Optimization of physical factors affecting the production of thermo-stable organic solvent-tolerant protease from a newly isolated halo tolerant Bacillus subtilis strain Rand

<p>Abstract</p> <p>Background</p> <p>Many researchers have reported on the optimization of protease production; nevertheless, only a few have reported on the optimization of the production of organic solvent-tolerant proteases. Ironically, none has reported on thermostable organic solvent-tolerant protease to date. The aim of this study was to isolate the thermostable organic solvent-tolerant protease and identify the culture conditions which support its production. The bacteria of genus <it>Bacillus </it>are active producers of extra-cellular proteases, and the thermostability of enzyme production by <it>Bacillus </it>species has been well-studied by a number of researchers. In the present study, the <it>Bacillus subtilis </it>strain Rand was isolated from the contaminated soil found in Port Dickson, Malaysia.</p> <p>Results</p> <p>A thermostable organic solvent-tolerant protease producer had been identified as <it>Bacillus subtilis </it>strain Rand, based on the 16S rRNA analysis conducted, as well as the morphological characteristics and biochemical properties. The production of the thermostable organic solvent-tolerant protease was optimized by varying various physical culture conditions. Inoculation with 5.0% (v/v) of (AB₆₀₀= 0.5) inoculum size, in a culture medium (pH 7.0) and incubated for 24 h at 37°C with 200 rpm shaking, was the best culture condition which resulted in the maximum growth and production of protease (444.7 U/ml; 4042.4 U/mg). The Rand protease was not only stable in the presence of organic solvents, but it also exhibited a higher activity than in the absence of organic solvent, except for pyridine which inhibited the protease activity. The enzyme retained 100, 99 and 80% of its initial activity, after the heat treatment for 30 min at 50, 55, and 60°C, respectively.</p> <p>Conclusion</p> <p>Strain Rand has been found to be able to secrete extra-cellular thermostable organic solvent-tolerant protease into the culture medium. The protease exhibited a remarkable stability towards temperature and organic solvent. This unique property makes it attractive and useful to be used in industrial applications.</p

Fusion of locally linear embedding and principal component analysis for face recognition (FLLEPCA)

We proposed a novel approach for face recognition to address the challenging task of recognition using a fusion of nonlinear dimensional reduction; Locally Linear Embedding (LLE) and Principal Component Analysis (PCA) LLE computes a compact representation of high dimensional data combining the major advantages of linear methods, With the advantages of nonlinear approaches which is flexible to learn a broad of class on nonlinear manifolds. The application of LLE, however, is limited due to its lack of a parametric mapping between the observation and the low-dimensional output. In addition, the revealed underlying manifold can only be observed subjectively. To overcome these limitations, we propose our method for recognition by fusion of LLE and Principal Component Analysis (FLLEPCA) and validate their efficiency. Experiments on CMU AMP Face EXpression Database and JAFFE databases show the advantages of our proposed novel approach

Antimicrobial and cytotoxic comparative study of different extracts of Omani and Sudanese Gum acacia

Gum acacia, known as Gum Arabic in Oman is widely grown all over the tropical countries including Gulf region. The antimicrobial and cytotoxic activities of different polarity organic extracts of Omani and Sudanese Gum acacia latex has been investigated in this study using maceration method. Both Omani and Sudanese Gum acacia latex samples were used to prepare different fractions using various organic solvents. The antimicrobial activity of different organic extracts was determined through disc diffusion method against clinically isolated bacterial strains. The isolated pathogenic bacterial strain are Gram (+) Staphylococcus aureus (S. aureus, Code No. 659), Gram (−) Escherichia coli (E. coli, Code No. 846), Gram (−) Escherichia coli (E. coli, Code No. 683) and Gram (−) Klebsiella pneumoniae (Code No. 684). The antibiotic levofloxacin and dimethyl sulphoxide (DMSO) were used as positive and negative controls. The cytotoxic activity of the above mentioned organic extracts was determined by brine shrimp lethality method (BSL). Both latex samples of various polarity organic extracts at different concentrations showed antimicrobial activity against the isolated human bacterial strains with an inhibition range of 0–15 mm. However, both latex samples did not reveal a significant cytotoxic activity at any concentration. In conclusion, the organic extracts from both types of Gum acacia (Omani and Sudanese) represent a good source of natural antibiotic for the treatment of various infectious diseases