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The objective of the study was to evaluate role of zeolite and Enterobacter sp. MN17 on Cd uptake, growth, physiological and biochemical responses of Brassica napus on Cd-contaminated soil. A sandy clay loam soil in plastic pots was spiked with Cd (0 and 80 mg kg-1) and amended with zeolite (0 and 10 g kg-1). Seeds of B. napus were inoculated with Enterobacter sp. MN17. Both inoculated and non-inoculated seeds of B. napus were sown and plants were harvested after 60 days of growth and data were collected. Although sole application of zeolite and seed inoculation reverted adverse effects of Cd in B. napus plants, the combined use resulted in even higher growth and physiological responses compared to control plants. The combined use under Cd stress increased plant height, root length, dry biomass of shoot and root up to 32%, 57%, 42% and 64%, respectively compared to control. The different physiological attributes (photosynthetic rate, chlorophyll content, transpiration rate, stomatal conductance) of B. napus were improved from 6% to 137%. Moreover, combined use of zeolite and seed inoculation on Cd-contaminated soil reduced the stress to plants as antioxidant activities decreased up to 25–64%, however enzyme activities were still higher than plants grown on normal soil. Root and shoot analysis of B. napus for Cd content depicted that zeolite and bacterium decreased Cd uptake from soil. It is concluded that combined use of zeolite and strain MN17 reduces Cd uptake from soil and improves physiological and biochemical responses of B. napus which is helpful to alleviate Cd toxicity to plants.

Bio-activated organic fertilizers (BOZ) were produced by enriching the zinc oxide (ZnO)-orange peel waste composite with Zn solubilizing bacteria (ZSB: Bacillus sp. AZ6) in various formulations (BOZ1 (9:1), BOZ2 (8:2), BOZ3 (7:3) and BOZ4 (6:4)). The produced BOZs, along with ZnO, ZnSO4, ZSB were applied to maize crop (Zea mays L.) under field conditions in two different cropping season and the growth, yield, physiology, plant Zn contents and quality of maize were investigated. Results revealed significant variation in the aforementioned parameters with the applied amendments. The BOZ4 performed outclass by exhibiting the highest plant growth, yield, physiology, Zn contents, and quality. On average, an increase of 53%, 49%, 19%, 22%, 10%, 4%, and 30% in plant height was noticed with BOZ4 application over control, ZnO, ZnSO4, BOZ1, BOZ2, BOZ3, and ZSB, respectively. BOZ4 enhanced the dry shoot-biomass 46% than control. Likewise, the photosynthetic rate, transpiration rate, stomatal conductance, chlorophyll contents, carotenoids, and carbonic anhydrase activity were increased by 47%, 42%, 45%, 57%, 17%, and 44%, respectively, under BOZ4 over control in both cropping seasons. However, BOZ4 reduced the electrolyte leakage by 38% as compared to control in both cropping seasons. BOZ4 increased the Zn contents of grain and shoot by 46% and 52%, respectively, while reduced the phytate contents by 73% as compared to control. Application of BOZ4 revealed highest average fat (4.79%), crude protein (12.86%), dry matter (92.03%), fiber (2.87%), gluten (11.925%) and mineral (1.53%) contents, as compared to control. In general, the impact of cropping seasons on maize growth, yield, physiology, Zn contents, and quality were non-significant (with few exceptions). Thus, bio-activation of ZnO with ZSB could serve as an efficient and economical strategy for boosting up the growth, yield, physiological, and quality parameters of maize under field conditions.

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How to sustainably feed a growing global population is a question still without an answer. Particularly farmers, to increase production, tend to apply more fertilizers and pesticides, a trend especially predominant in developing countries. Another challenge is that industrialization and other human activities produce pollutants, which accumulate in soils or aquatic environments, contaminating them. Not only is human well-being at risk, but also environmental health. Currently, recycling, land-filling, incineration and pyrolysis are being used to reduce the concentration of toxic pollutants from contaminated sites, but too have adverse effects on the environment, producing even more resistant and highly toxic intermediate compounds. Moreover, these methods are expensive, and are difficult to execute for soil, water, and air decontamination. Alternatively, green technologies are currently being developed to degrade toxic pollutants. This review provides an overview of current research on microbial inoculation as a way to either replace or reduce the use of agrochemicals and clean environments heavily affected by pollution. Microorganism-based inoculants that enhance nutrient uptake, promote crop growth, or protect plants from pests and diseases can replace agrochemicals in food production. Several examples of how biofertilizers and biopesticides enhance crop production are discussed. Plant roots can be colonized by a variety of favorable species and genera that promote plant growth. Microbial interventions can also be used to clean contaminated sites from accumulated pesticides, heavy metals, polyaromatic hydrocarbons, and other industrial effluents. The potential of and key processes used by microorganisms for sustainable development and environmental management are discussed in this review, followed by their future prospects.