Kiran Nehra

Biodiversity of phosphate solubilizing bacteria in rhizosphere of chickpea, mustard and wheat grown in different regions of Haryana.

The native population of phosphate solubilizing bacteria (PSB) was studied in the rhizosphere of chickpea, mustard and wheat grown in different regions of Haryana. A total of 193 PSB were isolated from 245 rhizospheric samples collected from south-west and north-east zones. The PSB count showed large variations (3−67 × 105cfu/g) and biodiversity within the crop and place of sampling. Using biochemical analysis, the isolates were tentatively identified as belonging to four genera, Pseudomonas, Aeromonas, Klebsiella and Enterobacter. Phosphate solubilization of these isolates varied from 5.9 to 123.8% and 2.2 to 227.2 μg/ml in solid and liquid Pikovskaya’s medium, respectively. Based on their morphological traits, all the isolates were placed into 20 groups, majority of them falling in the group having white, round and gummy colonies, irrespective of the crop or the region. The intrinsic antibiotic resistance pattern showed large variations among the isolates and most of the isolates were resistant to streptomycin, ampicillin and penicillin. The highest PSB number and greatest variability were found in the rhizosphere of chickpea, followed by wheat and then mustard.

Effect of Additives on the Activity of Tannase from Aspergillus awamori MTCC9299

Tannase from Aspergillus awamori MTCC 9299 was purified using ammonium sulfate precipitation followed by ion-exchange chromatography. A purification fold of 19.5 with 13.5% yield was obtained. Temperature of 30 °C and pH of 5.5 were found optimum for tannase activity. The effects of metals and organic solvents on the activity of tannase were also studied. Metal ions Mg+2, Mn+2, Ca+2, Na+, and K+ stimulated the tannase activity, while Cu+2, Fe+3, and Co+2 acted as inhibitors of the enzyme. The addition of organic solvents like acetic acid, isoamylalcohol, chloroform, isopropyl alcohol, and ethanol completely inhibited the enzyme activity. However, butanol and benzene increased the enzyme activity.

Characterization of heat resistant mutant strains of Rhizobium sp. [Cajanus] for growth, survival and symbiotic properties.

Fourteen heat resistant mutant strains were isolated from a wild-type strain (PP201, Nod+ Fix+) of Rhizobium sp. (Cajanus) by giving it a heat shock of 43°C. These mutant strains showed a greater increase in optical density (O.D.) and a higher viable cell count in both rhizospheric and non-rhizospheric soil at high temperature. Symbiotic studies showed that pigeon pea plants inoculated with a few mutant strains had ineffective nodules (Nod+ Fix−) under controlled temperature (43°C) conditions, but under natural high temperature (40–45°C) conditions, the host plants infected with all the mutant strains showed higher total shoot nitrogen than the plants inoculated with the parent strain. Four mutant strains (HR-3, HR-6, HR-10 and HR-12) were found to be highly efficient for all the symbiotic parameters, and thus have the potential to be used as bioinoculants in the North-Western regions of India during the summer season.

Bacteriocins from Lactic Acid Bacteria

Probiotics are the beneficial bacteria that are indigenous to a healthy digestive system. Basically, these are live microorganisms, which are administered in adequate amounts in order to provide health benefit to the host. They work by crowding out the bad bacteria within the digestive system and then attaching themselves to the intestinal wall where they increase the number of beneficial bacteria regulating and maintaining balance between the beneficial and harmful bacteria. The tradition of eating foods (such as yogurt, sauerkraut, fermented milk, miso and soy beverages) fermented with bacteria is solely based on health benefits provided by these bacteria. Thousands of different lactic acid bacteria (LAB) are used as probiotics, and the dominant members are Bifidobacteria (Bifidobacterium bifidum) and Lactobacteria (Lactobacillus acidophilus, Lactobacillus plantarum). The benefits associated with the use of probiotic bacteria are well documented, but their mechanism of action still remains very unclear. LAB protect food from spoilage and pathogenic microorganisms by producing organic acids, hydrogen peroxide, diacetyl, antifungal compounds such as fatty acids or phenyllactic acid and bacteriocins. Bacteriocins are a heterogeneous family of small, heat-stable peptides that are produced by many bacterial species, including many probiotic strains. Bacteriocins of LAB are considered as safe natural preservatives with potent antimicrobial activities and antagonistic affect. Bacteriocins mainly prevent food spoilage by inhibiting growth of food-borne pathogenic microorganisms. They also protect the body from cancer and effectively improve the immune system. These are classified into several groups in which classes I (Lantibiotics) and II (Bacteriocins) are studied most thoroughly. The present review is concerned with the diversity of bacteriocins, their expression system and their applications which lead to use of lactic acid bacteria as probiotics.

Molecular Basis of Salt Tolerance in Wheat and Other Crop Plants

Among abiotic stresses, salinity has become a major problem adversely affecting the growth of crop plants grown under saline conditions. In India, an area of about 5.5 mha is already under salinity and 3.6 mha under sodicity problem, and still larger area is coming under potential salinity problem due to injudicious use of water under canal irrigation system. The plant growth in saline conditions is inhibited mainly by the toxic effect of increased sodium accumulation and nonavailability of water. Thus, salt stress is a major agricultural issue that demands an immediate attention. Various mechanisms to avoid salt accumulation inside cells of root and leaf include sodium exclusion, its sequestration in vacuoles, production of compatible solute, and acceleration of reactive oxygen species scavenging systems. Understanding these mechanisms at physiological and molecular levels is needed to identify new genetic sources of salt tolerance and improve the selection process in breeding. More recently, in addition to the conventional mechanisms, several genomic approaches are being used in improving salt tolerance in plants. A significant progress has been made on identification of genes for salt tolerance in wheat, and the studies related to gene expression are underway. This review describes the various tolerance mechanisms adopted by crop plants, especially wheat, under saline conditions.

ICT : A new horizon in Indian agriculture

Recent developments in information and communication technology (ICT) offer exciting new opportunities for rapid and efficient information transfer including trans-border data flow through electronic systems such as Internet. The versatile application of ICT in diverse fields including agriculture is in fact an outcome of its special capabilities in terms of speed, accuracy, consistency and storage capability. In todays fast changing scenario, the Indian agriculturist cannot afford to ignore the use of ICT for transfer of information. The present paper reviews the issues associated with integration of ICT and agriculture as well as the novel developments that are evolving in agricultural information dissemination. In addition, some rapidly emerging technologies involved in improving agricultural economy such as remote sensing and digital agriculture are also discussed.