The present review gives a survey of all the published methods along with their advantages and limitations. Traditional methods like thin layer chromatography, gas chromatography, liquid chromatography etc are still in use for this purpose. But some recent bio-analytical methods such as immunosensors, cell based sensors etc. have also gained equal importance. This article also overviews various electro-analytical methods and their applications as detection devices when combined with FIA and biosensors. Lastly nanoparticle based biosensors have also been discussed. The review concludes with futuristic approach to reduce the risks caused by pesticides. This scrutiny should provide concise evaluation of different techniques employed for pesticide detection in environmental samples.
Halophilic microorganisms are already in use for some biotechnological processes, such as commercial production of ß-carotene, polymers (polyhydroxyalkanoates and polysaccharides), enzymes, compatible solutes etc. Considering their commercial importance, food samples (crude salt crystals and raw mango pickle) were used for isolation of halotolerant microorganisms. Two bacterial isolates obtained from food samples were examined for their ability to survive under stressed conditions and their growth response in increasing levels of NaCl (1 to 15% w/v), pH (5.0 to 10.0) and temperature (10 to 70°C). The isolates were rod shaped Gram-positive, salt-tolerant, non-halophilic, nitrogen-fixing strains. Different sugars such as glucose, fructose, maltose, sucrose, xylose and lactose were used to check for acid and gas production. The organisms were studied for their ability to hydrolyse substrates such as casein, starch, gelatin, etc. These organisms (i) grew well in SM basal salt medium and nitrogen-free semi-solid LGI medium (ii) tolerated 10-15% salt concentration (iii) produced acid from D-glucose, D-fructose and sucrose and (iv) utilized glycerol and citrate as carbon source, and v) survived acidic (pH 4-5) and alkaline (pH 9-10) conditions. The results suggested that there is potential to improve their performance as sources of industrially important enzymes. On the basis of morphological attributes and biochemical characteristics the isolates belonged to the genus Bacillus. The results of partial sequencing of 16S rRNA also revealed that the isolates 1 and 2 are closely related to Bacillus subtilis subsp. subtilis NCIB 3610T (97.9% pairwise similarity) and Bacillus sonorensis NRRL B-23154T (99.8% pair-wise similarity) respectively. ACKNOWLEDGMENTSFig 3. Growth curves of isolates I and II. The cells were inoculated in the broth, incubated at 37°C, 120 rpm and their growth was determined by measuring the absorbance at 660 nm.a) In nutrient broth, b) In nutrient broth containing 10% and 15% NaCl, respectively. Arahal DR, Carmen Marquez M, Volcani BE, Schleifer KH, Ventosa A (1999) Bacillup. nov. a new moderately halophilic species from the Dead Sea. International Journal of Systematic Bacteriology 49, 521-530. Asha Devi NK, Balakrishnan K, Gopal R, Padmavathy S (2008) Bacillus clausii MB9 from the east coast regions of India: Isolation, biochemical characterization and antimicrobial activity. Current Science 95, 627-636. Ausubel FM, Rrent R, Kingston RE, Moore DD, Seidman JG, Smith JA, Struhl K (1987) Current Protocaol in Molecular Biology. Wiley, New York. Bordeleau LM, Prevost D (1994) Nodulation and nitrogen fixation in extreme environments. Plant and Soil 161, 115-125. Cavalcante VA, Dobereiner J (1988) A new acid-tolerant nitrogen fixing bacterium associated with sugar cane. Plant Soil 108, 23-31.
Out of the vast pool of enzymes, proteolytic enzymes from microorganisms are the most widely used in different industries such as detergent, food, peptide production etc. Several marine microorganisms are known to produce proteases with commercially desirable characteristics. We have isolated nine different cultures from marine samples of the Indian Ocean. All of them were i) motile ii) rod shaped iii) non spore forming iv) catalase and amylase positive v) able to grow in presence of 10 % NaCl. They produced acid from glucose, fructose and maltose and grew optimally at 30 0 C temperature and pH 7.0-8.0. None of them could grow above 45 0 C and below 15 0 C. Only one of them (MBRI 7) exhibited extracellular protease activity on skim milk agar plates. Based on 16S rDNA sequencing, it belonged to the genus Marinobacter (98% sequence similarity, 1201 bp). The cell free extract was used to study effects of temperature and pH on protease activity. The optimum temperature and pH for activity were found to be 40 0 C and 7.0 respectively. The crude enzyme was stable at temperature range of 30-80 0 C and pH 5.0-9.0. It retained 60 % activity at 80 0 C after 4 h and more than 70 % activity at 70 0 C after 1 h. D value was found to be 342 minutes and 78 minutes for 40 0 C and 80 0 C respectively. Interestingly the enzyme remained 50 % active at pH 9.0 after 1 h. Comparison with other proteases from different microbial sources indicated that the neutral protease from the halotolerant marine isolate MBRI 7 is a novel enzyme with high thermostability.
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