Evaluation of nineteen food wastes for essential and toxic elements

Abstract Purpose The study evaluates and provides an overview of the nutritional importance of 19 selected food wastes as aids in human/livestock/soil/plant health. Methods Nitric acid-digested extracts of food wastes belonging to four different classes (fruits, vegetables, oilseeds and beverages) were analysed for different elements in an inductively coupled plasma mass spectrometer. Results Our study recommends spent coffee grounds, tea leaves, radish peel, watermelon rind and pineapple skin that contain substantially high concentrations of essential elements such as N, P, K, S and Fe for their use as: (a) substrates for composting, (b) biofertilizers, (c) soil amendments, and (d) bioadsorbents of toxins. Although these food wastes are rich in essential nutrients, we do not suggest them for the preparation of food supplements as they contain non-essential elements in concentrations beyond the human safety limits. However, food wastes like banana peel, plum pomace and pistachio shell that contain low and permissible concentrations of toxic elements can be recommended as dietary supplements for oral intake in spite of their lesser essential elemental composition than the other residues examined. Conclusions Our study confirms that food wastes are rich sources of essential nutrients and there is need to harness their real industrial systems

Sustainability Evaluation of Immobilized Acid-Adapted Microalgal Technology in Acid Mine Drainage Remediation following Emergy and Carbon Footprint Analysis

Sustainability evaluation of wastewater treatment helps to reduce greenhouse gas emissions, as it emphasizes the development of green technologies and optimum resource use rather than the end-of-pipe treatment. The conventional approaches for treating acid mine drainages (AMDs) are efficient; however, they need enormous amounts of energy, making them less sustainable and causing greater environmental concern. We recently demonstrated the potential of immobilized acid-adapted microalgal technology for AMD remediation. Here, this novel approach has been evaluated following emergy and carbon footprint analysis for its sustainability in AMD treatment. Our results showed that imported energy inputs contributed significantly (>90%) to the overall emergy and were much lower than in passive and active treatment systems. The microalgal treatment required 2–15 times more renewable inputs than the other two treatment systems. Additionally, the emergy indices indicated higher environmental loading ratio and lower per cent renewability, suggesting the need for adequate renewable inputs in the immobilized microalgal system. The emergy yield ratio for biodiesel production from the microalgal biomass after AMD treatment was >1.0, which indicates a better emergy return on total emergy spent. Based on greenhouse gas emissions, carbon footprint analysis (CFA), was performed using default emission factors, in accordance with the IPCC standards and the National Greenhouse Energy Reporting (NGER) program of Australia. Interestingly, CFA of acid-adapted microalgal technology revealed significant greenhouse gas emissions due to usage of various construction materials as per IPCC, while SCOPE 2 emissions from purchased electricity were evident as per NGER. Our findings indicate that the immobilized microalgal technology is highly sustainable in AMD treatment, and its potential could be realized further by including solar energy into the overall treatment system

Construction of Escherichia coli Strains for Conversion of Nitroacetophenones to ortho-Aminophenols

The predominant bacterial pathway for nitrobenzene (NB) degradation uses an NB nitroreductase and hydroxylaminobenzene (HAB) mutase to form the ring-fission substrate ortho-aminophenol. We tested the hypothesis that constructed strains might accumulate the aminophenols from nitroacetophenones and other nitroaromatic compounds. We constructed a recombinant plasmid carrying NB nitroreductase (nbzA) and HAB mutase A (habA) genes, both from Pseudomonas pseudoalcaligenes JS45, and expressed the enzymes in Escherichia coli JS995. IPTG (isopropyl-β-d-thiogalactopyranoside)-induced cells of strain JS995 rapidly and stoichiometrically converted NB to 2-aminophenol, 2-nitroacetophenone (2NAP) to 2-amino-3-hydroxyacetophenone (2AHAP), and 3-nitroacetophenone (3NAP) to 3-amino-2-hydroxyacetophenone (3AHAP). We constructed another recombinant plasmid containing the nitroreductase gene (nfs1) from Enterobacter cloacae and habA from strain JS45 and expressed the enzymes in E. coli JS996. Strain JS996 converted NB to 2-aminophenol, 2-nitrotoluene to 2-amino-3-methylphenol, 3-nitrotoluene to 2-amino-4-methylphenol, 4-nitrobiphenyl ether to 4-amino-5-phenoxyphenol, and 1-nitronaphthalene to 2-amino-1-naphthol. In larger-scale biotransformations catalyzed by strain JS995, 75% of the 2NAP transformed was converted to 2AHAP, whereas 3AHAP was produced stoichiometrically from 3NAP. The final yields of the aminophenols after extraction and recovery were >64%. The biocatalytic synthesis of ortho-aminophenols from nitroacetophenones suggests that strain JS995 may be useful in the biocatalytic production of a variety of substituted ortho-aminophenols from the corresponding nitroaromatic compounds.

Solar technology‒closed loop synergy facilitates low-carbon circular bioeconomy in microalgal wastewater treatment

Abstract The circular bioeconomy framework addresses the global transition toward resource-efficient and low-carbon economies. The use of microalgae in sustainable circular bioeconomy largely suffers from energy consumption and underutilization of residual biomass, leading to greenhouse gas (GHG) emissions. This analysis-based perspective reveals that closed loop microalgal wastewater systems reduce GHG emissions by >50% and enhance valorization of residual biomass for value-added products compared to open loop approach. Integrating solar technologies in closed loop system further reduces GHG emissions by 99% and aligns with 11 UN sustainable development goals, making it a suitable model for a zero-waste and low-carbon circular bioeconomy

Risks of veterinary antibiotics contamination in Indian organic farmlands: A reality unfolded

Globally, the widespread use of antibiotics in intensive animal farming has contributed to their increased environmental burden. Notably, data and knowledge on these contaminants in farmlands are lacking in India, despite being a major agricultural producer worldwide. To date, no studies have explored whether antibiotics are an intractable environmental issue in Indian agroecosystems. Specifically, information on the prevalence and spread of common antibiotics in long-term animal manure-laden organic farmlands of India is non-existent. Here, we examined samples of manure, soil and vegetables collected from 24 different organic farmlands in India to assess the presence of residues from 15 typical veterinary antibiotics (VAs). Our findings revealed that nine VAs, including three tetracyclines (TCs), three sulfonamides (SAs), one macrolide (ML), and two quinolones (QNs), were recorded in almost all the manure and soil samples. The residual levels of antibiotics (µg kg‒1) decreased in the following order: TCs (manure: 22.10‒161.10; soil: 8.30‒61) > SAs (manure: 0.90‒73; soil: 0.20‒48.40) > QNs (manure: nd‒3.60; soil: nd‒1.80) > MLs (manure: nd‒1.50; soil: nd‒0.90). Poultry manure-applied farmlands exhibited the highest antibiotic contamination levels, with total antibiotic concentrations surpassing the ecotoxicological effect trigger value of 100 μg kg−1 set by the Steering Committee of the Veterinary International Committee on Harmonization, highlighting the potential hazard of VAs to the soil ecosystem. The translocation of VAs in vegetables was in the order: leaf > root > fruit, and bioaccumulation of 0.10‒3.90 μg kg−1 was recorded. Notably, the calculated risk quotients of antibiotics in vegetables were ˂1, indicating the negligible risk to human health. Overall, our study unveils a concerning state of VAs pollution in organic farmlands in India that warrants special attention, as it may contribute to the proliferation of antibiotic resistance

The impacts of environmental pollutants on microalgae and cyanobacteria

Efforts are continuously being made to understand the non-target effects of environmental pollutants toward microalgae and cyanobacteria because of their ubiquity in aquatic and terrestrial environments and their highly adaptive survival abilities under environmental and evolutionary pressure over geological time. Depending on the toxicity criteria employed for these ecologically beneficial organisms, the impact of low and high doses of pollutants can range from stimulation to total inhibition. All of the investigations carried out so far have been predominantly concerned with individual chemicals despite the occurrence of pollutants in mixtures. In addition, only individual isolates have been primarily used to gather scientific information on the toxicity of pollutants. The risk assessment of pollutants toward these organisms necessitates further investigations, combining innovative molecular ecological methods and those for in situ analysis at the community level. The present review highlights the toxic influences of organic and inorganic pollutants and the response in terms of detoxification and resistance by these organisms