The Toxicity Exerted by the Antibiotic Sulfadiazine on the Growth of Soil Bacterial Communities May Increase over Time

The toxicity exerted by the antibiotic sulfadiazine on the growth of soil bacterial communities was studied in two agricultural soils for a period of 100 days. In the short-term (2 days of incubation), the effect of sulfadiazine on bacterial growth was low (no inhibition or inhibition <32% for a dose of 2000 mg·kg−1). However, sulfadiazine toxicity increased with time, achieving values of 40% inhibition, affecting bacterial growth in both soils after 100 days of incubation. These results, which were here observed for the first time for any antibiotic in soil samples, suggest that long-term experiments would be required for performing an adequate antibiotics risk assessment, as short-term experiments may underestimate toxicity effectsThis study has been funded by the Spanish Ministry of Economy and Competitiveness through the projects CGL2015-67333-C2-1-R and -2-R (FEDER Funds), and by Xunta de Galicia via CITACA Strategic Partnership (ED431E 2018/07) and BV1 research group (ED431C 2017/62-GRC). David Fernández Calviño holds a Ramón y Cajal contract (RYC-2016-20411) financed by the Spanish Ministry of Economy Industry and Competitiveness. Vanesa Santás Miguel holds a pre-doctoral fellowship founded by the University of VigoS

SARS-CoV-2 and other main pathogenic microorganisms in the environment: situation in Galicia and Spain

In the context of the current COVID-19 pandemic, and mostly taking a broad perspective, it is clearly relevant to study environmental factors that could affect eventual future outbreaks due to coronaviruses and/or other pathogenic microorganisms. In view of that, the authors of this manuscript review the situation of SARS-CoV-2 and other main pathogenic microorganisms in the environment, focusing on Galicia and Spain. Overall, in addition to showing local data, it is put in evidence that, summed to all efforts being carried out to treat/control this and any other eventual future epidemic diseases, both at local and global levels, a deep attention should be paid to ecological/environmental aspects that have effects on the planet, its ecosystems and their relations/associations with the probability of spreading of eventual future pandemicsThis work was supported by the Spanish Ministry of science, innovation and universities [grant numbers RTI2018-099574-B-C21 and RTI2018-099574-B-C22]. It also received funds from the European Regional Development Fund (ERDF) (FEDER in Spain), being a complement to the previous grants, without additional grant numberS

Sorption of antibiotics in agricultural soils as a function of pH

This study aims to understand the adsorption/desorption process in six agricultural soils of two antibiotics, Ciprofloxacin (CIP) and Trimethoprim (TRI), widely used today and the influence of pH on this process. Antibiotics can reach the soil through the application of sludge and effluents from wastewater treatment plants and are directly influenced by changes in pH, once in the soil. Therefore, this study with batch experiments allows us to know the adsorption process in a pH range between 2 and 12, in six soils with different organic carbon content, between 1% and 7.7%. The results obtained show that the adsorption of CIP has its maximum at pH between 5 and 7; above and below this range, the adsorption decreases. The soils with the highest organic carbon content (between 4.4% and 7.7%) are those with the highest adsorption. The values for each forms in which the CIP molecule is found are: for K d CIP +, between 0.887 and 8.289 L kg −1 ; for K d CIP − , between 0.670 and 5.440 L kg −1 , while for K d CIP 0 , the values do not differ from 0, except soils 1 and 3, whose values are 0.206 and 0.615 L kg −1 , respectively. Regarding TRI, the maximum adsorption takes place at acidic pHs, below 6 for all soils. Above these values, desorption decreases. The K d values for each of the species vary between 0.085 and 0.218 L kg −1 for K d TRI + , between 0.011 and 0.056 L kg −1 for K d TRI 0 , and between 0.092 and 0.189 L kg −1 for K d TRI − . For both antibiotics, the highest adsorption was achieved in the soil with the highest organic carbon content (7.7%). Comparing both antibiotics, we see that CIP presents the highest adsorption, and in the case of desorption, for CIP, it varies between 3.7% and 75.8%, with the maximum desorption at basic pHs. In the case of TRI, desorption is higher, varying between 9.4% and 99.1%, with the maximum around neutrality, except for two soils, whose maximums are at pH of 4.3 and 9.5. These results should be taken into account, as once they reach the soil, pH will be a determining factor in their behaviour and fate.Agencia Estatal de Investigación | Ref. RTI2018-099574-B-C21Agencia Estatal de Investigación | Ref. RTI2018-099574-B-C22Xunta de Galicia | Ref. ED431C2021/46-GCRXunta de Galicia | Ref. ED481B-2022-081Ministerio de Universidades | Ref. FPU19/03758Agencia Estatal de Investigación | Ref. IJC 2020-044197-

Sorption of Antibiotics in Agricultural Soils as a Function of pH

This study aims to understand the adsorption/desorption process in six agricultural soils of two antibiotics, Ciprofloxacin (CIP) and Trimethoprim (TRI), widely used today and the influence of pH on this process. Antibiotics can reach the soil through the application of sludge and effluents from wastewater treatment plants and are directly influenced by changes in pH, once in the soil. Therefore, this study with batch experiments allows us to know the adsorption process in a pH range between 2 and 12, in six soils with different organic carbon content, between 1% and 7.7%. The results obtained show that the adsorption of CIP has its maximum at pH between 5 and 7; above and below this range, the adsorption decreases. The soils with the highest organic carbon content (between 4.4% and 7.7%) are those with the highest adsorption. The values for each forms in which the CIP molecule is found are: for KdCIP+, between 0.887 and 8.289 L kg−1; for KdCIP−, between 0.670 and 5.440 L kg−1, while for KdCIP0, the values do not differ from 0, except soils 1 and 3, whose values are 0.206 and 0.615 L kg−1, respectively. Regarding TRI, the maximum adsorption takes place at acidic pHs, below 6 for all soils. Above these values, desorption decreases. The Kd values for each of the species vary between 0.085 and 0.218 L kg−1 for KdTRI+, between 0.011 and 0.056 L kg−1 for KdTRI0, and between 0.092 and 0.189 L kg−1 for KdTRI−. For both antibiotics, the highest adsorption was achieved in the soil with the highest organic carbon content (7.7%). Comparing both antibiotics, we see that CIP presents the highest adsorption, and in the case of desorption, for CIP, it varies between 3.7% and 75.8%, with the maximum desorption at basic pHs. In the case of TRI, desorption is higher, varying between 9.4% and 99.1%, with the maximum around neutrality, except for two soils, whose maximums are at pH of 4.3 and 9.5. These results should be taken into account, as once they reach the soil, pH will be a determining factor in their behaviour and fate

SARS-CoV-2 and other main pathogenic microorganisms in the environment: situation in Galicia and Spain

In the context of the current COVID-19 pandemic, and mostly taking a broad perspective, it is clearly relevant to study environmental factors that could affect eventual future outbreaks due to coronaviruses and/or other pathogenic microorganisms. In view of that, the authors of this manuscript review the situation of SARS-CoV-2 and other main pathogenic microorganisms in the environment, focusing on Galicia and Spain. Overall, in addition to showing local data, it is put in evidence that, summed to all efforts being carried out to treat/control this and any other eventual future epidemic diseases, both at local and global levels, a deep attention should be paid to ecological/environmental aspects that have effects on the planet, its ecosystems and their relations/associations with the probability of spreading of eventual future pandemics.Agencia Estatal de Investigación | Ref. RTI2018-099574-B-C21Agencia Estatal de Investigación | Ref. RTI2018-099574-B-C2

Bacterial Community Tolerance to Tetracycline Antibiotics in Cu Polluted Soils

The increase of bacterial community tolerance to Cu, and of cotolerance to the antibiotics tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC), was studied in three soils spiked with six different Cu concentrations (resulting in 0, 125, 250, 500, 750 and 1000 mg kg−1 into soils) in a laboratory experiment, after 42 days of incubation. The results show significant increases of bacterial community tolerance to the metal when soil Cu concentrations were between 125 and 500 mg kg−1. Moreover, Cu soil pollution also caused cotolerance to the three antibiotics studied but for higher Cu concentrations (1000 mg kg−1)his study has been funded by Xunta de Galicia (Consellería de Economía, Emprego e Industria) through the project ED431F 2018/06 and by the Spanish Ministry of Economy and Competitiveness through the projects CGL2015-67333-C2-1-R and -2-R (FEDER Funds). Research group was also funded by Xunta de Galicia via CITACA Strategic Partnership (ED431E 2018/07) and BV1 research group (ED431C 2017/62-GRC). David Fernández Calviño holds a Ramón y Cajal contract (RYC-2016-20411), financed by the Spanish Ministry of Economy, Industry and Competitiveness. Vanesa Santás Miguel holds a predoctoral fellowship founded by the University of VigoS

Carbon mineralization in acidic soils amended with an organo-mineral bentonite waste

Bentonite based organic-mineral wastes contains high concentrations of organic matter and plant nutrients and hence presents a high potential as a soil amendment. However, it also can have high salinity and high copper concentrations that may cause negative effects on microorganisms when the soil is amended with this type of wastes. In this work, the effect of soil amendment with a bentonite based winery waste on soil carbon mineralization was studied in acidic vineyard soils as an indicator of soil quality. The carbon mineralization in the waste is significantly lower and slower than that in the studied vineyard soils despite its significantly higher amount of organic carbon. However, when the bentonite winery waste was added to the soils, the carbon mineralization showed positive priming effects (increased between 78 and 337%). Therefore, reductions in the carbon mineralization, and hence changes on short-term organic matter turnover are not expected after bentonite waste amendment in acid soils.Xunta de Galicia | Ref. (FEADER2009-22) CO-106-0

Relevance of sorption in bio-reduction of amoxicillin taking place in forest and crop soils

The fate of antibiotics reaching soils is a matter of concern, given its potential repercussions on public health and the environment. In this work, the potential bio-reduction of the antibiotic amoxicillin (AMX), affected by sorption and desorption, is studied for 17 soils with clearly different characteristics. To carry out these studies, batch-type tests were performed, adding increasing concentrations of AMX (0, 2.5, 5, 10, 20, 30, 40, and 50 μmol L−1) to the soils. For the highest concentration added (50 μmol L−1), the adsorption values for forest soils ranged from 90.97 to 102.54 μmol kg−1 (74.21–82.41% of the amounts of antibiotic added), while the range was 69.96–94.87 μmol kg−1 (68.31–92.56%) for maize soils, and 52.72–85.40 μmol kg−1 (50.96–82.55%) for vineyard soils. When comparing the results for all soils, the highest adsorption corresponded to those more acidic and with high organic matter and non-crystalline minerals contents. The best adjustment to adsorption models corresponded to Freundlich's. AMX desorption was generally <10%; specifically, the maximum was 6.5% in forest soils, and 16.9% in agricultural soils. These results can be considered relevant since they cover agricultural and forest soils with a wide range of pH and organic matter contents, for an antibiotic that, reaching the environment as a contaminant, can pose a potential danger to human and environmental healthThis research was funded by Spanish Ministry of Science, Innovation and Universities, grant numbers RTI 2018-099574-B-C21 and RTI 2018-099574-B-C22S

Effect of biofertilizers on broccoli yield and soil quality indicators

High rates of fertilizer applications potentially have significant environmental consequences, such as soil and water contamination and biodiversity loss. This study aimed to compare the use of biofertilizers and inorganic fertilizers in a broccoli crop to determine their impact on soil microorganism abundance, microbial community structure, functional gene diversity, yield, and greenhouse gas emissions. Four different fertilization treatments were designed: (i) inorganic fertilizers applied at a rate to cover the nutritional demands of the crop (F100); (ii) 50% of the rate of inorganic fertilizers added in F100 (F50); (iii) F50 + the application of a formulation of various bacteria (BA); and (iv) F50 + the application of a formulation of bacteria and non-mycorrhizal fungi (BA + FU). The results showed that reduced fertilization and the addition of both biofertilizer products had no significant effect on soil nutrients, microbial population, microbial activity, or yield when compared to conventional inorganic fertilization. Thus, microbial inoculants were ineffective in enhancing soil microbial abundance and activity, and there were no changes in GHG emissions or crop yields. Nonetheless, crop yield was positively related to total soil N, microbial activity, and CO2 emissions, confirming the positive effect of soil biodiversity on production. The application of biofertilizers can help reduce mineral fertilization in a broccoli crop with no negative effect on yield

Correção de um solo de mina com subprodutos: efeito sobre a biomassa microbiana determinada através da utilização de ácidos gordos dos fosfolípidos

In the present work, the effect of two by-products (pine bark and crushed mussel shell) on microbial biomass and community structure was studied in a soil from a mine tailing located in a copper mine. In a laboratory experiment, different doses (0, 12, 24, 48, 96 and 192 Mg ha-1) of pine bark, crushed mussel shell or mixtures of both by-products were added to the soil. The amended soil samples were incubated for one year at 60% of water holding capacity, and then 33 phospholipid fatty acids (PLFAs) were extracted from these samples and quantified. The PLFAs concentrations were used for different microbial biomass estimations: total biomass, bacterial biomass, fungal biomass, gram-positive (G+) biomass and gram-negative (G-) biomass. The addition of crushed mussel had no significant effects on the total soil microbial biomass, either bacterial of fungal biomass. However, the addition of pine bark increased the total microbial biomass in the soil (up to 40%), mainly due to increases in the fungal biomass (it increased 1600%). No synergistic effects were observed when the soil was amended with both, pine bark and crushed mussel shell. The main community structure changes were due to the addition of pine bark to the soil, and were also due to modifications in fungal communities. Our results suggest that the microbial biomass was mainly limited in the mine soil by low organic matter concentrations, and therefore, practices increasing the amount of soil organic matter should be priorities for soil reclamation.En el presente trabajo se estudió el efecto de dos subproductos (corteza de pino y concha de mejillón triturada) sobre la biomasa y estructura microbiana de un suelo procedente de una escombrera localizada en una mina de cobre. En un experimento realizado en laboratorio fueron añadidas al suelo diferentes dosis (0, 12, 24, 48, 96 and 192 Mg ha-1) de corteza de pino, concha de mejillón triturada y mezclas de ambos subproductos. Las muestras de suelo enmendado fueron incubadas durante un año al 60% de la capacidad de campo, y posteriormente 33 ácidos grasos de los fosfolípidos (PLFAs) fueron extraídos de estas muestras y cuantificados. La concentración de PLFAs fue utilizada para realizar distintas estimaciones de la biomasa microbiana: biomasa total, biomasa bacteriana, biomasa fúngica, biomasa de bacterias gram + y biomasa de bacterias gram -. La adición de concha de mejillón triturada no tuvo efectos significativos sobre la biomasa total ni sobre la biomasa bacteriana o fúngica. Sin embargo, la adición de corteza de pino al suelo incrementó la biomasa total del suelo (hasta un 40%), debido mayormente al incremento de la biomasa fúngica (se incrementó un 1600%). Tampoco se observaron efectos sinérgicos cuando el suelo fue enmendado con una mezcla de corteza de pino y concha de mejillón triturada. Los mayores cambios en la estructura de las comunidades microbianas fueron debidos a la adición de corteza de pino al suelo, y fueron además debidas a cambios en las comunidades fúngicas. Nuestros resultados sugieren que la biomasa microbiana del suelo de mina está mayormente limitada por la concentración de materia orgánica y, por tanto, deben ser priorizadas prácticas de manejo que contribuyan a incrementarla para la rehabilitación de este tipo de suelos.Neste trabalho foi estudado o efeito de dois subprodutos (casca de pinheiro e concha de mexilhão triturada) na biomassa e estrutura microbiana de um solo procedente de uma escombreira localizada numa mina de cobre. Numa experiência de laboratório, doses diferentes (0, 12, 24, 48, 96 e 192 Mg ha-1) de casca de pinheiro, concha de mexilhão triturada e misturas de ambos os subprodutos foram adicionados ao solo. Amostras de solo corrigido com os resíduos foram incubadas durante um ano a 60% da sua capacidade de retenção de água, e subsequentemente, 33 ácidos gordos dos fosfolípidos (PLFAs) foram extraídos a partir destas amostras e quantificados. A concentração de PLFAs foi usada para estimar vários tipos de biomassa microbiana: biomassa total, biomassa bacteriana, biomassa fúngica, biomassa de bactérias gram positivas e biomassa de bactérias gram negativas. A adição de concha de mexilhão triturada não teve nenhum efeito significativo na biomassa total ou na biomassa bacteriana ou fúngica. Porém, a adição de casca de pinheiro aumentou a biomassa microbiana do solo (até 40%), principalmente devido ao aumento da biomassa fúngica (a qual aumentou de 1600%). Não foi observado nenhum efeito de sinergismo quando o solo foi corrigido com uma mistura de casca de pinheiro e concha de mexilhão triturada. As maiores alterações na estrutura das comunidades microbianas foram produzidas pela adição de casca de pinheiro ao solo, as quais resultaram em alterações nas comunidades fúngicas. Os resultados sugerem que a biomassa microbiana do solo de mina é, maioritariamente limitada pela concentração de matéria orgânica. Assim, práticas que contribuam para o seu aumento devem ser prioritárias para a reabilitação deste tipo de solos.S