Bio-preservation is a technique of extending the shelf life of food by using natural or controlled microbiota or antimicrobials. The fermentation products as well as beneficial bacteria are generally selected in this process to control spoilage and render pathogen inactive. The special interest organism or central organism used for this purpose is lactic acid bacteria (LAB) and their metabolites. They are capable to exhibit antimicrobial properties and helpful in imparting unique flavour and texture to the food products. The major compounds produced by LAB are bacteriocin, organic acids and hydrogen peroxide. Bacteriocin is peptides or proteins with antimicrobial activity. On the basis of size, structure and post-translational modification, bacteriocin is divided into four different classes. Due to non-toxic, non-immunogenic, thermo-resistance characteristics and broad bactericidal activity, LAB bacteriocins are considered good bio-preservative agents. The most common LAB bactriocin is nisin which has wider applications in food industry and has been Food and Drug Administration (FDA) approved. Nisin and other bacteriocin are being used in vegetables products, dairy and meat industries. Apart from LAB metabolites, bacteriophages and endolysins has promising role in food processing, preservation and safety. Bacteriocins and endolysins are more suitable for DNA shuffling and protein engineering to generate highly potent variants with expanded activity spectrum. Genetically modified bacteriophages may also be helpful in bio-preservation, however; their safety issues must be addressed properly before selection as bio-preservative agent.

A study was conducted using ten genetically diverse genotypes along with their 45F 1 (generated by diallel mating) under normal and salt stress conditions. Although, tomato (Lycopersicon esculentum Mill.) is moderately sensitive to salinity but more attention to salinity is yet to be required in the production of tomato. In present study, germination rate, speed of germination, dry weight ratio and Na + /K + ratio in root and shoot, were the parameters assayed on three salinity levels; control, 1.0 % NaCl and 3.0 % NaCl with Hoagland's solution. Increasing salt stress negatively affected growth and development of tomato. When salt concentration increased, germination of tomato seed was reduced and the time needed to complete germination lengthened, root/shoot dry weight ratio was higher and Na + content increased but K + content decreased. Among the varieties, Sel-7 followed by Arka Vikas and crosses involving them as a parent were found to be the more tolerant genotypes in the present study on the basis of studied parameters.

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The understanding of physio-biochemical and molecular attributes along with morphological traits contributing to the salinity tolerance is important for developing salt-tolerant rice (Oryza sativa L.) varieties. To explore these facts, rice genotypes CSR10 and MI48 with contrasting salt tolerance were characterized under salt stress (control, 75 and 150 mM NaCl) conditions. CSR10 expressed higher rate of physio-biochemical parameters, maintained lower Na/K ratio in shoots, and restricted Na translocation from roots to shoots than MI48. The higher expression of genes related to the osmotic module (DREB2A and LEA3) and ionic module (HKT2;1 and SOS1) in roots of CSR10 suppresses the stress, enhances electrolyte leakage, promotes the higher compatible solute accumulation, and maintains cellular ionic homeostasis leading to better salt stress tolerance than MI48. This study further adds on the importance of these genes in salt tolerance by comparing their behaviour in contrasting rice genotypes and utilizing specific marker to identify salinity-tolerant accessions/donors among germplasm; overexpression of these genes which accelerate the selection procedure precisely has been shown.

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