Endophytic bacterium CIMAP-A7 mediated amelioration of atrazine induced phyto-toxicity in Andrographis paniculata.

The presence of atrazine, a triazine herbicide, and its residues in agriculture soil poses a serious threat to human health and environment through accumulation in edible plant parts. Hence, the present study focused on atrazine induced stress amelioration of Andrographis paniculata, an important medicinal plant, by a plant growth promoting and atrazine degrading endophytic bacterium CIMAP-A7 inoculation. Atrazine has a non-significant effect at a lower dose while at a higher dose (lower: 25 and higher: 50 mg kg-1) 22 and 36% decrease in secondary metabolite content and plant dry weight of A. paniculata was recorded, respectively. Endophyte CIMAP-A7 inoculation significantly reduced atrazine soil content, by 78 and 51% at lower and a higher doses respectively, than their respective control treatments. Inoculation of CIMAP-A7 exhibited better plant growth in terms of increased total chlorophyll, carotenoid, protein, and metabolite content with reduced atrazine content under both atrazine contaminated and un-contaminated treatments. Atrazine induced oxidative stress in A. paniculata was also ameliorated by CIMAP-A7 by reducing stress enzymes, proline, and malondialdehyde accumulation under contaminated soil conditions than un-inoculated treatments. Furthermore, the presence of atrazine metabolites deisopropylatrazine (DIA) and desethylatrazine (DEA) strongly suggests a role of CIMAP-A7 in mineralization however, the absence of these metabolites in uninoculated soil and all plant samples were recorded. These findings advocate that the amelioration of atrazine induced stress with no/least pesticide content in plant tissues by plant-endophyte co-interactions would be efficient in the remediation of atrazine contaminated soils and ensure safe crop produce.

The incorporation of lemongrass oil into chitosan-nanocellulose composite for bioaerosol reduction in indoor air.

The bioaerosols present in indoor air play a major role in the transmission of infectious diseases to humans, therefore concern about their exposure is increased recently. In this regard, the present investigation described the preparation of lemongrass essential oil (LGEO) loaded chitosan and cellulose nanofibers composites (CH/CNF) for controlling the indoor air bioaerosol. The evaluation of the inhibitory effect of the composite system on culturable bacteria of the indoor air was done at different sites (air volume from 30 m3 to 80 m3) and in different size fractions of aerosol (<0.25 µm-2.5 µm). The composite system had high encapsulation efficiency (88-91%) and citrals content. A significant reduction in culturable bacteria of aerosol (from 6.23 log CFUm-3 to 2.33 log CFUm-3) was observed in presence of cellulose nanofibers and chitosan composites. The bacterial strains such as Staphylococcus sp., Bacillus cereus, Bacillus pseudomycoides sp., Pseudomonas otitidis, and Pseudomonas sp. Cf0-3 in bioaerosols were inhibited dominantly due to the diffusion of aroma molecules in indoor air. The results indicate that the interaction of diffused aroma molecule from the composite system with bacterial strains enhanced the production of ROS, resulting in loss of membrane integrity of bacterial cells. Among different size fractions of aerosol, the composite system was more effective in finer size fractions (<0.25 µm) of aerosol due to the interaction of smaller aroma compounds with bacterial cells. The study revealed that LGEO loaded chitosan and cellulose nanofibers composites could be a good option for controlling the culturable bacteria even in small-sized respirable bioaerosol.

Biochar amendment reduced the risk associated with metal uptake and improved metabolite content in medicinal herbs.

Contaminations of heavy metals such as lead (Pb) and cadmium (Cd) in medicinal plants (MPs) not only restrict their safe consumption due to health hazards but also lower their productivity. Biochar amendments in the soil are supposed to immobilize the toxic metals, improve the soil quality and agricultural productivity. However, the impact of biochar on growth attributes, metal accumulation, pharmacologically active compounds of MPs, and health risk is less explored. An experiment was performed on three medicinal plants (Bacopa monnieri (L.), Andrographis paniculata (Burmf.) Nees, and Withaniasomnifera (L.)) grown in a greenhouse in soil co-contaminated with Pb and Cd (at two concentrations) without and with biochar amendments (2 and 4% application rates). The fractionation of Pb and Cd, plant growth parameters, stress enzymes, photosynthetic capacity, pharmacologically active compounds, nutrient content, uptake and translocation of metals, antioxidant activities, and metabolite content were examined in the three MPs. The accumulation of Pb and Cd varied from 3.25-228 mg kg1 and 1.29-20.2 mg kg-1 , respectively, in the three MPs, while it was reduced to 0.08-18 mg kg-1 and 0.03-6.05 mg kg-1 upon biochar treatments. Plants grown in Pb and Cd co-contaminated soil had reduced plant biomass (5-50% depending on the species) compared to control and a deleterious effect on photosynthetic attributes and protein content. However, biochar amendments significantly improved plant biomass (21-175%), as well as photosynthesis attributes, chlorophyll, and protein contents. Biochar amendments in Pb and Cd co-contaminated soil significantly reduced the health hazard quotient (HQ) estimated for the consumption of these medicinal herbs grown on metal-rich soil. An enhancement in secondary metabolite content and antioxidant properties was also observed upon biochar treatments. These multiple beneficial effects of biochar supplementation in Pb and Cd co-contaminated soil suggested that a biochar amendment is a sustainable approach for the safe cultivation of MPs. This article is protected by copyright. All rights reserved.