In vitro activity of methanolic extract from Lagerstroemia speciosa (Linn. ex. Murray) bark against pathogenic bacteria.

Crude methanolic extract of Lagerstroemia speciosa barks (Linn. ex. Murray) was subjected to antimicrobial screening including six Gram-positive and eight Gram-negative bacteria. The extract demonstrated significance antibacterial activities on 5 tested bacteria with the inhibition zone ranging from 10-15 mm. The minimum inhibitory concentration (MIC) of the extract was assessed by microdilution method. MIC value of Bacillus spizizenii ATCC6633, Bacillus cereus and Streptococcus coagulase-negative (SCN) was 0.25 mg/ml whilst Bacillus licheniformis and Acinetobacter anitratus showed MIC value of 0.50 mg/ml. However, only B. spizizenii ATCC6633 and B. licheniformis showed the minimum bactericidal concentration (MBC) value of 2.00 mg/ml and 1.00 mg/ml, respectively. The morphological changes of B.spizizenii ATCC6633 and A. anitratus with the treatment of the extract were observed under Scanning Electron Microscope (SEM). The results suggested that the L. speciosa methanolic extract had caused membrane structural degenerations of the cells and finally leading to cell-lysis.

Characterization of Solid State Fermentation Culture Conditions for Growth and Mananase Production by Aspergillus niger USM F4 on Rice Husk in Tray System.

Aim: The study evaluated various fermentation conditions for the production of mannanase. Place and Duration of Study: Industrial Biotechnology Research Laboratory (IBRL), School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia between May 2009 and September 2010. Methodology: Solid substrate fermentation was carried out in a shallow aluminum tray system (16 cm x 16 cm x 5 cm) for maximum mannanase production by Aspergillus niger USM F4 using rice husk as a substrate. Results: The maximum mannanase activity of 119.91 U/g substrate was achieved on the 6 days of cultivation when the optimized physical parameters were used (substrate thickness of 1.6 cm or equivalent to 80 g of 0.75 mm rice husk, moisture content to substrate ratio of 1:1 (w/v), cultivation temperature at room temperature (28±2ºC), inoculum size of 6x106 spores/ml and in static condition (no mixing during the fermentation process). The results showed an increment of about 30.79% of mannanase activity after the optimization (119.91 U/g substrate) compared to before optimization (91.68 U/g substrate). Conclusion: The results obtained from this study revealed that rice husk can be used as a substrate for mannanase production in solid state fermentation process.

Gallic acid: An anticandidal compound in hydrolysable tannin extracted from the barks of Rhizophora apiculata Blume.

A research was conducted to study the anticandidal compound of tannin extracted from the barks of a mangrove tree, Rhizophora apiculata Blume. Tannin obtained from the barks of Rhizophora apiculata Blume was further separated into condensed and hydrolysable tannins. A strong anticandidal activity was detected in the hydrolysable tannin, which exhibited minimal inhibitory concentration (MIC) of 6.25 mg/ml, and it was found to have yeastostatic activity at lower concentration (below MIC value) and yeastocidal activity at higher concentration (more than the MIC value). Furthermore, the isolation of the bioactive compound in hydrolysable tannin that responsible for the anticandidal activity was also determined using thin layer chromatography and high-performance liquid chromatography (HPLC). The results obtained confirmed that gallic acid was the bioactive compound that plays role in inhibiting and killing the Candida albicans cells.