<i>Lac</i>Z<i> </i>Tagging of Phosphate Solubilizing <i>Pseudomonas striata </i>for Rhizosphere Colonization

275-279The Tn5-lacZ marker was used for detection of phosphobacteria, Pseudomonas striata (P-27) in the soybean rhizosphere. The chromogenic marker lacZ (structural gene for β-galactosidase) was introduced into P. striata (P-27) by transposition of Tn5-lacZ from Escherichia coli (S17-1). The mutants, which expressed β-galactosidase activity on selective media seeded with X-gal and IPTG, were screened for P-solubilization and IAA production. Mutant strains (lacZ marked) designated as superior, inferior and isogenic to wild type (P-27) with respect to P-solubilization (T-80, T-125, T-125) and IAA production (T-49, T-57, T-57) were inoculated to soybean in a pot experiment. The inoculated strains were recovered from the rhizosphere at different periods of plant growth by plating on selective medium using lac+ phenotype. A comparison between various mutants in terms of their abilities to colonize the soybean rhizosphere revealed that lacZ insertion or mutational over-expression of plant growth promoting traits did affect the establishment, population dynamics and ecological fitness of phosphobacteria. The technique of monitoring the tagged strains by direct plating on selective medium was found to be superior compared to conventional techniques

Efficacy of a Rock Phosphate Based Soil Implant Formulation of Phosphobacteria in Soybean <i>(Glycine max </i>Merrill)

180-187For improving the effectiveness of low-grade rock phosphate, a granular formulation was developed by immobilizing phosphate solubilizing bacteria (PSB) impregnated rock phosphate in calcium alginate. This process ensured requisite standards of PSB viability in rock phosphate. The formulation was compared with powdered soil and seed formulations for its efficacy in soybean; maximum weight of nodule, dry matter and grain yield, N and P uptake of shoot and grain were recorded with granular preparation. The granular formulation can directly be applied in soil and is environmentally safe

Use of Heavy Metals for Quantification of Rhizobia and Suppression of Bacterial Contaminants in Carrier Based Inoculants

577-582Quality analysis of commercial legume inoculants involves determination of number of live rhizobia of appropriate species per unit weight of carrier. Conventional analysis is performed by means of plate counts of rhizobia on CRYEMA, but contaminants sometimes suppress/mask the growth of rhizobial colonies and make their counts unrealistic. Plant infection-most probable number (MPN) assay is considered to be more reliable, but is relatively expensive and time consuming. In the present study, a selective medium is devised, which permits growth of selected strains of rhizobia and at the same time refrains the growth of contaminants on plates. To inhibit nonrhizobial contaminants in carrier based inoculants, heavy metals were added in different combinations. A combination of Zn and Co at a concentration of 50 ppm each was found to inhibit bacterial contaminants without impeding the growth of rhizobial colonies on CRYEMA. However, these additions were not effective in refraining the proliferation of contaminants in charcoal-soil based rhizobial inoculants at this concentration. These metals when used in higher concentrations in charcoal-soil based inoculants, adversely affected nodulation and the dry matter yield of soybean

Age-diagnostic dinoflagellate cysts from the lignite-bearing sediments of the Vastan lignite mine, Surat district, Gujarat, western India

The lignite-bearing succession (corresponding to Cambay Shale) of the Vastan lignite mine, Gujarat has been extensively studied in the past few years for its rich vertebrate fauna. However, no age-diagnostic fossils with chronological significance are reported. In the present study, several dinoflagellate cysts from different levels in the lignite-bearing sediments (Succession A) of the Vastan lignite mine arc identified which are age diagnostic. Occurrence of Muratodinium Jimbriatum, Heteraulacacysta granulata and Operculodinium severind in the lower part indicates an age not older than late Thanetian/Sparnacian (-55 Ma). Presence of rich Kenleyia complex including LAD of Kenleyiu lophophora in the upper half of the succession indicates basal Ypresian age (-54 Ma). Occurrence of Lanternosphaeridium lanosum in the upper part suggests an age not younger than middle Ypresian (-52 Ma) for the topmost part of the Vastan succession. Thus, in terms of traditional European stages, the succession ranges from Ilerdian to basal Cuisian (-55-52 Ma) corresponding to upper SBZ7 to basal SBZI 0 larger foraminifera zones. Age of the mammal fossil horizons in the lower part of the succession appears to be Sparnacian (-55-54 Ma)

Paleogene larger foraminifera: reference List

An annotated list of publications regarding larger foraminifera of Paleogene age has been compiled from different sources. This list will help the students of Paleogene larger foraminifera to retrieve the literature regarding different taxa