Generation of Variability for Salt Tolerance in Rice Using Tissue Culture Techniques

The study deals with the generation of variability for salt tolerance in rice using tissue culture techniques. Rice is the staple food of more than half of the world’s population. The management of drought, salinity and acidity in soils are all energy intensive agricultural practices. The Genetic variability is the basis of crop improvement. Somaclonal and androclonal variation can be effectively used for this purpose. In the present study, eight isozymes were studied and esterase and isocitric dehydrogenase was found to have varietal specific, developmental stage specific and stress specific banding pattern in rice. Under salt stress thickness of bands and enzyme activity showed changes. Pokkali, a moderately salt tolerant variety, had a specific band 7, which was present only in this variety and showed slight changes under stress. This band was faint in tillering and flowering stage .Based on the results obtained in the present study it is suggested that esterase could possibly be used as an isozyme marker for salt tolerance in rice. Varietal differences and stage specific variations could be detected using esterase and isocitric dehydrogenase . Moreover somaclonal and androclonal variation could be effectively detected using isozyme markers.

Proline Accumulation and Salt Tolerance in Rice

The morphological and biochemical response of calli and seedlings of different rice cultivars were compared under acid saline conditions. Calli of both tolerant and sensitive varieties showed severe stress symptoms like browning and necrosis, but the onset of stress symptoms was delayed in Pokkali. Seedlings of Pokkali showed minimal stress symptoms in lower salinities, and curling and senescence of older leaves in higher salinities although plants revived on amelioration of stress. Seedlings of the other varieties showed severe stress symptoms even at low salinities and plant death at higher salinities. Salt stress induced accumulation of the putative osmoprotectant proline in calli and seedlings of all varieties. Proline accumulation was higher in sensitive varieties than in Pokkali. These results indicate that proline accumulation is not directly correlated with salt tolerance in rice.

Characterization of laccase from Streptomyces psammoticus: an enzyme for eco-friendly treatment of environmental pollutants

The present study has identified an actinomycete culture (S. psammoticus) which was capable of producing all the three major ligninolytic enzymes. The study revealed that least explored mangrove regions are potential sources for the isolation of actinomycetes with novel characteristics. The laccase production by the strain in SmF and SSF was found to be much higher than the reported values. The growth of the organism was favoured by alkaline pH and salinity of the medium. The enzyme also exhibited novel characteristics such as activity and stability at alkaline pH and salt tolerance. These two characters are quite significant from the industrial point of view making the enzyme an ideal candidate for industrial applications. Many of the application studies to date are focused on enzymes from fungal sources. However, the fungal laccases, which are mostly acidic in nature, could not be used universally for all application purposes especially, for the treatment of effluents from different industries, largely due to the alkaline nature of the effluents. Under such situations the enzymes from organisms like S. psammoticus with wide pH range could play a better role than the fungal counterparts. In the present study, the ability of the isolated strain and laccase in the degradation of dyes and phenolic compounds was successfully proved. The reusability of the immobilized enzyme system made the entire treatment process inexpensive. Thus it can be concluded from the present study that the laccase from this organism could be hopefully employed for the eco-friendly treatment of dye or phenol containing industrial effluents from various sources.

Thermodynamics of transfer of polar nonelectrolytes from water to aqueous salt solutions

The Setschenow parameter and thermodynamic parameters of transfer of a number of monosubstituted benzoic acids from water to different salt solutions have been reported. The data have been rationalized by considering the structure breaking effects of the ions of the salts, the localised hydrolysis model, the internal pressure theory and Symons' theory of water structure.

Solubility of 4-Nitrobenzoic Acid in Water & Salt Solutions

Solubilities of 4-nitrobenzoic acid at 25°, 35° and 42°C have been determined in water and in the presence of several concentrations of electrolytes. The free energies, enthalpies and entropies of transfer are also reported. The data have been rationalized by considering the structure-breaking effects of the ions of the salts and the requirement of the localized hydrolysis model. The theory of Symons is not satisfactory to rationalise the experimental data.

Thermodynamic Parameters of Transfer of 2-Nitrobenzoic Acid & 3-Nitrobenzoic Acid from Water to Aqueous Salt Solutions

The Setschenow parameters of solubility in salt solutions and the thermodynamic parameters (25·C) of transfer from aqueous solution to aqueous salt solutions for 2-nitrobenzoic acid and 3-nitrobenzoic acid have been reported. The data have been rationalized on the basis of the localized hydrolysis model and the structure breaking action of ions of the electrolytes.

Thermodynamics of Transfer of Aminobenzoic Acids from Water to Aqueous Salt Solutions

The Setschenow parameter and thermodynamic parameters of transfer of 2- and 4-aminobenzoic acids from water to salt solutions have been reported. The results are discussed in terms of the structure- breaking effects of the ions of the salts, the localized hydrolysis model, and the internal pressure theory.

Paddy Field Cyanobacteria : Diversity and Pesticide Tolerance

School of Environmental Studies, Cochin University of Science and Technology

Studies on exopolysaccharide production by probiotic Lactic acid bacteria

The thesis mainly discussed the isolation and identification of a probiotic Lactobacillus plantarum, fermentative production of exopolysaccharide by the strain, its purification, structural characterisation and possible applications in food industry and therapeutics. The studies on the probiotic characterization explored the tolerance of the isolated LAB cultures to acid, bile, phenol, salt and mucin binding. These are some of the key factors that could satisfy the criteria for probiotic strains . The important factors required for a high EPS production in submerged fermentation was investigated with a collection of statistical and mathematical approach. Chapter 5 of the thesis explains the structural elucidation of EPS employing spectroscopic and chromatographic techniques. The studies helped in the exploration of the hetero-polysaccharide sequence from L. plantarum MTCC 9510. The thesis also explored the bioactivities of EPS from L. plantarum. As majority of chemical compounds identified as anti-cancerous are toxic to normal cells, the discovery and identification of new safe drugs has become an important goal of research in the biomedical sciences. The thesis has explored the anti-oxidant, anti-tumour and immunomodulating properties of EPS purified from Lactobacillus plantarum. The presence of (1, 3) linkages and its molecular weight presented the EPS with anti-oxidant, anti-tumour and immunomodulating properties under in vitro conditions.

Increased prevalence of indicator and pathogenic bacteria in Vembanadu Lake: a function of salt water regulator, along south west coast of India

Prevalence of faecal indicator bacteria, Escherichia coli and pathogenic bacteria, Vibrio cholerae, Vibrio parahaemolyticus and Salmonella were analysed in Vembanadu lake (98350N 768250E), along south west coast of India for a period of one year from ten stations on the southern and northern sides of a salt water regulator constructed in Vembanadu Lake in order to prevent incursion of seawater during certain periods of the year. While the northern side of the lake has a connection to the sea, the southern side is enclosed when the salt water regulator is closed. The results revealed the water body is polluted with high faecal coliform bacteria with mean MPN value ranging from 1718-7706/100 ml. E. coli, V. cholerae, V. parahaemolyticus and Salmonella serotypes such as S. paratyphi A, B, C and S. newport were isolated and this is the first report on the isolation of these Salmonella serovars from this lake. E. coli showed highest percentage of incidence (85.6–86.7%) followed by Salmonella (42–57%), V. choleare (40–45%) and V. parahaemolyticus (31.5–32%). The increased prevalence of indicator and pathogenic bacteria in the enclosed southern part of Vembanadu Lake may be resulting from the altered flow patterns due to the salt water regulator.

Influence of a Salt Water Regulator on the Survival Response of Salmonella Paratyphi in Vembanadu Lake: India

Contamination of environmental water by pathogenic microorganisms and subsequent infections originated from such sources during different contact and non- contact recreational activities are a major public health problem worldwide particularly in developing countries. The main pathogen frequently associated with enteric infection in developing countries are Salmonella enterica serovar typhi and paratyphi. Although the natural habitat of Salmonella is the gastrointestinal tract of animals, it find its way into natural water through faecal contamination and are frequently identified from various aquatic environments (Baudart et al., 2000; Dionisio et al., 2000; Martinez -Urtaza et al., 2004., Abhirosh et al., 2008). Typhoid fever caused by S. enterica serotype typhi and paratyphi are a common infectious disease occurring in all the parts of the world with its highest endemicity in certain parts of Asia, Africa, Latin America and in the Indian subcontinent with an estimated incidence of 33 million cases each year with significant morbidity and mortality (Threlfall, 2002). In most cases the disease is transmitted by polluted water (Girard et al., 2006) because of the poor hygienic conditions, inadequate clean water supplies and sewage treatment facilities. However in developed countries the disease is mainly associated with food (Bell et al., 2002) especially shellfish (Heinitz et al., 2000

Gut Associated Lactic Acid Bacteria Isolated from the Estuarine Fish Mugil cephalus: Molecular Diversity and Antibacterial Activities against Pathogens

In the present study we address the issue on gut associated lactic acid bacteria (LAB) isolated from the intestine of estuarine fish Mugil cephalus using de Man Rogossa and Sharpe (MRS) agar. LAB isolates were identified biochemically and screened for their ability to inhibit in vitro growth of various fish, shrimp and human pathogens. Most of the LAB isolates displayed an improved antagonism against fish pathogens compared to shrimp and human pathogens. Selected representative strains displaying high antibacterial activity were identified using 16S rRNA gene sequence analysis. Of the selected strains Lactobacillus brevis was the most predominant. Four other species of Lactobacillus, Enterobacter hormaechei and Enterobacter ludwigii were also identified. It was also observed that even among same species, considerable diversity with respect to substrate utilization persisted. Considering the euryhaline nature of grey mullet (Mugil cephalus), the LAB isolated from the gut possessed good tolerance to varying salt concentrations. This finding merits further investigation to evaluate whether the isolated LAB could be used as probiotics in various fresh and sea water aquaculture