Aflatoxin Contamination in Agricultural Commodities.

Aflatoxin is a naturally occurring Mycotoxin produced by Aspergillus flavus and Aspergillus parasiticus. Aspergillus flavus is common and widespread in nature and is most often found when certain grains are grown under stressful conditions such as draught. The mold occurs in soil, decaying vegetation, hay and grains undergoing microbiological deterioration and invades all types of organic substrates whenever and wherever the conditions are favourable for its growth. Favourable conditions include high moisture content and high temperature.The aflatoxin group is comprised of aflatoxin B1,B2,G1 and G2. In addition , aflatoxin M1 (AFM1), a hydroxylated metabolite of AFB1, is excreted in the milk of dairy cows consuming an AFB1-contaminated ration. Aflatoxin B1 a prototype of the aflatoxins, is widely recognized as the most potent hepato carcinogenic compound and along with other certain members of the group, possess additional toxic properties including mutagenicity, tetrogenicity, acute cellular toxicity and it suppresses the immune system. Aflatoxin contamination of food and feed has gained global significance as a result of its deleterious effects on human as well as animal health. The marketability of food products is adversely affected by aflatoxin contamination.

Isolation and Quantification of Aflatoxin from Aspergillus flavus Infected Stored Peanuts.

Isolates of Aspergillus infected Peanuts were separately grown on modified Czapek’s medium at 280 C and the metabolites were tested for aflatoxin by HPLC. Naturally infected peanuts collected from trader’s godown were tested for aflatoxins. Aflatoxins are considered to be one of the most dangerous contaminants in food and feeds. Aflatoxins are a special group of naturally occurring metabolites produced by the fungi aflatoxins B1, B2, G1 and G2 which contaminate a variety of agricultural food and feed products .Naturally infected peanuts from Aspergillus flavus stored at trader’s godown, after several months’ storage, were found to be contaminated with aflatoxin B1.

Antimicrobial activity and Characterization of Marine bacteria.

Marine bacteria were isolated from seawater was collected from different coastal areas of the Tamilnadu Sea. The antimicrobial activities of these bacteria were investigated. Ethyl acetate extracts of marine bacterial fermentation were screened for antimicrobial activities using the method of agar diffusion. The results showed that 25 strains of the isolates have antimicrobial activity. The proportion of active bacteria associated with isolated from seawater. The active marine bacteria were assigned to the genera Alteromonas, Pseudomonas, Bacillus and Marinobacter. The TLC autobiographic overlay assay implied that the antimicrobial metabolites produced by four strains with wide antimicrobial spectrum were different. These marine bacteria were expected to be potential resources of natural antibiotic products. It can be concluded that isolation of Marine bacterial samples can offer a numbers of microbial strains for sources of new biomolecules from Marine sources.

Differential modification of radiation damage in 5-bromo-2-deoxy-uridine sensitized human glioma cells and PHA-stimulated peripheral leukocytes by 2-deoxy-D-glucose.

Effects of 5-bromo-2-deoxy-uridine (BrdU) and 2-deoxy-D-glucose (2-DG) on 60-Co-gamma-ray induced damage were studied in monolayer cultures of glioma (BMG-1) cells, and PHA-stimulated peripheral leukocytes from normal donors. Micronuclei formation was used as an index of cytogenetic damage. BrdU and 2-DG treatments did not induce micronuclei formation in unirradiated cultures. Presence of BrdU (0.8 microM) for more than one cell cycle (24 hr) significantly increased gamma-ray (1-4 Gy) induced micronuclei formation in exponentially growing BMG-1 cells. Incubation of irradiated cells under sub-optimal growth conditions (DMEM with 1% serum) for 3 hr, instead of growth medium, significantly decreased micronuclei formation. Post-irradiation presence of 2-DG (5 mM; 3 hr, in DMEM + 1% serum) significantly increased radiation damage. In BrdU sensitized cells also, 2-DG significantly increased radiation damage further. In PHA-stimulated leukocytes from normal donors, 2-DG (5mM, equimolar with glucose; for 2 hr) did not increase gamma-ray (2-Gy, 42 hr after PHA-stimulation) induced micronuclei formation. Pre-irradiation presence of BrdU (1.6 microM) significantly increased micronuclei. On the contrary, 2-DG treatment reduced radiation induced micronuclei formation in BrdU sensitized leukocyte cultures. These results suggest that (i) radiation induced lesions leading to micronuclei formation in proliferating tumour cells, are, at least, partly repairable; (ii) combination of 2-DG could reduce BrdU doses required for radiosensitization of proliferating tumour cells; and (iii) 2-DG could differentially increase radiation damage in BrdU sensitized proliferating tumour cells, while reducing manifestation of damage in normal proliferating cells.