Environmental Sustainability

Cassava cultivation is cheap, with potential development under different climatic conditions. It is cultivated mainly in South America, Asia, and Africa. Cassava starch is an attractive feedstock, and has been employed as carbon source for production of butanol given its low cost and wide availability. In this sense, this study aimed to evaluate the production of butanol by Clostridium acetobutylicum DSMZ 792 using cassava starch as a substrate, applying Design of Experiments (DoE). Key parameters reported in the literature, such as pH and substrate concentration, were used in the evaluation trials by DoE using Rotatable Central Composite Design (RCCD) on butanol production during fermentation of cassava starch. This evaluation employed RCCD, which is a factorial scheme of treatment (22) considering four factorial design points (T1-T4), four axial points (T5-T8), and three replications on the central points (T9-T11), totaling 11 experiments. Fermentation was conducted in batch mode in 500 mL flasks, containing effective reaction volume of 300 mL. Concentrations of butanol, acetic and butyric acids were separated and analyzed by High-Performance Liquid Chromatography (HPLC) using a column (300 mm × 7.8 mm). Data were collected and analyzed using Class-VP software. The RCCD indicated that the highest butanol production is achieved in tests performed with higher concentration of the glucose, i.e., 50.0 g L−1 and with initial pH 5.7, resulting in a butanol concentration of 4.37 g L−1. The results showed that butanol production was dependent on butyric acid re-assimilation. DoE is a powerful tool for obtaining the optimum butanol concentration for determined operation condition.

Poly-γ-glutamic acid (γ-PGA) is a polymeric substance with diverse applications as thickening, anti-freezing, sticking and bitterness relieving agent. This study was aimed at utilizing cassava peels as the major substrate for production of γ-PGA by Bacillus subtilis. Pretreatment of the cassava peels was carried out using alkali, acid and organosolv methods. Effects of different carbon, nitrogen and process parameters were subjected to one-factor-at-a-time method. The raw cassava peel gave significantly (p < 0.05) higher yield of γ-PGA of 3.20 ± 0.08 mg/g when compared with all the other pretreated samples. The highest yield of γ-PGA (6.23 ± 0.13 mg/g) was obtained in a medium containing 1% (w/w) citric acid and 0.5% (w/w) (NH4)2SO4, initial moisture content 65%, inoculum concentration at 2% and incubation time of 4 days at 35 °C. Following the FTIR analysis, γ-PGA samples showed characteristic amide absorption at ~ 3753.4 cm−1, carbonyl absorption at 1600–1636.4 cm−1, and hydroxyl absorption at 3200–3276.3 cm−1. The relative viscosity (9.92 ± 0.06 mPas), and melting point (193 ± 0.04 °C) were found to be comparable with the values obtained for commercially available γ-PGA. This study demonstrates that cassava peels can be utilized as renewable raw material for production of γ-PGA by B. subtilis.

Waste biomass of Tagetes (Marigold), was used for the synthesis of bioadsorbent at two different temperatures (250 °C and 500 °C) represented as FWAC-250 and FWAC-500. Both the materials were applied for the adsorption of crystal violet (CV) dye from an aqueous solution. The characterization of bioadsorbents was done using different analytical techniques such as scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and point of zero charge (pHZPC). The synthesized bioadsorbents were found to be potent for the adsorption of crystal violet dye from an aqueous solution. Different parameters such as effect of dose, solution pH, initial CV concentration, and the operating temperature were studied for the optimization of adsorption process. The obtained experimental data were also analyzed by isotherm, kinetics, and thermodynamic studies. The results revealed that experimental data of batch adsorption study was best fitted to the Langmuir model of isotherm and the pseudo-second-order kinetics. The adsorption capacity (qmax) was found 1.95 mg/g and 2.69 mg/g for FWAC-250 and FWAC-500, correspondingly. The thermodynamic study shows that the process of CV adsorption was endothermic in nature with both biosorbents FWAC-250 and FWAC-500. The biomass waste Tagetes flowers were found to be potential candidates for the treatment of CV from an aqueous solution in a cost-effective and eco-friendly way. Thus, the bioadsorbents can be significantly used to treat wastewater contaminated with CV dye on a large scale.

Variability in carbon sequestration efficiency of different tree species in Kahinaur plantation forest of district Mau, Uttar Pradesh, India was evaluated. Moreover, improvement in nutrient status and other physicochemical characteristics of soil due to plantation forest was also taken into consideration. Soils in the plantation forest possessed higher soil organic carbon (SOC), nitrogen, phosphorus and potassium (NPK) than the adjacent waste land soil. However, nutrient status of both plantation and wasteland soil decreased with increasing soil depth and bulk density. The soil microbial biomass carbon (SMBC), soil enzyme activities like soil dehydrogenase activity, acidic and alkaline phosphates and soil respiration were higher in the plantation forest soil as compared to the waste land soil. The highest SMBC (114.47 μg g−1 soil 24 h−1) was reported in plantation forest soil, but only 56.65 μg g−1 soil 24 h−1 in waste land soil. In addition, the activity of soil dehydrogenase (2.74 μg g−1 soil h−1) was also highest in the plantation forest soil. Among the studied tree species, carbon accumulation was found maximum in Prosopis juliflora, Putranjiva roxburghii, Pithecellobium dulce and Artocarpus heterophyllus depicting that these can be recommended as atmospheric carbon reducers for their better potential to sequester and store carbon. The study indicated that afforestation or forest plantation improved SOC, nutrient stock and improved other important soil fertility parameters in the plantation forest soil as compared to the non-forest soil i.e., waste land.

In present study, novel magnetic nanocomposites based on an agro-based material, non-toxic and biocompatible xyloglucan (XG) with magnetic iron oxide (Fe3O4) were synthesized by a simple, safe and ecofriendly sonication method. The synthesized nanocomposites (XG–Fe3O4) were characterized by various analytical techniques such as powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM)-energy dispersive X-ray (EDX), transmission electron microscopy (TEM)–EDX analysis and selected-area electron diffraction (SAED). The average crystallite size of the nanocomposites as estimated by the Scherrer analysis were in the range of 17–20 nm and thus exhibited no significant difference in mean particle size on changing the ratios of Fe3O4 and Xyloglucan. The high resoloution (HR) TEM analysis revealed nanorod like shape of synthesized Fe3O4 nanoparticles. Lattice fringes of the individual crystallites were seen in the HRTEM image, indicative of their good crystallinity. The distance of 0.29 nm was found in between the lattice fringes that confirmed the cubic structure of nanoparticles. The FTIR spectrum of nanocomposite indicated the interaction of functional groups in XG with the Fe3O4 nanoparticles at the surface. The SEM analysis revealed the average crystal size of pure Fe3O4 nanocrystals to be 22.4 nm. The SAED analysis revealed that the nanocomposites (20 nm) were very close to behaving as superparamagnets at room temperature. A preliminary study on removal of methylene blue (MB) dye from aqueous solution indicated that the nanocomposite has potential to be used for photocatalytic and adsorptive removal of MB from aqueous solutions.

Pesticide degrading bacteria that are isolated from agricultural soils are known to harbor multiple auxiliary characteristics such as production of phytohormone, solubilization of inorganic phosphate, nitrogen fixation, biosurfactant production etc., which are essential for plant growth promotion. In this study, twenty bacterial cultures were isolated from different agricultural fields of Odisha, West Bengal and Manipur (three States of eastern India) by enrichment culture method. These bacteria were isolated based on their ability to grow in media containing mineral salt with lindane at the concentration of 100 mg L−1 as the only carbon utilization source. Along with lindane degradation capacity, the ability of the isolates to promote plant growth was characterized by evaluating their ability for production of ammonia, phytohormones and biosurfactants, solubilization of inorganic phosphates and nitrogen fixation. Preliminary identification of all the isolates was done by morphological as well as biochemical tests. Among the 20 isolates, 8 were found to be Gram−positive and 12 were Gram-negative. The percentage of isolates positive for solubilization of inorganic phosphate, nitrogen fixation, production of indole-3-acetic acid, biosurfactant (in CTAB-methylene blue agar and by hemolysis test in blood agar) and ammonia were 40, 70, 90, 70, 85 and 100% respectively. Finally, three isolates were selected which showed positive results for majority of the tested attributes and identified on the basis of their 16S rRNA gene sequences. It was observed that all the three isolates belonged to the genus Ochrobactrum. Hence it was concluded that along with pesticide utilization these isolates have properties for plant growth promotion and can be potent agents for raising the yield of crops in pesticide-contaminated soils by bioaugmentation.

The ecological activities within the hyporheic zone (HZ) heavily rely on water flow dynamics. The arrangement of the hyporheic community is influenced significantly by the hydrological fluxes occurring within the zone, particularly driven by the dynamics of watercourse surface flow. While there is an ongoing debate, it is suggested that benthic organisms may utilize the HZ as a sanctuary. The ability of stream organisms to colonize the HZ is influenced by their biological characteristics. Lower oxygen levels and reduced pore space in deeper sediment layers restrict the presence of macroinvertebrates while favoring meiofauna and protists. Limited research has been conducted on the overall role of hyporheos in the assembly of entire ecosystems, with most studies focusing on larger species. The metabolism of the hyporheos facilitates the transformation of pollutants and nutrients within the HZ through the action of biofilms that degrade dissolved substances, including contaminants. Lastly, the community that feeds on biofilms and participates in hyporheic exchange flow indirectly contributes to these processes. The aim of this review article is to highlight the critical role of water flow dynamics in the hyporheic zone and its influence on the arrangement of the ecological community within. It emphasizes the potential sanctuary function of the hyporheic zone for benthic organisms, shaped by their biological characteristics.