A Strong Impact of Soil Tetracycline on Physiology and Biochemistry of Pea Seedlings

Allelopathic Effects of Lantana camara L. Leaf Aqueous Extracts on Germination and Seedling Growth of Capsicum annuum L. and Daucus carota L

Allelopathy is the chemical interactions between plants that might lead to either stimulation or inhibition of growth, community structure, and plant invasions. Lantana camara L. is a noxious invasive weed that negatively affects seed germination, seedling growth, and increases the mortality of the crop plant. The objective of this work was to assess allelopathic effect of L. camara leaf aqueous extract on germination and seedling growth of Capsicum annuum (pepper) and Daucus carota (carrot). The aqueous extract of Lantana leaf samples was used as a source of allelopathic effects. Data were collected for germination and seedling growth parameters. The result indicated that the highest concentration of the allelopathic extract (20 mg/L) has demonstrated significantly the highest germination inhibition rate GIR (60.00%), germination speed V (2.54 U/day) for D. carota as GIR (70.00%), mean germination time MGT (0.36 days), and GI (0.67%) for C. annuum seeds. The highest concentration of the allelopathic extract (20 mg/L) has recorded the highest plumule inhibition rate PIR (59.63%) and radical inhibition rate RIR (48.95%) for D. carota seeds, as well as PIR (27.47%) and RLR (79.49%) for C. annuum. The largest negative allelopathic index (-60.00% or allelopathic intensity of 60.00%) was recorded for D. carota seeds, whilst (-63.43% or allelopathic intensity of 63.43%) was recorded for C. annuum seed germination. For D. carota seed germination, the first principal component (PC1) has got high positive loads from GI (0.36), RLR (0.31), GR (0.34), allelopathic index AI (0.34), relative length of plumule RLP (0.24), and V (0.30). By contrast, PC1 for D. carota seed germination has got the highest negative component loads recorded by GIR (-0.34), PIR (-0.24), MGT (-0.35), and RIR (-0.31). In allelopathic effect on C. annum seed germination, the first principal component (PC1) has got high positive scores from relative length of radical RLR (0.31), RLP (0.33), germination rate GR (0.33), V (0.33), and AI (0.33). Likewise, the high negative component loads were recorded by GIR (-0.33), PIR (-0.33), RIR (-0.31), and MGT (-0.32). The result of the present study demonstrated that GIR, PIR, and RIR were directly related to negative allelopathic activity.

Intensive poultry farming: A review of the impact on the environment and human health

Poultry farming is one of the most efficient animal husbandry methods and it provides nutritional security to a significant number of the world population. Using modern intensive farming techniques, global production has reached 133.4 mil. t in 2020, with a steady growth each year. Such intensive growth methods however lead to a significant environmental footprint. Waste materials such as poultry litter and manure can pose a serious threat to environmental and human health, and need to be managed properly. Poultry production and waste by-products are linked to NH₃, N₂O and CH₄ emissions, and have an impact on global greenhouse gas emissions, as well as animal and human health. Litter and manure can contain pesticide residues, microorganisms, pathogens, pharmaceuticals (antibiotics), hormones, metals, macronutrients (at improper ratios) and other pollutants which can lead to air, soil and water contamination as well as formation of antimicrobial/multidrug resistant strains of pathogens. Dust emitted from intensive poultry production operations contains feather and skin fragments, faeces, feed particles, microorganisms and other pollutants, which can adversely impact poultry health as well as the health of farm workers and nearby inhabitants. Fastidious odours are another problem that can have an adverse impact on health and quality of life of workers and surrounding population. This study discusses the current knowledge on the impact of intensive poultry farming on environmental and human health, as well as taking a look at solutions for a sustainable future.

Physiological and Biochemical Parameters of Common Duckweed Lemna minor after the Exposure to Tetracycline and the Recovery from This Stress

In this study, the ability of Lemna minor L. to recover to normal growth, after being degraded in a tetracycline-containing medium, was extensively investigated. The plants were exposed to tetracycline (TC) at concentrations of 1, 2.5, and 10 mM. Subsequently, their physiological status was analysed against the following criteria: rate of plant growth; free radical accumulation; antioxidant enzyme activity; chlorophyll content; HSP70 protein content; cell membrane permeability, and mitochondrial activity. The study showed that duckweed can considerably recover from the damage caused by antibiotics, within a week of cessation of stress. Of the plant properties analysed, mitochondrial activity was the most sensitive to antibiotic-induced disturbances. After transferring the plants to a tetracycline-free medium, all plant parameters improved significantly, except for the mitochondrial activity in the plants grown on the medium containing the highest dose of tetracycline. In the plants treated with this antibiotic at the concentration of 10 mM, the proportion of dead mitochondria increased and was as high as 93% after one week from the beginning of the recovery phase, even after the transfer to the tetracycline-free medium.

Effects of antibiotics stress on growth variables, ultrastructure, and metabolite pattern of Brassica rapa ssp. chinensis

Antibiotics frequently contaminate agricultural fields and through plant uptake enter into the food chain. This study aimed to explore the effects of antibiotics; tetracycline (TC), oxytetracycline (OTC) and norfloxacin (NF) on the growth, cell ultrastructure, and metabolite pattern of Brassica rapa ssp. chinensis. Oxytetracycline accumulated more than other antibiotics followed by TC and NF. Plant growth, chlorophyll fluorescence, and antioxidant activities were negatively affected under all antibiotic treatments. Ultrastructural investigation of mesophyll of leaves performed by transmission electron microscopy indicated that antibiotic stress caused the changes in thylakoid orientation, number of plastoglobuli, and starch grains. Identification of functional groups through Fourier transform infrared analysis indicated that carboxyl group, carbonate and ammonium ions are involved in the adsorption of antibiotics. The metabolic profiling of B. rapa leaves demonstrated that all of the antibiotics treatments distorted phenylalanine, tyrosine and tryptophan biosynthesis, d-glutamine and d-glutamate metabolism, alanine, aspartate and glutamate metabolism, phenylalanine metabolism and TCA cycle. Metabolic alterations as a result of antibiotics stress provide insights of metabolites that affect the physiological changes attributed to antibiotic stress. These results will improve the understanding of antibiotic contamination effects on plants.

Growth responses and rubisco activity influenced by antibiotics and organic amendments used for stress alleviation in Lactuca sativa

The global increase in the consumption of antibiotics has resulted in contamination of different ecosystems with severe implications on crop productivity. This study investigated the effects of ampicillin and ofloxacin on Lactuca sativa germination upon solution exposure and growth when cultivated in soils treated with three organic amendments (compost, rice husk and vermicompost). Two levels of both antibiotics 5 and 10 mg L-1 (for solution) or mg kg-1 (for soil) were tested in addition to the control. Results indicated that addition of compost significantly (p < 0.05) increased (50%) the root lengths of plant exposed to ampicillin (5 mg L-1). Similarly, vermicompost-amended treatments displayed a 64% increase (p < 0.05) in the shoot length of seedlings under the effect of 5 mg L-1 ofloxacin, depicting a positive synergistic effect between the antibiotics and amendments in the germination test. Nevertheless, the germination percentage remained unaffected in all the treatments. In greenhouse experiment, enhanced plant biomass was observed with the use of rice husk across all the treatment groups. Comparable to the germination test, plants treated with rice husk and compost signaled a higher content of rubisco large subunit (157% and 85%, respectively) and soluble protein (248% and 108%, respectively) post antibiotics application. On the contrary, an antagonistic effect of the rice husk and ofloxacin 5 mg kg-1 was observed on the chlorophyll content, evident by a 37% decrease. Overall, it was observed that the effect of antibiotics on different plant traits vary depending on the antibiotic concentration as well as type of amendment used.

Investigation of chlorophyll degradation by tetracycline

Antibiotics represent a novel type of environment pollutants which modify chlorophyll content in plants. Spectroscopic methods were employed to investigate the effect of tetracycline on chlorophyll degradation. Changes in absorbance and fluorescence demonstrated that tetracycline reaction with chlorophyll results in the formation of pheophytin, which was confirmed by new bands typical of pheophytin which appeared in the absorbance spectrum. The rate of pheophytin formation depended on ratio tetracycline to chlorophyll concentration in solution. In solutions with chlorophyll concentration of C = 1 × 10^-5 M and tetracycline concentrations of C = 1 × 10^-3 M and C = 1 × 10^-2 M, pheophytin was formed after 28 h and 25 min, respectively. The obtained lifetime for pheophytin formed during chlorophyll reaction - with tetracycline hydrochloride was τ = 5.71 ± 0.02 ns and its value coincides, within the error limits, with the value obtained for pure pheophytin purchased from ChromaDex. The experiment demonstrated two mechanisms of chlorophyll degradation to pheophytin by tetracycline hydrochloride, i.e. 1) loss of Mg²⁺ ions from the chlorophyll molecule as a result of the presence of H⁺ ions in solution (i.e. as a result of medium acidification), and 2) removal of Mg²⁺ ions directly from chlorophyll by tetracycline which binds Mg²⁺ ions from the chlorophyll. We demonstrated that magnesium occurring in low concentrations attached to a tetracycline molecule in the BCD ring, and that the second ion of Mg2+ may attach to the A ring of tetracycline at higher Mg2+ concentrations. Two fluorescence bands appeared which indicated such magnesium attachments indeed occurred.