached by a highly bent glucose molecule such as β-CD. The resulted modes of binding from docking simulation show a good correlation with the experimentally determined hydrolysis pattern. The subsite structure generated from this study led to a possible mode of action that revealed how maltose was mainly produced during hydrolysis. Furthermore, maltose only occupies subsite +1 and +2, therefore could not be hydrolyzed or transglycosylated by the enzyme. This important knowledge has paved the way for a novel structure-based molecular design for modulation of its catalytic activities.
    Matched MeSH terms: Bacillus/enzymology*
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