Plant growth-promoting bacterial consortia improved the physiology and growth of maize by regulating osmolytes and antioxidants balance under salt-affected field conditions.

This study was undertaken to see how microbial consortia influenced maize development and yield under salt-affected conditions. The efficacy of the pre-isolated bacterial strains Burkholderia phytofirmans, Bacillussubtilis, Enterobacter aerogenes, and Pseudomonas syringae and Pseudomonas fluorescens to decrease the detrimental effects of salt on maize was tested in four distinct combinations using Randomized Complete Block Design with three replicates. The results revealed that these strains were compatible and collaborated synergistically, with an 80% co-aggregation percentage under salt-affected conditions. Following that, these strains were tested for their ability to increase maize growth and yield under salt-affected field conditions. The photosynthetic rate (11-50%), relative water content (10-34%), and grain yield (13-21%) of maize were all increased by these various combinations. However, when Burkholderia phytofirmans, Enterobacter aerogenes and Pseudomonas fluorescens were combined, the greatest increase was seen above the un-inoculated control. Furthermore, as compared to the un-inoculated control, the same combination resulted in a 1.5-fold increase in catalase and a 2.0-fold increase in ascorbate concentration. These findings showed that a multi-strain consortium might boost maize's total yield response as a result of better growth under salt stress.

Converging alfalfa (Medicago sativa L.) and petroleum hydrocarbon acclimated ACC-deaminase containing bacteria for phytoremediation of petroleum hydrocarbon contaminated soil.

Plant assisted bioremediation of petroleum hydrocarbon contaminated soil is considered an effective green technology whereby accelerated degradation occurs due to converged effect of microorganisms and plants. However, survival and growth of microbes and plants under stress conditions is challenging task for success of the technology. In this study, plant growth promoting bacteria containing 1-aminocyclopropane-1-carboxylate (ACC)-deaminase activity and tolerance to petroleum hydrocarbon contamination were used in association with alfalfa for bioremediation of petroleum hydrocarbon contaminated soil. Eight pre-isolated bacterial isolates from soil having previous history of petroleum contamination were used in convergence with alfalfa on sand soil which was artificially contaminated (10 g crude oil per kg-1 of coarse textured soil). Combined effect of bacteria and plants on the degradation of petroleum hydrocarbons under controlled conditions of light and temperature was observed for a period of 60 days. The results of the study revealed that four bacterial isolates Bacillus subtilis strain PM32Y, Bacillus cereus strain WZ3S1, Bacillus sp. strain SM73 and Bacillus sp. strain WZ3S3 in association with alfalfa significantly degraded petroleum hydrocarbons. The most significant biodegradation (47%) of petroleum hydrocarbons was recorded in the experimental unit receiving PM32Y inoculation in association with alfalfa. Biodegradation of petroleum hydrocarbons was 33% with alone inoculation (without alfalfa) of PM32Y. The study revealed that combined use of bacteria and alfalfa plant is more efficient than alone application of either bacteria or plants for degradation of petroleum hydrocarbons.

This study provides the evidence for phytoremediation and significant degradation of petroleum hydrocarbons by using plant growth promoting bacteria (PGPB), containing 1-aminocyclopropane-1-carboxylate deaminase (ACC-deaminase) in association with alfalfa (Medicago sativa L.). The most significant biodegradation of petroleum hydrocarbons was recorded with a new combination of Bacillus subtilis strain PM32Y in association with alfalfa.

Potential of plant growth promoting bacterial consortium for improving the growth and yield of wheat under saline conditions.

Owing to inconsistent results of a single bacterial strain, co-inoculation of more than one strain under salinity stress could be a more effective strategy to induce salt tolerance. Co-inoculation of more than one bacterial strain could be more effective due to the presence of several growths promoting traits. This study was conducted to evaluate the effectiveness of multi-strains bacterial consortium to promote wheat growth under salinity stress. Several plant growth promoting rhizobacteria (PGPR) had been isolated and tested for their ability to grow in increasing concentrations of sodium chloride (NaCl). Those rhizobacterial strains having tolerance against salinity were screened to evaluate their ability to promote wheat growth in the presence of salinity by conducting jar trials under axenic conditions. The rhizobacteria with promising results were tested for their compatibility with each other before developing multi-strain inoculum of PGPR. The compatible PGPR strains were characterized, and multi-strain inoculum was then evaluated for promoting wheat growth under axenic conditions at different salinity levels, i.e., 2.1 (normal soil), 6, 12, and 18 dS m-1. The most promising combination was further evaluated by conducting a pot trial in the greenhouse. The results showed that compared to a single rhizobacterial strain, better growth-promoting effect was observed when rhizobacterial strains were co-inoculated. The multi-strain consortium of PGPR caused a significant positive impact on shoot length, root length, shoot fresh weight, and root fresh weight of wheat at the highest salinity level in the jar as well as in the pot trial. Results showed that the multi-strain consortium of PGPR caused significant positive effects on the biochemical traits of wheat by decreasing electrolyte leakage and increasing chlorophyll contents, relative water contents (RWC), and K/Na ratio. It can be concluded that a multi-strain consortium of PGPR (Ensifer adhaerens strain BK-30, Pseudomonas fluorescens strain SN5, and Bacillus megaterium strain SN15) could be more effective to combat the salinity stress owing to the presence of a variety of growth-promoting traits. However, further work is going on to evaluate the efficacy of multi-strain inoculum of PGPR under salt-affected field conditions.

Phycoremediation of textile effluents with enhanced efficacy of biodiesel production by algae and potential use of remediated effluent for improving growth of wheat.

The uncontrolled industrialization and unrestricted textile production combined with inappropriate effluent treatment services in developing countries like Pakistan have multiplied the number of harmful effluent discharge. These effluents are enriched with dyes, heavy metal ions, and other hazardous materials that are poisonous and carcinogenic to living organisms. For that reason, the utilization of economic and efficient control techniques against such pollutants is imperative to protect natural resources. The triple algal role for phycoremediation of textile effluent was utilized in this study to make it suitable for irrigation and higher biofuel production. Locally isolated two strains, CKW1 (Spirogyra sp.) and PKS33 (Cladophora sp.), were used to treat the effluent collected from the direct outlets of the textile industries. The treated effluent was then tested for its toxicity and applied to wheat at initial stage grown under axenic conditions to check its effect on wheat (Triticum aestivum L.) vegetative growth and development. Finally, the algal biomass obtained after treatment was subjected to trans-esterification for predicting the amount of biodiesel production. Study outcomes revealed that the algal strains were able to decolorize the effluent entirely within 96-120 h. Compared to un-treated textile effluent, the phycoremediated wastewater application to wheat plants enhanced the plant biomass by 80%. Lastly, the production of biodiesel from algal biomass attained after phycoremediation was 35% less to algal biomass obtained under normal growth conditions. It can be concluded that the algal use helps to treat the contaminated effluent and marks them re-usable for irrigating plants and producing biomass which could be utilized for biodiesel production.

Green Fabrication of Silver Nanoparticles using Euphorbia serpens Kunth Aqueous Extract, Their Characterization, and Investigation of Its In Vitro Antioxidative, Antimicrobial, Insecticidal, and Cytotoxic Activities.

The silver nanoparticles (AgNPs) were synthesized via green synthesis approach using Euporbia serpens Kunth aqueous extract. The synthesized AgNPs were characterized by UV-visible spectroscopy and Furrier Transformer Infra-Red spectroscopy to justify the reduction and stabilization of AgNPs from its precursors. AgNPs characteristic absorption peak was observed at 420 nm in the UV-visible spectrum. The SEM and TEM analysis demonstrated the spherical shape of the synthesized nanoparticles with particle sizes ranging from 30 nm to 80 nm. FTIR transmission bands at 2920 cm-1, 1639 cm-1, 1410 cm-1, 3290 cm-1, and 1085 cm-1 were attributed to C-H, C=O, C-C, N-H, and C-N functional groups, respectively. XRD peaks could be attributed to (111), (200), (220), and (311) crystalline plane of the faced-centered cube (FCC) crystalline structure of the metallic silver nanoparticles. The AgNPs showed good antibacterial activity against all the tested bacteria at each concentration. The particles were found to be more active against Escherichia coli (E. coli) with 20 ± 06 mm and Salmonella typhi (S. typhi) with 18 ± 0.5 mm zone of inhibition in reference to standard antibiotic amoxicillin with 23 ± 0.3 mm and 20 ± 0.4 mm zone of inhibition, respectively. Moderate antifungal activities were observed against Candida albicans (C. albicans) and Alternaria alternata (A. alternata) with zone of inhibitions 16.5 mm and 15 mm, respectively, compared to the standard with 23 mm of inhibition. Insignificant antifungal inhibition of 7.5 mm was observed against Fusarium gramium (F. gramium). All the tested concentrations of AgNPs showed comparable % RSA with the standard reference ascorbic acid in the range sixty percent to seventy five percent. The percent motility at 3 hours postincubation showed quick response and most Tetramorium caespitum were found deceased or paralyzed. Similarly, the percent mortality showed a linear response at concentration and time. It was observed that 1 µg/mL to 2 µg/mL concentration of AgNPs displayed a significant cytotoxic activity against Artemia salina with LD50 of 5.37 and 5.82, respectively.

Microscopic techniques for characterization and authentication of oil-yielding seeds.

Investigation of alternative energy sources is need of current time due to growing power crisis and associated environmental issues. Biodiesel is considered as sustainable power source and promising alternative to fossil fuels. Therefore, our current investigation aimed to identify micromorphological characters of 10 novel nonedible oil-yielding seeds through scanning electron microscopy. It was revealed from light microscopic study that there is variation in seed size from 3 to 15 mm in length and 2 to 11 mm in width. Likewise, a huge variation in color was observed such as light green, greenish yellow, blackish brown, and various shades of brown. Presence and absence of Hilum was observed, and compression of seeds varied from depressed, lateral, and dorsoventral. Seed's shape differs from ovate, clavate, triangular ovate, cuneiform, ovoid, and elliptical shape. Seed oil content fall in range of 18-58% (wt/wt). Free fatty acid content of the seeds varies from 0.3 to 3.1 mg KOH/g. Ultrastructure of seeds exhibited huge variation in shape, size, periclinal wall, anticlinal wall, and surface ornamentation. Nonedible seeds varied in wall structure from angular, wavy, dentate entire, irregular, puzzled, elongated, even, and polygonal. The periclinal wall arrangements show alteration from flat, looped, raised, depressed, lofty, even, pentagonal, polygonal, and undulate seed margins. Outcomes of this investigation recommended that scanning electron microscopy could act as a helpful tool in disclosing the hidden micromorphological characters among nonedible oil-yielding seeds and subsequently helping in correct, authentic seed identification and classification as potential feedstock for biodiesel.

Implication of light and scanning electron microscopy for pollen morphology of selected taxa of family Asteraceae and Brassicaceae.

The present study was intended to assess pollen morphological attributes of selected Asteraceous and Brassicaceous species from tehsil Esa Khel (Mianwali), Punjab using scanning electron microscopy (SEM) and light microscopy (LM) techniques for its systematic and taxonomic significance for correct identification. Pollen from 12 different species belongs to two plant families from various distributional localities were collected, acetolyzed and measured. Different palynomorphological features were investigated using LM and SEM techniques. In Asteraceous species, three types of pollen (tricolporate, trizonocolporate, and tetracolporate) were observed. Pollen shape was observed prolate-spheroidal in three species while oblate and oblate-spheroidal were detected in Parthenium hysterophorus and Erigeron bonariensis. While sculpturing pattern of exine were echinate, echinate fenestrate, echinate perforate and scabrate echinate. Mesocolpium measurement was calculated maximum for Sonchus oleraceous (16.6 µm). Brassicaceae pollen were circular, lobate, tricolpate and exine show reticulate peculiarities. Whereas dominant shape was oblate-spheroidal followed by prolate-spheroidal and sub-prolate in Lepidium didymum and Sisymbrium irio, respectively. Mesocolpium distance was noted highest in Raphanus raphanistrum (14.4 µm). Exine thickness was noted maximum in Erigeron bonariensis (2.9 µm) in Asteraceous species and in Brassicaceae; Lepedium didymum exine measurement was 2.7 µm. The study showed that pollen micromorphology has important role to accurately identify and classify diverse plants genera belong to different families. Based on these taxonomic palynomorph features, the accurate identification of species from flora of tehsil Esa Khel, Mianwali were elaborated.

Effective Antiplasmodial and Cytotoxic Activities of Synthesized Zinc Oxide Nanoparticles Using Rhazya stricta Leaf Extract.

In the present study, zinc oxide (ZnO) nanoparticles were prepared using ZnCl2.2H2O as a precursor, via green route using leaf extract of Rhazya stricta as capping and reducing agent. The prepared ZnO nanoparticles were examined using UV-visible spectrophotometer (UV-Vis), Fourier transform infrared spectrometer (FT-IR), X-ray diffraction spectrometer (XRD), and scanning electron microscope (SEM). The UV-Vis absorption spectrum at 355 nm showed an absorption peak, which indicates the formation of ZnO NPs. The FT-IR spectra analysis was performed to identify the potential biomolecule of the as-prepared ZnO NPs. The FT-IR spectra showed peaks at 3455, 1438, 883, and 671 cm-1 in the region of 4000-500 cm-1, which indicates -OH, NH, C-H, and M-O groups, respectively. The SEM images showed aggregation of ZnO nanoparticles with an average size of 70-90 nm. The XRD study indicated that the ZnO NPs were crystalline in nature with hexagonal wurtzite structure and broad peaks were observed at 2 theta positions 31.8°, 34.44°, 36.29°, 47.57°, 56.61°, 67.96°, and 69.07°. The synthesized ZnO NPs were found to be good antiplasmodial with a 50% inhibitory concentration (IC50) value of 3.41 µg/mL. It is concluded from the current study that the ZnO NPs exhibited noble antiplasmodial activity, and for the improvement of antiplasmodial medications, it might be used after further in vivo studies.

Comparative evaluation of different carrier-based multi-strain bacterial formulations to mitigate the salt stress in wheat.

The application of liquid bacterial consortia to soil under natural conditions may fail due to various environmental constraints. In this study, the suitability and efficiency of compost, biogas slurry, crushed corn cob, and zeolite as carriers to support the survival of plant growth-promoting rhizobacteria (PGPR) and improve the performance of multi-strain bacterial consortia to mitigate the effects of salinity stress on wheat under pot conditions were evaluated. The survival of strains of Pseudomonas putida, Serratia ficaria, and Pseudomonas fluorescens labelled with gusA was evaluated for up to 90 days. Seeds coated with different carrier-based formulations of multi-strain consortia were sown in pots at three different salinity levels (1.53, 10, and 15 dS m-1). Results showed that salinity stress significantly reduced wheat growth, yield, gas exchange, and ionic and biochemical parameter values, but the 1-aminocyclopropane-1-carboxylate (ACC) deaminase-containing multi-strain consortium used mitigated the inhibitory effects of salinity on plant growth and yield parameters. However, carrier-based inoculation further improved the efficacy of multi-strain consortium inoculation and significantly (P < 0.05) increased the growth, yield, and physiological parameters value of wheat at all salinity levels. On the basis of the observed trends in survival and the outcomes of the pot trials, the inoculation of multi-strain consortia in compost and biogas slurry carriers resulted in more successful wheat growth under salinity stress compared to that in the rest of the treatments tested.

Soil amendments with ethylene precursor alleviate negative impacts of salinity on soil microbial properties and productivity.

Some microbes enhance stress tolerance in plants by minimizing plant ethylene levels via degradation of its immediate precursor, 1-aminocyclopropane-1-carboxylate (ACC), in the rhizosphere. In return, ACC is used by these microbes as a source of nitrogen. This mutualistic relationship between plants and microbes may be used to promote soil properties in stressful environments. In this study, we tested the hypothesis that amendments of ACC in soils reshape the structure of soil microbiome and alleviate the negative impacts of salinity on soil properties. We treated non-saline and artificially-developed saline soils with ACC in different concentrations for 14 days. The structure of soil microbiome, soil microbial properties and productivity were examined. Our results revealed that microbial composition of bacteria, archaea and fungi in saline soils was affected by ACC amendments; whereas community composition in non-saline soils was not affected. The amendments of ACC could not fully counteract the negative effects of salinity on soil microbial activities and productivity, but increased the abundance of ACC deaminase-encoding gene (acdS), enhanced soil microbial respiration, enzymatic activity, nitrogen and carbon cycling potentials and Arabidopsis biomass in saline soils. Collectively, our study indicates that ACC amendments in soils could efficiently ameliorate salinity impacts on soil properties and plant biomass production.

Nickel phytoextraction through bacterial inoculation in Raphanus sativus.

A pot experiment was conducted to evaluate the potential of two plant growth promoting rhizobacteria (PGPR) viz. Bacillus sp. CIK-516 and Stenotrophomonas sp. CIK-517Y for improving the growth and Ni uptake of radish (Raphanus sativus) in the presence of four different levels of Ni contamination (0, 50, 100, 150 mg Ni kg-1 soil). Plant growth, dry biomass, chlorophyll and nitrogen contents were significantly reduced by the exogenous application of Ni, however, bacterial inoculation diluted the negative impacts of Ni stress on radish by improving these parameters. PGPR strain CIK-516 increased root length (9-27%), shoot length (8-27%), root dry biomass (2-32%), shoot dry biomass (9-51%), root girth (6-48%), total chlorophyll (4-38%) and shoot nitrogen contents (11-15%) in Ni contaminated and non-contaminated soils. Positive regulation of chlorophyll and nitrogen contents by the inoculated plants shows plant tolerance mechanism of Ni stress. Bacterial strain (CIK-516) exhibited indole acetic acid and 1-amino-cyclopropane-1-carboxylate deaminase potentials which would have helped radish plant to stabilize in Ni contaminated soil and thereby increased Ni uptake (24-257 in shoot and 58-609 in root mg kg-1 dry biomass) and facilitated accumulation in radish (bioaccumulation factor = 0.6-1.7) depending upon soil Ni contamination. Based on the findings of this study, it might be suggested that inoculation with bacterial strain CIK-516 could be an efficient tool for enhanced Ni phytoextraction in radish.

Gibberellic acid in combination with pressmud enhances the growth of sunflower and stabilizes chromium(VI)-contaminated soil.

The present study was conducted to assess the impact of gibberellic acid on growth and yield of sunflower in hexavalent chromium [Cr(VI)]-contaminated soil in the presence as well as absence of pressmud. Seeds of sunflower were sown in potted soil amended with pressmud as an organic amendment and contaminated with different levels of Cr(VI) (12, 18, and 24 mg kg(-1)) by using K2Cr2O7 salt. Gibberellic acid (10(-4) M) was applied at time of seedling emergence in the rhizosphere. The results showed that Cr(VI) stress significantly reduced the growth and yield of sunflower. However, application of gibberellic acid and pressmud reversed the toxic effects of Cr(VI) and improved the growth and yield of sunflower. Combined application of gibberellic acid and pressmud further improved growth and yield compared to their separate application in Cr(VI) stress. Moreover, gibberellic acid and pressmud decreased the uptake of Cr and stabilized it in the soil.