Biomedical subjects

C S Nautiyal

Publications and source records attributed to C S Nautiyal.

13 recordsLinked to original sources

PubMed2006

Biologic control ability of plant growth-promoting Paenibacillus lentimorbus NRRL B-30488 isolated from milk.

A plant growth-promoting Paenibacillus lentimorbus NRRL B-30488 (B-30488) was isolated from cows' milk. Bacterial colonization and growth responses of different plant species after inoculation with B-30488 were evaluated in a controlled environment and in microplot assays. Survival and colonization of B-30488 in the phytosphere of plants and soil was monitored using a chromosomally located rifampicin-marked mutant B-30488 (B-30488R). The strain showed variable ability to invade plants. The interaction between B-30488R and Fusarium oxysporum f. sp. ciceri was studied by scanning electron microscopy. Chitinase and beta-1,3-glucanase enzymes were produced when B-30488R was grown in the presence of colloidal chitin as sole carbon source. Deliberate dilution of B-30488R with field soil offers a reliable process for decreasing the cost of bacterial inoculants in developing countries. Seed treatment of chickpea demonstrated significantly (P = 0.05) greater seedling mortality in nonbacterized compared with bacterized seedlings. Bacterization significantly (P = 0.05) improved seed germination, plant height, number of pods/plant(-1), and seed dry weight.

Animals↗

PubMed2001

An efficient method for qualitative screening of phosphate-solubilizing bacteria.

An efficient protocol was developed for qualitative screening of phosphate-solubilizing bacteria, based upon visual observation. Our results indicate that, by using our formulation containing bromophenol blue, it is possible to quickly screen on a qualitative basis the phosphate-solubilizing bacteria. Qualitative analysis of the phosphate solubilized by various groups correlated well with grouping based upon quantitative analysis of bacteria isolated from soil, effect of carbon, nitrogen, salts, and phosphate solubilization-defective transposon mutants. However, unlike quantitative analysis methods that involve time-consuming biochemical procedures, the time for screening phosphate-solubilizing bacteria is significantly reduced by using our simple protocol. Therefore, it is envisaged that usage of this formulation based upon qualitative analysis will be salutary for the quick screening of phosphate-solubilizing bacteria. Our results indicate that the formulation can also be used as a quality control test for expeditiously screening the commercial bioinoculant preparations, based on phosphate solubilizers.

Bacteria↗

PubMed2000

Stress induced phosphate solubilization in bacteria isolated from alkaline soils.

Phosphate solubilizing bacteria NBRI0603, NBRI2601, NBRI3246 and NBRI4003 were isolated from the rhizosphere of chickpea and alkaline soils. All four strains demonstrated diverse levels of phosphate solubilization activity under in vitro conditions in the presence of various carbon and nitrogen sources. Acid production may have contributed to phosphate solubilization, but was not the only reason for phosphate release into the medium. Among the four strains, NBRI2601 was the most efficient strain in terms of its capability to solubilize phosphorus in the presence of 10% salt, pH 12, or 45 degrees C. The strains showed varied levels of phosphate solubilization when the effects of different sources of nitrogen were examined during growth. The presence of low levels of Ca(2+) and EDTA in the medium enhanced phosphate solubilization.

Bacteria↗

PubMed2000

Crossing the limits of Rhizobium existence in extreme conditions.

An ecological survey was conducted to characterize 5000 Rhizobium sp. sesbania strains of diverse geographical origin, isolated from the root nodules of Sesbania aculeata growing in neutral (pH 7) and alkaline (pH 8.5 and above) soils. The rhizobia from the alkaline soil showed significantly higher salt tolerance than those isolated from neutral soil. Upper limits of stress survival of rhizobial isolates, Rhizobium sp. NBRI0102 sesbania selected from neutral soil, and Rhizobium sp. NBRI2505 sesbania selected from alkaline soil, were studied under free living conditions. Rhizobium sp. NBRI0102 sesbania and Rhizobium sp. NBRI2505 sesbania tolerated yeast extract mannitol broth (YEB) containing 10% and 28% salt (NaCl, wt/vol) for up to 18 h of incubation at 30 degrees C. Growth of Rhizobium sp. NBRI0102 sesbania and Rhizobium sp. NBRI2505 sesbania at pH 7, 11, and 12 was identical, except for a lag period of about 10 h in the growth of Rhizobium sp. NBRI0102 sesbania at pH 11 and 12, as compared with pH 7. Rhizobium sp. NBRI0102 sesbania and Rhizobium sp. NBRI2505 sesbania survived at 50 degrees C and 65 degrees C, in YEB at pH 7 for up to 4 and 2 h, respectively. To our knowledge, this is the first report of rhizobia demonstrating survival of Rhizobium sp. NBRI2505 sesbania, estimated by counting viable cells, to such extreme conditions of salt and temperature, individually. In contrast to Rhizobium sp. NBRI0102 sesbania, high temperature was tolerated efficiently by Rhizobium sp. NBRI2505 sesbania, in the presence of salt at higher pH. Our results suggest that the possession of the trait of high salt tolerance might be of some evolutionary significance for the survival of rhizobia in alkaline soils, at high pH and temperature.

Fabaceae↗

PubMed2000

Effects of salt and pH stress on temperature-tolerant Rhizobium sp. NBRI330 nodulating Prosopis juliflora.

A study was conducted to examine the growth response of a rhizobial strain Rhizobium sp. NBRI330 isolated from root nodules of Prosopis juliflora growing in alkaline soil. The strain had the ability to nodulate P. juliflora. Nursery grown plants inoculated with Rhizobium sp. NBRI330 had 60.6% higher plant dry weight, as compared with uninoculated plants. The individual stress survival limit of a rhizobial strain Rhizobium sp. NBRI330 isolated from alkaline soil in a medium containing 32% (wt/vol) salt was 8 h, and at 55 degrees C up to 3 h. The length of Rhizobium sp. NBRI330 in salt-stressed cells increased significantly to 3.04 microm from 1.75 microm of non-stressed control cells. On the contrary, the length of pH-stressed cells declined to 1.40 microm. Compared with non-stressed control rod-shaped cells, the shape of temperature-stressed cells changed to spherical, of 0.42 microm diameter. High temperature (45 degrees C) was tolerated efficiently by Rhizobium sp. NBRI330 in the presence of salt at pH 12, as compared with pH 7.

Colony Count, Microbial↗

PubMed1999

An efficient microbiological growth medium for screening phosphate solubilizing microorganisms.

A novel defined microbiological growth medium, National Botanical Research Institute's phosphate growth medium (NBRIP), which is more efficient than Pikovskaya medium (PVK), was developed for screening phosphate solubilizing microorganisms. In plate assay the efficiency of NBRIP was comparable to PVK; however, in broth assay NBRIP consistently demonstrated about 3-fold higher efficiency compared to PVK. The results indicated that the criterion for isolation of phosphate solubilizers based on the formation of visible halo/zone on agar plates is not a reliable technique, as many isolates which did not show any clear zone on agar plates solubilized insoluble inorganic phosphates in liquid medium. It may be concluded that soil microbes should be screened in NBRIP broth assay for the identification of the most efficient phosphate solubilizers.

Bacillus↗

PubMed1992

Diauxic growth of Agrobacterium tumefaciens 15955 on succinate and mannopine.

Diauxic growth was observed upon incubation of Agrobacterium tumefaciens 15955 on a mixture of succinate and mannopine as the carbon source. Diauxic growth was also observed when either fumarate or L-malate was mixed with mannopine. No diauxie was detectable when A. tumefaciens 15955 was grown on a mixture of mannopine and glucose, fructose, sucrose, or L-arabinose. Preferential utilization of succinate was observed in the initial growth phase of diauxie, whereas the final growth phase occurred at the expense of mannopine. Cells harvested during the initial growth phase exhibited a capacity for uptake of [14C]succinate but not of [14C] mannopine. A capacity for [14C]mannopine uptake was expressed during the final growth phase. Extracts from cells grown on a mixture of succinate and mannopine exhibited a low level of mannopine cyclase activity in the initial phase of diauxie. This activity increased substantially in the final phase of growth. Added succinate had no effect on the rate of [14C]mannopine uptake or mannopine cyclase activities of cells previously grown on mannopine. Diauxie was also observed during growth of strain 15955 on a mixture of succinate and octopine.

Agrobacterium tumefaciens↗

PubMed1992

Spontaneous mutation conferring the ability to catabolize mannopine in Agrobacterium tumefaciens.

Two nopaline-type strains of Agrobacterium tumefaciens, C58 and T37, as well as strain A136, which is a Ti plasmid-cured derivative of strain C58, gave rise to spontaneous mutants that were able to grow on mannopine. The observation of mutagenesis with strain A136 demonstrated that the ability to acquire this new catabolic potential was independent of the presence of a Ti plasmid. The mutants were isolated after 4 weeks of incubation on minimal medium containing mannopine as the sole carbon source. They also utilized mannopinic acid, but not agropine or agropinic acid. In addition, the spontaneous mutant LM136, but not its parent strain A136, degraded many mannityl opine analogs. [14C]mannopine disappeared in the presence of LM136 cells which had been pregrown on opine or nonopine substrates. These results suggested that the catabolic system of this mutant was not subject to a stringent regulation. A clone conferring the ability to utilize mannopine on a recipient pseudomonad was selected from a genomic library from both the mutant LM136 and its parent strain. Only the LM136 clone was expressed in the parent Agrobacterium strain A136. Southern analysis showed that the genes for mannopine catabolism in the spontaneous mutants differed from the corresponding Ti plasmid-encoded genes of octopine-type or agropine-type Agrobacterium strains. Cells of LM136 utilized [14C]mannopine without generating detectable amounts of intracellular agropine. In contrast, a major fraction of the radioactivity recovered from cells of the octopine-type strain Ach5, after incubation on [14C]mannopine, was in the form of agropine.

Agrobacterium tumefaciens↗

PubMed1991

Mannopine and mannopinic acid as substrates for Arthrobacter sp. strain MBA209 and Pseudomonas putida NA513.

The characteristics of mannopine and mannopinic acid utilization by Agrobacterium tumefaciens B6S3, Arthrobacter sp. strain MBA209, and Pseudomonas putida NA513 were studied. Strain B6S3 utilized the four mannityl opines, mannopine, mannopinic acid, agropine, and agropinic acid. It also utilized several mannityl opine analogs, which were modified in either the sugar or the amino acid moiety. It utilized mannopine more rapidly after preincubation on mannopine, mannopinic acid, or glutamine than after pregrowth on glucose, mannose, or mannitol. Strains MBA209 and NA513 utilized mannopine and mannopinic acid, but not the other two mannityl opines. They utilized few mannityl opine analogs, sometimes because of failure to utilize the products of initial cleavage of the analog. Utilization of mannopine and mannopinic acid by strain NA513 was strictly dependent on prior growth on these substrates. A spontaneous regulatory variant of strain NA513 remained unable to utilize most of the mannityl opine analogs. Glutamine, mannose, and several analogs had no inhibitory effect on [14C]mannopine utilization by strain NA513.

Arthrobacter↗

PubMed1990

Characterization of the Opine-Utilizing Microflora Associated with Samples of Soil and Plants.

Microorganisms utilizing an opine as the sole carbon source were recovered from crown gall tumors, soil, and surface-disinfected potato tubers. The effect of the opines octopine, nopaline, succinamopine, and mannopine as selective substrates was compared with that of the auxin indoleacetic acid. Selection on octopine and indoleacetic acid favored the fluorescent pseudomonads, whereas mannopine allowed the frequent recovery of agrobacteria. Coryneforms which utilized succinamopine or mannopine were detected in soil, but not in tumors. Fungi growing on succinamopine or mannopine and a mannopine-utilizing Pseudomonas putida were isolated from tumor and soil, respectively.

Journal Article↗

PubMed1989

Cytochrome mutants of bradyrhizobium induced by transposon tn5.

Transposon Tn5 was used to mutate Bradyrhizobium japonicum USDA 61N. From over 5000 clones containing Tn5, 12 were selected and purified using a chemical reaction to identify oxidase-deficient clones. Four classes of mutants were identified based on the alterations in cytochromes. Most of the mutants had alterations in more than one cytochrome. Southern hybridization analysis of restricted genomic DNA of a representative strain of each class demonstrated that each mutant had a single Tn5 insert. Thus a single Tn5 insert produced pleiotropic effects on cytochromes. One class, which was totally deficient in cytochromes aa(3) and c, produced ineffective nodules on soybeans. Most of the strains representing the other classes produced effective nodules but exceptions were observed in each class. Bacteroids of the wild-type strain contained cytochrome aa(3). Bacteroids from one class of mutants were totally devoid of cytochrome aa(3). Several of these strains produced effective symbioses indicating that cytochrome aa(3) is not required for an effective symbiosis in this DNA homology group II strain which normally has this terminal oxidase in bacteroids.

Journal Article↗

PubMed1989

Characterization of a wide host range plasmid pANV-6 from Citrobacter diversus.

pANV-6 is a 5.85 kb, streptomycin resistant, high copy number plasmid isolated from a multi drug resistant clinical isolate of C. diversus by transformation in Escherichia coli C-600. The plasmid was very stable, noncurable and could not be amplified with chloramphenicol. It was non-conjugative among Enterobacteriaceae hosts. Plasmid was transferred by transformation to several Gram negative and Gram positive hosts. These included Esch. coli, Serratia marcescens, Salmonella typhimurium, Klebsiella pneumoniae, Staphylococcus aureus, Corynebacterium glutamicum. From Staph. aureus it was transferred by conjugation to other Staph. aureus, Staph. epidermidis and Bacillus subtilis. Plasmid was incompatible with standard plasmids belonging to incompatibility groups H1, H2 = S,J,P and T of coliform bacteria. Plasmid has one site for restriction enzyme EcoRI and Pst I, three for Bgl 1 and non for Bgl 1, Bam HI, Hind III and X ba I.

Citrobacter↗

PubMed1988

Nodulation, Nitrogen Fixation, and Hydrogen Oxidation by Pigeon Pea Bradyrhizobium spp. in Symbiotic Association with Pigeon Pea, Cowpea, and Soybean.

The pigeon pea strains of Bradyrhizobium CC-1, CC-8, UASGR(S), and F4 were evaluated for nodulation, effectiveness for N(2) fixation, and H(2) oxidation with homologous and nonhomologous host plants. Strain CC-1 nodulated Macroptilium atropurpureum, Vigna unguiculata, Glycine max, and G. soja but did not nodulate Pisum sativum, Phaseolus vulgaris, Trigonella foenum-graecum, and Trifolium repens. Strain F4 nodulated G. max cv. Peking and PI 434937 (Malayan), but the symbioses formed were poor. Similarly, G. max cv. Peking, cv. Bragg, PI 434937, PR 13-28-2-8-7, and HM-1 were nodulated by strain CC-1, and symbioses were also poor. G. max cv. Williams and cv. Clark were not nodulated. H(2) uptake activity was expressed with pigeon pea and cowpea, but not with soybean. G. max cv. Bragg grown in Bangalore, India, in local soil not previously exposed to Bradyrhizobium japonicum formed nodules with indigenous Bradyrhizobium spp. Six randomly chosen isolates, each originating from a different nodule, formed effective symbioses with pigeon pea host ICPL-407, nodulated PR 13-28-2-8-7 soybean forming moderately effective symbioses, and did not nodulate Williams soybean. These results indicate the six isolates to be pigeon pea strains although they originated from soybean nodules. Host-determined nodulation of soybean by pigeon pea Bradyrhizobium spp. may depend upon the ancestral backgrounds of the cultivars. The poor symbioses formed by the pigeon pea strains with soybean indicate that this crop should be inoculated with B. japonicum for its cultivation in soils containing only pigeon pea Bradyrhizobium spp.

Journal Article↗