J. C. Tarafdar

Comparative efficiency of acid phosphatase originated from plant and fungal sources

A study was conducted to demonstrate the comparative efficiency of acid phosphatase generated by plants or fungi towards the hydrolysis of different organic P compounds present in soil. The results revealed that acid phosphatases were most efficient in the hydrolysis of glycerophosphate followed by lecithin and phytin. The P release increased with increase in enzyme concentration. Acid phosphatase generated from fungal sources showed three times greater efficiency in the hydrolysis of phytin, two times greater efficiency in hydrolysis of lecithin than plant phosphatase. Both sources were at par in hydrolyzing glycerophosphate. The results suggest that acid phosphatase generated from plant and fungal sources is different and microbial acid phosphatase to be more efficient than that from plant sources.

A biomimetic approach towards synthesis of zinc oxide nanoparticles

Using natural processes as inspiration, the present study demonstrates a positive correlation between zinc metal tolerance ability of a soil fungus and its potential for the synthesis of zinc oxide (ZnO) nanoparticles. A total of 19 fungal cultures were isolated from the rhizospheric soils of plants naturally growing at a zinc mine area in India and identified on the genus, respectively the species level. Aspergillus aeneus isolate NJP12 has been shown to have a high zinc metal tolerance ability and a potential for extracellular synthesis of ZnO nanoparticles under ambient conditions. UV–visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction analysis, transmission electron microscopy, and energy dispersive spectroscopy studies further confirmed the crystallinity, morphology, and composition of synthesized ZnO nanoparticles. The results revealed the synthesis of spherical nanoparticles coated with protein molecules which served as stabilizing agents. Investigations on the role of fungal extracellular proteins in the synthesis of nanoparticles indicated that the process is nonenzymatic but involves amino acids present in the protein chains.

TiO2 nanoparticle biosynthesis and its physiological effect on mung bean (Vigna radiata L.)

TiO2 nanoparticle (NPs) biosynthesis is a low cost, ecofriendly approach developed using the fungi Aspergillus flavus TFR 7. To determine whether TiO2 NPs is suitable for nutrient, we conducted a two part study; biosynthesis of TiO2 NP and evaluates their influence on mung bean. The characterized TiO2 NPs were foliar sprayed at 10 mgL−1 concentration on the leaves of 14 days old mung bean plants. A significant improvement was observed in shoot length (17.02%), root length (49.6%), root area (43%), root nodule (67.5%), chlorophyll content (46.4%) and total soluble leaf protein (94%) as a result of TiO2 NPs application. In the rhizosphere microbial population increased by 21.4–48.1% and activity of acid phosphatase (67.3%), alkaline phosphatase (72%), phytase (64%) and dehydrogenase (108.7%) enzyme was observed over control in six weeks old plants owing to application of TiO2 NPs. A possible mechanism has also been hypothesized for TiO2 NPs biosynthesis.

Nanotechnology: Interdisciplinary science of applications

Nanotechnology is the study of particle sizes between 1 and 100 nanometers at least at one dimension. Particle size reduced to nanometer length scale exhibit more surface area to volume size ratio and showing unusual properties makes them enable for systematic applications in engineering, biomedical, agricultural and allied sectors. Nanomaterial can create from bottom up or top down approaches using physical, chemical and biological mode of synthesis. Keywords: Nanotechnology, nanomaterial, nanobiotechnology, nanotech-applications African Journal of Biotechnology Vol. 12(3), pp. 219-226

Enhancing the Mobilization of Native Phosphorus in the Mung Bean Rhizosphere Using ZnO Nanoparticles Synthesized by Soil Fungi

Phosphorus (P) is a limiting factor to plant growth and productivity in almost half of the worlds arable soil, and its uptake in plants is often constrained because of its low solubility in the soil. To avoid repeated and large quantity application of rock phosphate as a P fertilizer and enhance the availability of native P acquisition by the plant root surface, in this study a biosynthesized ZnO nanoparticle was used. Zn acts as a cofactor for P-solubilizing enzymes such as phosphatase and phytase, and nano ZnO increased their activity between 84 and 108%. The level of resultant P uptake in mung bean increased by 10.8%. In addition, biosynthesized ZnO also improves plant phenology such as stem height, root volume, and biochemical indicators such as leaf protein and chlorophyll contents. In the rhizosphere, increased chlorophyll content and root volume attract microbial populations that maintain soil biological health. ICP-MS results showed ZnO nanoparticles were distributed in all plant parts, including seeds. However, the concentration of Zn was within the limit of the dietary recommendation. To the best of our knowledge, this is the first holistic study focusing on native P mobilization using ZnO nanoparticles in the life cycle of mung bean plants.

Relative efficiency of fungal intra- and extracellular phosphatases and phytase

A comparison of intra- and extracellular acid phosphatase, alkaline phosphatase and phytase activity in six fungi is reported. A strong linear relationship between intra versus extracellular fungal acid phosphatase (R2 = 0.94), alkaline phosphatase (R2 = 0.96), and phytase (R2 = 0.97) is observed. Three-fourth of acid phosphatase were generally present inside the fungal cells and only 25 % were released extracellularly after a three weeks period. Phytase shows the reverse trend where thirty nine times higher extracellular phytase activity was noticed than present inside the fungal cells. The extracellular enzymes are found 60 % more efficient in the hydrolysis of phytin than their intracellular counterpart but they are at par in the hydrolysis of glycerophosphate. The results clearly demonstrated that phytase types of phosphatases mostly occur outside the fungal cells whereas most of the acid phosphatase and alkaline phosphatase are located inside the cells. Relative Effizienz intra- und extrazellularer Phosphatasen und Phytasen in Pilzen Es wird uber einen Vergleich intra- und extrazellularer saurer bzw. alkalischer Phosphatasen (Pase) sowie Phytasen in 6 Pilzstammen berichtet. Es konnten jeweils enge lineare Beziehungen gefunden werden zwischen intra- und extrazellularen sauren Pasen (R2 = 0,94), alkalischen Pasen (R2 = 0,96) und Phytasen (R2 = 0,97). 75 % der Pasen waren im allgemeinen in den Zellen lokalisiert, lediglich 25 % wurden extrazellular freigesetzt. Phytase hingegen zeigte eine 39-fach hohere extrazellulare als intrazellulare Aktivitat. Wahrend in der Hydrolyse von Glycerophosphat kein Unterschied zwischen intra- und extrazellularen Enzymen bestand, waren bei der Hydrolyse von Phytat die extrazellularen Enzyme um 60 % effektiver. Die Ergebnisse belegen, dass die Pasen vom Typ der Phytasen vorwiegend ausserhalb der Zelle vorkommen, die sauren bzw. alkalischen Pasen jedoch sind besonders in der Zelle lokalisiert.

Rapid, Low-Cost, and Ecofriendly Approach for Iron Nanoparticle Synthesis Using Aspergillus oryzae TFR9

Development of reliable and ecofriendly green approach for synthesis of metallic nanoparticles biologically is an important step in the field of application of nanoscience and nanotechnology. The present paper reports the green approach for iron nanoparticle synthesis using Aspergillus oryzae TFR9 using FeCl3 as a precursor metal salt. Valid characterization techniques employed for biosynthesized iron nanoparticles including dynamic light scattering (DLS), transmission electron microscopy (TEM), and high resolution-transmission electron microscopy (HR-TEM) for morphological study. X-ray energy dispersive spectroscopy (EDS) spectrum confirmed the presence of elemental iron signal in high percentage. Apart from ecofriendliness and easy availability, low-cost biomass production will be more advantageous when compared to other chemical methods. Biosynthesis of iron nanoparticles using fungus has greater commercial viability that it may be used in agriculture, biomedicals and engineering sector.

Fluorescein Diacetate: A Potential Biological Indicator for Arid Soils

A field study was undertaken to identify a potential biological indicator for arid soils. The study area covered five districts (111,681 km2) in which annual rainfall varied from 217 to 427 mm and soil texture ranged from sandy to clay loam. The surface 30 cm of arid soil from agricultural field sites differing in soil properties and cropping pattern were used in the study. Soil physicochemical, microbiological, and biochemical parameters (pH, EC, organic C, total N, available N, total P, mineral P, available P, phosphate solubilizing bacteria, arbuscular mycorrhizal fungi, nitrifying bacteria, microbial biomass, acid and alkaline phosphatase, phytase, dehydrogenase, and fluorescein diacetate (FDA) hydrolysable enzymes) were identified as indicators of soil quality. Ten of the 12 parameters studied exhibited significant correlation between FDA hydrolysable enzyme activity and the other enzyme activities (acid phosphatase, alkaline phosphatase, phytase, dehydrogenase). A strong linear regression (R2 = 0.61; p < 0.01) between the FDA hydrolysable enzyme activity and microbial biomass was observed. The results demonstrated that FDA hydrolysable enzyme activity is a potential biological indicator of arid soils and is a better indicator than dehydrogenase activity, already considered as a biological indicator.

Penicillium purpurogenum, Unique P Mobilizers in Arid Agro-Ecosystems

A phosphatase and phytase producing fungus, Penicillium purpurogenum, was isolated and efficiency was tested in field on the enhancement of rhizosphere enzyme activities and mobilization of native unavailable phosphorus with pearl millet as a test crop in a loamy sand soil under arid environment. Seed inoculation with the fungi has significantly improved phosphatases (acid and alkaline), phytase, and dehydrogenase activities compared to uninoculated fields. The depletion of organic P was much higher than mineral and phytin P. The relative root growth (Kr) rate was greater between 28 and 35 days. The fungal contribution was significantly more than the plant contribution to the mineralization of mineral-P. However, both pearl millet and P. purpurogenum were equally competent for hydrolysis of phytin P. A significant improvement in plant biomass (30%), root length (21%), P uptake (6%), seed (19%) and straw yield (30%), and P concentration of shoot (15%), root (6%), and seed (33%) resulted from inoculation of P. purpurogenum. It was observed that P. purpurogenum can thrive well under arid-ecosystems. The fungus releases phosphatases and phytase, resulting in more solubilization/hydrolysis of soil unavailable P into plant available form, thereby enhancing the P uptake and pearl millet production in an arid environment.

Magnesium and iron nanoparticles production using microorganisms and various salts

Response of five fungi and two bacteria to different salts of magnesium and iron for production of nanoparticles was studied. Pochonia chlamydosporium, and Aspergillus fumigatus were exposed to three salts of magnesium while Curvularia lunata, Chaetomium globosum, A. fumigatus, A. wentii and the bacteria Alcaligenes faecalis and Bacillus coagulans were exposed to two salts of iron for nanoparticle production. The results revealed that P. chlamydosporium induces development of extracellular nanoparticles in MgCl2 solution while A. fumigatus produces also intracellular nanoparticles when exposed to MgSO4 solution. C. globosum was found as the most effective in producing nanoparticles when exposed to Fe2O3 solution. The FTIR analysis of the nanoparticles obtained from Fe2O3 solution showed the peaks similar to iron (Fe). In general, the species of the tested microbes were selective to different chemicals in their response for synthesis of nanoparticles. Further studies on their characterization and improving the efficiency of promising species of fungi need to be undertaken before tapping their potential as nanonutrients for plants.