Chromium phytoextraction and physiological responses of the hyperaccumulator Leersia hexandra Swartz to plant growth-promoting rhizobacterium inoculation

Phytoextraction is a promising option for purifying hexavalent chromium(Cr(Ⅵ))-laden wastewater,but the long remediation period incurred by poor growth rate of Cr hyperaccumulators remains a primary hindrance to its large-scale application.In this study,we performed a hydroponic experiment to evaluate the feasibility of promoting the growth and phytoextraction efficiency of Cr hyperaccumulator Leersia hexandra Swartz(L.hexandra)by inoculating plant growth-promoting rhizobacteria(PGPR)Bacillus cereus(B.cereus).In batch tests,the Cr(Ⅵ)removal rates of L.hexandra and B.cereus co-culture were greater than the sum of their respective monocultures.This was likely due to the microbial reduction of Cr(Ⅵ)to Cr(Ⅲ),which is amiable to plant uptake.Besides,the PGPR factors of B.cereus,including indoleacetic acid(IAA)production,1-aminocyclopropane-1-carboxylic acid deamination(ACCd)activity,phosphate solubilization capacity,and siderophore production,were quantified.These PGPR factors helped explain the biomass augmentation,root elongation and enhanced Cr enrichment of the inoculated L.hexandra in pot experiments.Despite the increased Cr uptake,no aggravated oxidative damage to the cell membrane was observed in the inoculated L.hexandra.This was attributed to its capacity to confront the increased intracellular Cr stress by upregulating both the activities of antioxidative enzymes and expression of metal-binding proteins/peptides.Moreover,L.hexandra could always conserve the majority of Cr in the residual and oxalic integrated forms with low mobility and phytotoxicity,irrespective of the B.cereus inoculation.These results highlight the constructed Cr hyperaccumulatorrhizobacteria consortia as an effective candidate for decontaminating Cr(Ⅵ)-laden wastewater.

From agricultural cellulosic waste to food delivery packaging: A mini-review

The growing food delivery service market has boosted the consumption of packaging materials, and this trend is projected to continue in the following years. The gap between industrial supply and consumer demand from a sustainable viewpoint leads to a need for agricultural cellulosic waste-based materials that bring the idea of trash-to-treasure to fruition. In this paper, we review up-to-date advancements surrounding the food delivery packaging that are derived from agricultural cellulosic waste. Two scenarios in which agricultural feedstock is used as a host or guest material are summarized, and sketch on the individual processing routine is depicted. We further evaluate how the chemical compositions and processing parameters influence the properties of the final products. Current challenges and gaps in developing sustainable packaging materials are identified, with perspectives on these important issues highlighting the importance of process innovation as well as economic and environmental-impact assessment for agricultural cellulosic waste to food delivery packaging.