G. Archana - Academia.edu (original) (raw)

Papers by G. Archana

International Journal of Soil Science, 2011

Plant and Soil, 2016

Background and aimsHerbaspirillum seropedicae (Hs) Z67 a diazotrophic endophyte was genetically e... more Background and aimsHerbaspirillum seropedicae (Hs) Z67 a diazotrophic endophyte was genetically engineered for secretion of 2-keto-D-gluconic acid by heterologous expression of genes for pqq synthesis and gluconate dehydrogenase to study its beneficial effect on plants.MethodsTwo plasmids, pJNK5, containing a 5.1 Kb pqq gene cluster of Acinetobacter calcoaceticus and pJNK6, carrying in addition the Pseudomonas putida KT2440 gluconate dehydrogenase (gad) operon were constructed in pUCPM18Gmr under Plac promoter. H. seropedicae Z67 transformants were monitored for P and K solubilization, cadmium (Cd) tolerance and rice growth promotion.ResultsHs (pJNK5) secreted 23.5 mM gluconic acid and Hs (pJNK6) secreted 3.79 mM gluconic acid and 15.8 mM 2-ketogluconic acid respectively. Under aerobic conditions, Hs (pJNK5) and Hs (pJNK6) solubilized 239.7 μM and 457.7 μM P on HEPES rock phosphate and, 76.7 μM and 222.7 μM K on HRPF (feldspar), respectively, in minimal medium containing 50 mM glucose. Under N free minimal medium, similar effects of P and K solubilization were obtained. Hs (pJNK5) and Hs (pJNK6) inoculation increased the biomass, N, P, K content of rice plants (Gujarat – 17). These plants also accumulated 0.73 ng/g PQQ, and had improved growth and tolerance to CdCl2.ConclusionsIncorporation of pqq and gad gene clusters in H. seropedicae Z67 imparted additional plant growth promoting traits of P and K solubilization and ability to alleviate Cd toxicity to the host plant.

Journal of Basic Microbiology, 2015

Pollution of agricultural soils by Cu is of concern as it could bring about alterations in microb... more Pollution of agricultural soils by Cu is of concern as it could bring about alterations in microbial communities, ultimately eliminating certain plant beneficial bacteria thus disturbing soil fertility and plant growth. To understand the response of rhizobacterial communities upon Cu perturbation, mung bean (Vigna radiata) plants were grown in agricultural soil amended with CuSO4 (0-1000 mg kg(-1) ) under laboratory conditions. Culture-independent and -dependent Denaturing Gradient Gel Electrophoresis (CI-DGGE and CD-DGGE) fingerprinting techniques were employed to monitor rhizobacterial community shifts upon Cu amendment. In group specific PCR-DGGE, a negative impact was seen on α-Proteobacteria followed by β-Proteobacteria resulting in a concomitant decrease in diversity indices with increased Cu concentration. No significant changes were observed in Firmicutes and Actinomycetes populations. In CD-DGGE rhizobacterial community shift was observed above 500 mg kg(-1) (CuSO4 ), however certain bands were predominantly present in all treatments. Plants showed toxic effects by reduction in growth and elevated Cu accumulation, with root system being affected prominently. From this study it is evident that above 250 mg kg(-1) , rhizobacterial communities are adversely affected. α-Proteobacteria was found to be a sensitive bio-indicator for Cu toxicity and is of particular significance since this group includes majority of plant growth promoting rhizobacteria.

35 T. Satyanarayana et al. (eds.), Microorganisms in Sustainable Agriculture and Biotechnology, D... more 35 T. Satyanarayana et al. (eds.), Microorganisms in Sustainable Agriculture and Biotechnology, DOI 10.1007/978-94-007-2214-9_3, © Springer Science+Business Media BV 2012 ... by Rhizobacteria in Plant Growth Promotion G. Archana , A. Buch , and G. Naresh Kumar Page 2. ...

Indian journal of experimental biology, 2000

Carbamoyl phosphate synthetase (CPS) activity in Streptomyces lividans was repressed (70%) by add... more Carbamoyl phosphate synthetase (CPS) activity in Streptomyces lividans was repressed (70%) by addition of arginine and uracil in the growth medium. Enzyme activity was also inhibited by UMP and activated by ornithine and IMP. Pattern of inhibition and activation was similar irrespective of whether the cells were grown in medium supplemented with arginine or with uracil. A mutant of S. coelicolor with dual auxotrophy for arginine and uracil possessed only about 20% of CPS activity compared to the wild-type strain. An activity staining protocol has been developed for CPS enzyme. Using this method a single CPS band has been observed in the crude extracts of Escherichia coli as well as in S. lividans. Taken together, our results supported the conclusion that Streptomyces species might possess a single CPS enzyme unlike other gram-positive bacteria, which show the presence of two pathway-specific isozymes (Bacillus) or none (Lactobacillus and Leuconostoc).

International Biodeterioration & Biodegradation

Ecotoxicology and Environmental Safety, 2017

World journal of microbiology & biotechnology, 2016

Enterobacter asburiae PSI3 solubilizes mineral phosphates in the presence of glucose by the secre... more Enterobacter asburiae PSI3 solubilizes mineral phosphates in the presence of glucose by the secretion of gluconic acid generated by the action of a periplasmic pyrroloquinoline quinone dependent glucose dehydrogenase. In order to achieve mineral phosphate solubilization phenotype in the presence of sucrose, plasmids pCNK4 and pCNK5 containing genes encoding the invertase enzyme of Zymomonas mobilis (invB) and of Saccharomyces cerevisiae (suc2) under constitutive promoters were constructed with malE signal sequence (in case of invB alone as the suc2 is secreted natively). When introduced into E. asburiae PSI3, E. a. (pCNK4) and E. a. (pCNK5) transformants secreted 21.65 ± 0.94 and 22 ± 1.3 mM gluconic acid, respectively, in the presence of 75 mM sucrose and they also solubilized 180 ± 4.3 and 438 ± 7.3 µM P from the rock phosphate. In the presence of a mixture of 50 mM sucrose and 25 mM glucose, E. a. (pCNK5) secreted 34 ± 2.3 mM gluconic acid and released 479 ± 8.1 µM P. Moreover, i...

Die Naturwissenschaften, 2016

The Escherichia coli phytase gene appA encoding enzyme AppA was cloned in a broad host range plas... more The Escherichia coli phytase gene appA encoding enzyme AppA was cloned in a broad host range plasmid pBBR1MCS2 (lac promoter), termed pVA1, and transformed into the Ensifer meliloti 1020. Transformation of pVA1 in Ensifer meliloti {E. m (pVA1)} increased its phosphatase and phytase activity by ∼9- and ∼50-fold, respectively, compared to the transformants containing empty plasmid as control {E. m (pBBR1MCS2)}. The western blot experiments using rabbit anti-AppA antibody showed that AppA is translocated into the periplasm of the host after its expression. Ensifer meliloti harboring AppA protein {E. m (pVA1)} and {E. m (pBBR1MCS2)} could acidify the unbuffered phytate minimal media (pH 8.0) containing Ca-phytate or Na-phytate as sole organic P (Po) source to below pH 5.0 and released P. However, both {E. m (pVA1)} and {E. m (pBBR1MCS2)} neither dropped pH of the medium nor released P when the medium was buffered at pH 8.0 using Tris-Cl, indicating that acidification of medium was impor...

Technological Challenges and Developmental Trends, 2016

Enterobacter sp. C1D is a multi-metal tolerant plant growth promoting bacterium. Aim of the prese... more Enterobacter sp. C1D is a multi-metal tolerant plant growth promoting bacterium. Aim of the present work was to understand the effect of Cd induced morphological changes on Vigna radiata root and the influence of Enterobacter sp. C1D on root development. The experiments were conducted under hydroponics in which germinated seedlings of Vigna radiata exposed to a range of different Cd concentrations to determine IC 50 , Cd accumulation, and cell death. Hematoxylin staining revealed that Cd accumulation was deceased by 90% using bacterial treatment. A novel dual agar plate method has been developed in which one side of the germinated seedling is exposed to Cd containing medium, while another side is without Cd. This method allows the visualization of the effect of Cd on the overall growth of the plant as well as on the tissues directly exposed to Cd as compared to the unexposed tissues of the same plant. In this method bacterial effect can be studied by incorporating the culture in the medium. Cd was found to inhibit overall root elongation and negatively influences root anatomy and lateral root development. Some clear morphological responses observed were: (i) the roots were quite sensitive as the root apex tends to turn towards no Cd zone, (ii) higher numbers of lateral roots were seen on the side of Cd free medium, (iii) microscopic images of transverse section of the root showed Cd mediated damages on one side of the root, (iv) phloroglucinol staining of the section showed high lignin formation only one side of the root. On the other hand coinoculation with bacterium Enterobacter sp. C1D alleviated Cd stress. Numbers and length of lateral roots were much higher as compared to uninoculated control.

Applied Soil Ecology, 2016

Bacteria in Agrobiology: Plant Nutrient Management, 2011

Page 1. Chapter 6 Role of Siderophores in Crop Improvement Anjana Desai and G. Archana 6.1 Introd... more Page 1. Chapter 6 Role of Siderophores in Crop Improvement Anjana Desai and G. Archana 6.1 Introduction ... A. Desai (*) G. Archana Department of Microbiology, MS University of Baroda, Vadodara 390002, India e-mail: desai_aj@yahoo.com ...

Journal of Microbiological Methods, 2012

The members of the genus Deinococcus are extensively studied because of their exemplary radiation... more The members of the genus Deinococcus are extensively studied because of their exemplary radiation resistance. Both ionizing and non-ionizing rays are routinely employed to select upon the radiation resistant deinococcal population and isolate them from the majority of radiation sensitive population. There are no studies on the development of molecular tools for the rapid detection and identification of deinococci from a mixed population without causing the bias of radiation enrichment. Here we present a Deinococcus specific two-step hemi-nested PCR for the rapid detection of deinococci from environmental samples. The method is sensitive and specific to detect deinococci without radiation exposure of the sample. The new protocol was successfully employed to detect deinococci from several soil samples from different geographical regions of India. The PCR method could be adapted to a three-step protocol to study the diversity of the environmental deinococcal population by denaturing gradient gel electrophoresis (DGGE). Sequence analysis of the DGGE bands revealed that the samples harbor diverse populations of deinococci, many of which were not recovered by culturing and may represent novel clades. We demonstrate that the genus specific primers are also suitable for the rapid identification of the bacterial isolates that are obtained from a typical radiation enrichment isolation technique. Therefore the primers and the protocols described in this study can be used to study deinococcal diversity from environmental samples and can be employed for the rapid detection of deinococci in samples or identifying pure culture isolates as Deinococcus species.

Contemporary Clinical Dentistry, 2013

Background: Microorganisms are the primary causative agents of endodontic infections. Phenotype b... more Background: Microorganisms are the primary causative agents of endodontic infections. Phenotype based procedures for bacterial identification has certain drawbacks especially, when investigating the microbiota of root-filled teeth. Thus, more sensitive methods like Polymerase chain reaction (PCR) can provide results that are more accurate and reliable for the microbial prevalence in the root filled teeth. Aim: In this study, we have investigated twenty symptomatic root-filled teeth with chronic apical periodontitis for the prevalence of Enterococcus faecalis and Candida albicans in the root filled teeth associated with symptomatic cases with or without periradicular lesions. Materials and Methods: Microbiological samples were taken from the canals immediately after removal of previous gutta percha cones using aseptic techniques. After removal of root canal filling, samples were obtained with paper points placed in the canal. Paper points were transferred to a cryotube containing "Tris EDTA" buffer and immediately frozen at −20°C. Results: By PCR amplification of the samples using taxon specific primers, E. faecalis was found to be prevalent species, detected in 65% of the cases and C. albicans was detected in 35% of cases. Conclusion: The results of the study shows that geographical influence and dietary factors might have some role to play in the prevalence of the species like C. albicans and presence of E. faecalis confirming the assertion of previous culture-dependent and independent approaches for the microbiological survey of root filled teeth.