Phytotoxicity test in check: Proposition of methodology for comparison of different method adaptations usually used worldwide

Combatting pesticide pollution: using liquid scintillation spectrometry to assess 14C-labeled hexachlorobenzene removal by mangrove Bacillus spp

This study explored the ability of two Bacillus species isolated from mangrove sediments to degrade hexachlorobenzene (HCB), a persistent organic pollutant that affects the quality of surface water, groundwater, and soil. Hence, we analyzed bacterial growth in a medium with hexachlorobenzene as the sole carbon source. Moreover, chemical oxygen demand removal, ecotoxicity, and measured radiolabeled HCB degradation were assessed. Our results revealed that both Bacillus strains (I3 and I6) demonstrated hexachlorobenzene-degrading potential and achieved degradation rates of 11.5 ± 1.47% and 21.1 ± 0.84%. Additionally, the ability of these strains to mineralize HCB was confirmed by the production of radiolabeled carbon dioxide, assessed by liquid scintillation spectrometry and thin-layer chromatography. Ecotoxicity assays further demonstrated the effectiveness of bacteria treatment in degrading HCB. These findings underscore the potential of Bacillus strains from mangrove sediments to degrade and mineralize HCB, opening new perspectives for the bioremediation of aromatic compounds in contaminated environments.

Production and Optimization of Biosurfactant Properties Using Candida mogii and Licuri Oil (Syagrus coronata)

Optimizing biosurfactant (BS) production is key for sustainable industrial applications. This study investigated BS synthesis by Candida mogii using licuri oil, a renewable carbon source rich in medium-chain fatty acids. Process optimization was conducted via central composite design (CCD), adjusting concentrations of licuri oil, glucose, NH4NO3, and yeast extract. The predictive model achieved an R2 of 0.9451 and adjusted R2 of 0.8812. Under optimized conditions, C. mogii lowered water surface tension from 71.04 mN·m-1 to 28.66 mN·m-1, with a critical micelle concentration (CMC) of 0.8 g·L-1. The biosurfactant displayed high emulsification indices, exceeding 70% for canola, licuri, and motor oils, suggesting strong potential as an industrial emulsifier. FTIR and NMR analyses confirmed its glycolipid structure. Bioassays showed no toxicity to Lactuca sativa seeds, ensuring environmental safety, while antimicrobial tests demonstrated efficacy against Staphylococcus aureus and Escherichia coli, indicating its suitability as a biocidal agent. This work positions C. mogii BS from licuri oil as a promising alternative for bioremediation, biotechnology, and antimicrobial uses.

Innovation for recycling of organic matter through composter with automatic and sustainable temperature recording accessed via Bluetooth/mobile app

Compost reactors, commonly used in experiments, industrial assays, and home residue treatment systems, have the potential to facilitate composting. Challenges persist in the realm of small-scale composting, encompassing facets such as temperature monitoring, homogenization of the compost mass, management of moisture with the control of leachate generation, and integration with a renewable energy source. This study assesses a pioneering composter prototype endowed with essential features to ensure a pragmatic and secure composting process. This includes the facilitation of remote access to temperature data via Bluetooth and a mobile application. Across successive trials, the scrutinized composter prototype consistently yielded reproducible outcomes, exhibiting a coefficient of variation below 25% for the majority of appraised parameters. In comparison to a conventional reactor, the decomposing residue mixture within the examined prototype manifested elevated temperatures (p < 0.05). Moreover, the tested prototype demonstrated C/N ratio lower than 20/1 within 45 days, a higher final nitrogen concentration, and enhanced germination of seeds that served as phytotoxicity bioindicators. Notably, the prototype needed 46.6% less space, offering improved leachate control, three times faster turning time, temperature monitoring, and reduced fly attraction.

Distribution, risk evaluation, and source allocation of cesium and strontium in surface soil in a mining city

Radioactive nuclides cesium (Cs) and strontium (Sr) possess long half-lives, with 135Cs at approximately 2.3 million years and 87Sr at about 49 billion years. Their persistent accumulation can result in long-lasting radioactive contamination of soil ecosystems. This study employed geo-accumulation index (Igeo), pollution load index (PLI), potential ecological risk index (PEPI), health risk assessment model (HRA), and Monte Carlo simulation to evaluate the pollution and health risks of Cs and Sr in the surface soil of different functional areas in a typical mining city in China. Positive matrix factorization (PMF) model was used to elucidate the potential sources of Cs and Sr and the respective contribution rates of natural and anthropogenic sources. The findings indicate that soils in the mining area exhibited significantly higher levels of Cs and Sr pollution compared to smelting factory area, agricultural area, and urban residential area. Strontium did not pose a potential ecological risk in any studied functional area. The non-carcinogenic health risk of Sr to the human body in the study area was relatively low. Because of the lack of parameters for Cs, the potential ecological and human health risks of Cs was not calculated. The primary source of Cs in the soil was identified as the parent material from which the soil developed, while Sr mainly originated from associated contamination caused by mining activities. This research provides data for the control of Cs and Sr pollution in the surface soil of mining city.

Bioformulation of Bacillus proteolyticus MITWPUB1 and its biosurfactant to control the growth of phytopathogen Sclerotium rolfsii for the crop Brassica juncea var local, as a sustainable approach

Bacillus proteolyticus MITWPUB1 is a potential producer of biosurfactants (BSs), and the organism is also found to be a producer of plant growth promoting traits, such as hydrogen cyanide and indole acetic acid (IAA), and a solubilizer of phosphate. The BSs were reportedly a blend of two classes, namely glycolipids and lipopeptides, as found by thin layer chromatography and Fourier-transform infrared spectroscopy analysis. Furthermore, semi-targeted metabolite profiling via liquid chromatography mass spectroscopy revealed the presence of phospholipids, lipopeptides, polyamines, IAA derivatives, and carotenoids. The BS showed dose-dependent antagonistic activity against Sclerotium rolfsii; scanning electron microscopy showed the effects of the BS on S. rolfsii in terms of mycelial deformations and reduced branching patterns. In vitro studies showed that the application of B. proteolyticus MITWPUB1 and its biosurfactant to seeds of Brassica juncea var local enhanced the seed germination rate. However, sawdust-carrier-based bioformulation with B. proteolyticus MITWPUB1 and its BS showed increased growth parameters for B. juncea var L. This study highlights a unique bioformulation combination that controls the growth of the phytopathogen S. rolfsii and enhances the plant growth of B. juncea var L. Bacillus proteolyticus MITWPUB1 was also shown for the first time to be a prominent BS producer with the ability to control the growth of the phytopathogen S. rolfsii.

Determining the extraction conditions and phytotoxicity threshold for compost maturity evaluation using the seed germination index method

The phytotoxicity of the compost aqueous extracts determines the maturity. To improve the accuracy of compost maturity evaluation using the seed germination index (GI) method, different extraction methods (different moisture content and extraction ratio) were designed to obtain samples with various phytotoxic level. This study analyzed the effects of different extraction condition of compost samples on GI, and established the relationship between phytotoxicity and GI. The results showed that the moisture content and extraction ratio of the compost significantly affected the GI. The extraction ratio for the compost with 60-70 % moisture content was 1:10 (ratio of compost mass to extract volume). However, commercial compost, which must have a moisture content of 30-45 %, had an extraction ratio of 1:30 (w:v). More importantly, compost extraction based on dry weight, with a moisture content of 10-15 %, more effectively reflected the phytotoxicity variations during composting. In such cases, the extraction ratio should be at least 1:30 (w:v) but not exceed 1:50 (w:v). The relationship between phytotoxicity and GI showed that dissolved organic carbon and dissolved nitrogen were the most important factors influencing GI, followed by NH4+, electrical conductivity, K, volatile fatty acids, Zn, and Cu. For composts with a GI greater than 70 %, the dissolved organic carbon, dissolved nitrogen, and NH4+ concentrations were below 257, 164, and 73 mg/L, respectively. These findings provide an optimized standard method for compost maturity evaluation using GI and a concentration threshold of key phytotoxicity is proposed to achieve accurate control of compost maturity.

Environmental implications of combustion of rice husk at high temperatures and for an extended period for energy generation

The most common alternative for the management and valorization of rice processing waste is the combustion of rice husk (RH) for energy generation. The environmental risk assessment of the ash generated during the combustion of the RH to obtain energy has remained understudied. Disposal of rice husk ash (RHA) on agricultural land is the most common outcome, which could pose a risk to both natural ecosystems and human health. The objective of this study was to characterize the physicochemical composition and the phytotoxicity, cytotoxicity, and genotoxicity of RHA obtained from three distinct combustion processes. The evaluation processes were 800-900 °C in up to 5 min (I), 800-900 °C in 15-20 min (II), and 600-700 °C in 15-20 min (III). Furthermore, the content, pH, and concentrations of Al, Cd, Cu, Fe, Mg, Mn, Mo, Na, Ni, and Ti present in the ashes were determined. The germination index for two vegetable seeds was subsequently evaluated. By measuring the mitotic index and frequency of chromosomal aberrations, the cytotoxicity and genotoxicity were determined. It was observed that RHA produced by combustion of RH at higher combustion temperatures for an extended period exhibited different physicochemical properties, in addition to higher levels of phytotoxicity, cytotoxicity, and genotoxicity.

Characterization of pumilacidin, a lipopeptide biosurfactant produced from Bacillus pumilus NITDID1 and its prospect in bioremediation of hazardous pollutants

Highly hydrophobic compounds like petroleum and their byproducts, once released into the environment, can persist indefinitely by virtue of their ability to resist microbial degradation, ultimately paving the path to severe environmental pollution. Likewise, the accumulation of toxic heavy metals like lead, cadmium, chromium, etc., in the surroundings poses an alarming threat to various living organisms. To remediate the matter in question, the applicability of a biosurfactant produced from the mangrove bacterium Bacillus pumilus NITDID1 (Accession No. KY678446.1) is reported here. The structural characterization of the produced biosurfactant revealed it to be a lipopeptide and has been identified as pumilacidin through FTIR, NMR, and MALDI-TOF MS. The critical micelle concentration of pumilacidin was 120 mg/L, and it showed a wide range of stability in surface tension reduction experiments under various environmental conditions and exhibited a high emulsification index of as much as 90%. In a simulated setup of engine oil-contaminated sand, considerable oil recovery (39.78%) by this biosurfactant was observed, and upon being added to a microbial consortium, there was an appreciable enhancement in the degradation of the used engine oil. As far as the heavy metal removal potential of biosurfactant is concerned, as much as 100% and 82% removal was observed for lead and cadmium, respectively. Thus, in a nutshell, the pumilacidin produced from Bacillus pumilus NITDID1 holds promise for multifaceted applications in the field of environmental remediation.

Modern Approaches for the Development of New Herbicides Based on Natural Compounds

Weeds are a permanent component of anthropogenic ecosystems. They require strict control to avoid the accumulation of their long-lasting seeds in the soil. With high crop infestation, many elements of crop production technologies (fertilization, productive varieties, growth stimulators, etc.) turn out to be practically meaningless due to high yield losses. Intensive use of chemical herbicides (CHs) has led to undesirable consequences: contamination of soil and wastewater, accumulation of their residues in the crop, and the emergence of CH-resistant populations of weeds. In this regard, the development of environmentally friendly CHs with new mechanisms of action is relevant. The natural phytotoxins of plant or microbial origin may be explored directly in herbicidal formulations (biorational CHs) or indirectly as scaffolds for nature-derived CHs. This review considers (1) the main current trends in the development of CHs that may be important for the enhancement of biorational herbicides; (2) the advances in the development and practical application of natural compounds for weed control; (3) the use of phytotoxins as prototypes of synthetic herbicides. Some modern approaches, such as computational methods of virtual screening and design of herbicidal molecules, development of modern formulations, and determination of molecular targets, are stressed as crucial to make the exploration of natural compounds more effective.