Palm kernel cake (PKC) has been largely produced in Malaysia as one of the cheap and abundant agro-waste by-products from the palm oil industry and it contains high fiber (mannan) content. The present study aimed to produce β-mannanase by Bacillus subtilis ATCC11774 via optimization of the medium composition using palm kernel cake as substrate in semi-solid fermentation. The fermentation nutrients such as PKC, peptone, yeast extract, sodium chloride, magnesium sulphate (MgSO2), initial culture pH and temperature were screened using a Plackett-Burman design. The three most significant factors identified, PKC, peptone and NaCl, were further optimized using central composite design (CCD), a response surface methodology (RSM) approach, where yeast extract and MgSO2 were fixed as a constant factor. The maximum β-mannanase activity predicted by CCD under the optimum medium composition of 16.50 g/L PKC, 19.59 g/L peptone, 3.00 g/L yeast extract, 2.72 g/L NaCl and 0.2 g/L MgSO2 was 799 U/mL. The validated β-mannanase activity was 805.12 U/mL, which was close to the predicted β-mannanas activity. As a comparison, commercial media such as nutrient broth, M9 and Luria bertani were used for the production of β-mannanase with activities achieved at 204.16 ± 9.21 U/mL, 50.32 U/mL and 88.90 U/mL, respectively. The optimized PKC fermentation medium was four times higher than nutrient broth. Hence, it could be a potential fermentation substrate for the production of β-mannanase activity by Bacillus subtilis ATCC11774.
Matched MeSH terms: Bacillus subtilis/growth & development
Thermostable lipase produced by a genotypically identified extremophilic Bacillus subtilis NS 8 was purified 500-fold to homogeneity with a recovery of 16% by ultrafiltration, DEAE-Toyopearl 650M and Sephadex G-75 column. The purified enzyme showed a prominent single band with a molecular weight of 45 kDa. The optimum pH and temperature for activity of lipase were 7.0 and 60°C, respectively. The enzyme was stable in the pH range between 7.0 and 9.0 and temperature range between 40 and 70°C. It showed high stability with half-lives of 273.38 min at 60°C, 51.04 min at 70°C and 41.58 min at 80°C. The D-values at 60, 70 and 80°C were 788.70, 169.59 and 138.15 min, respectively. The enzyme's enthalpy, entropy and Gibb's free energy were in the range of 70.07-70.40 kJ mol(-1), -83.58 to -77.32 kJ mol(-1)K(-1) and 95.60-98.96 kJ mol(-1), respectively. Lipase activity was slightly enhanced when treated with Mg(2+) but there was no significant enhancement or inhibition of the activity with Ca(2+). However, other metal ions markedly inhibited its activity. Of all the natural vegetable oils tested, it had slightly higher hydrolytic activity on soybean oil compared to other oils. On TLC plate, the enzyme showed non-regioselective activity for triolein hydrolysis.
Matched MeSH terms: Bacillus subtilis/growth & development
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
A number of novel 5-substituted-2-((6-bromo-3,4-methylenedioxybenzyl)thio)-1,3,4-Oxadiazole derivatives (6a-l) have been synthesized to evaluate their antibacterial activity. Using aryl/aralkyl carboxylic acids (1a-l) as precursors, 5-substituted-1,3,4-Oxadiazol-2-thiols (4a-l) were yielded in good amounts. The derivatives, 4a-l, were subjected to electrophilic substitution reaction on stirring with 6-bromo-3,4-methylenedioxybenzyl chloride (5) in DMF to synthesize the required compounds. All the synthesized molecules were well characterized by IR, 1H-NMR, 13C-NMR and EIMS spectral data and evaluated for antibacterial activity against some bacterial strains of Gram-bacteria. The molecule, 6d, demonstrated the best activity among all the synthesized molecules exhibiting weak to moderate inhibition potential.
Matched MeSH terms: Bacillus subtilis/growth & development
A series of N'-(substituted benzylidene)-2-(benzo[d]oxazol-3(2H)-yl)acetohydrazide derivatives was synthesized and evaluated for its in vitro antimicrobial and anticancer activities. Antimicrobial activity results revealed that compound 12 was found to be the most potent antimicrobial agent. Results of anticancer study indicated that the synthesized compounds exhibited average anticancer potential. Compound 7 (IC 50 =3.12 µM) and compound 16 (IC 50 =2.88 µM) were found to be most potent against breast cancer (MCF7) cell lines. In conclusion, compound 12 and 16 have the potential to be selected as lead compound for the developing of novel antimicrobial and anticancer agents respectively.
Matched MeSH terms: Bacillus subtilis/growth & development
A total of 32 lactic acid bacteria (LAB) were isolated from 13 honey samples commercially marketed in Malaysia, 6 strains identified as Lactobacillus acidophilus by API CHL50. The isolates had antibacterial activities against multiple antibiotic resistant's Staphylococcus aureus (25 to 32 mm), Staphylococcus epidermis (14 to 22 mm) and Bacillus subtilis (12 to 19 mm) in the agar overlay method after 24 h incubation at 30 °C. The crude supernatant was heat stable at 90 °C and 121 °C for 1 h. Treatment with proteinase K and RNase II maintained the antimicrobial activity of all the supernatants except sample H006-A and H010-G. All the supernatants showed antimicrobial activities against target bacteria at pH 3 and pH 5 but not at pH 6 within 72 h incubation at 30 °C. S. aureus was not inhibited by sample H006-A isolated from Libyan honey and sample H008-D isolated from Malaysian honey at pH 5, compared to supernatants from other L. acidophilus isolates. The presence of different strains of L. acidophilus in honey obtained from different sources may contribute to the differences in the antimicrobial properties of honey.
Matched MeSH terms: Bacillus subtilis/growth & development
Bacillus strain NS 8, a lipase-producing bacterium isolated from a Malaysian hot spring, is able to tolerate a broad range of temperature and pH, which makes it beneficial for this study. It generated PCR products with molecular weight of 1,532 bp, and the 16S rRNA sequence analysis identified it as Bacillus subtilis with accession number AB110598. It showed a 71% similarity index with B. subtilis using Biolog Microstation System. Its lipase production was optimized using a shake flask system by changing the physical (agitation speed, pH and temperature) and nutritional (nitrogen, carbon and minerals) factors. The most suitable combination of the basal medium for lipase production was 2.5% olive oil (carbon), 1.5% peptone (nitrogen), 0.1% MgSO(4) (mineral) at an optimum temperature of 50°C, pH 7.5 and 150 rpm agitation, giving an enzyme yield of 4.23 U/ml. Statistical optimization using response surface methodology was carried out. An optimum lipase production of 5.67 U/ml was achieved when olive oil concentration of 3%, peptone 2%, MgSO(4)·7H(2)O 0.2% and an agitation rate of 200 rpm were combined. Lipase production was further carried out inside a 2-liter bioreactor, which yielded an enzyme activity of 14.5 U/ml after 15 h of incubation.
Several novel 1-[2-(1H-tetrazol-5-yl) ethyl]-1H-benzo[d][1,2,3]triazoles (3a-h) have been synthesized by the condensation of 1-[2-(1H-tetrazol-5-yl)-ethyl]-1H-benzotriazole (2) and appropriate acid chlorides. 1-[2-(1H-tetrazol-5-yl)-ethyl]-1H-benzotriazole (2) was synthesized by reacting 3-(1H-benzo[d][1,2,3]triazol-1-yl)propanenitrile with sodium azide and ammonium chloride in the presence of dimethylformamide. The synthesized compounds were characterized by IR and PMR analysis. The titled compounds were evaluated for their in-vitro antibacterial and antifungal activity by the cup plate method and anticonvulsant activity evaluated by the maximal electroshock induced convulsion method in mice. All synthesized compounds exhibited moderate antibacterial activity against Bacillus subtilis and moderate antifungal activity against Candida albicans. Compounds 5-(2-(1H-benzo[d][1,2,3]triazo-1-yl)ethyl)-1H-tetrazol-1-yl)(4-aminophenyl)methanone 3d and 5-(2-(1 H-benzo[d][1,2,3]triazo-1-yl)ethyl)-1H-tetrazol-1-yl)(2-aminophenyl)methanone 3e elicited excellent anticonvulsant activity.
Matched MeSH terms: Bacillus subtilis/growth & development