Allochthonous Bacteria Research Articles

Biotechnological Potential of Oil-Tolerant Strains for Possible Use in Bioremediation

The release of oil into the environment represents a pervasive problem stemming from oil exploration, accidents, transportation and releases from landfills, storage facilities or industrial plants. Compared to conventional and costly techniques, bioremediation is an attractive and promising alternative, as it can selectively degrade pollution without affecting the natural features of the site and the flora and fauna living there. In this study, the isolation, identification and characterization of autochthonous bacterial strains from a crude oil-contaminated soil sample was carried out under batch conditions over a period of 28 days. The initial colony forming units value for bacteria was 1.15 × 109/g of soil. The results show that the activity of bacteria was highest at a pH of 7.25. Based on morphology, biochemical tests and an analysis of MALDI TOF, isolated autochthonous bacterial species were identified as Bacillus megaterium, Bacillus licheniformis, Bacillus cereus and Pseudomonas chlororaphis. Since allochthonous bacteria are not highly efficient in a new environment due to their low adaptability and competition with indigenous microorganisms, these autochthonous microorganisms play a pivotal role in enhancing the bioremediation process on an applicable, industrial scale. This advancement aligns with the principles of sustainable development and the green economy, as purified soil is suitable for rational reuse in the environment.

The effectiveness of bacterial contamination of beetles during their transfer to wheat bran

The study of the mechanisms of transfer of bacteria during contamination of insect surfaces during food invasion is of current interest. Additionally, the increasing antibiotic resistance of clinical bacterial strains over the past decade has highlighted the importance of understanding the mechanisms of bacterial circulation among insects, especially antibiotic-resistant strains. Our modeling study demonstrates that the transfer of the Escherichia coli Rif (+) marker strain on the surface and inside the intestine of adult beetles Tenebrio molitor contributes to bacterial contamination of wheat bran. The isolation of E. coli Rif (+) in high titers from the beetle’s surface and feces continued for three days. The ability of beetles to carry allochthonous bacteria on their surface and inside their intestines can contribute to contamination of grains, flour, and wheat bran with antibiotic-resistant bacterial strains. In the future, the use of the Escherichia coli Rif (+) strain may help to better understand the mechanisms of how insects transfer antibiotic-resistant bacteria from one place to another during their invasion of food sources.

Huge anthropogenic microbial load during southwest monsoon season in coastal waters of Kakinada, Bay of Bengal

To examine the influence of anthropogenic activities on the marine ecosystem near the coastal waters of the port city, Kakinada, a study was conducted to investigate the abundance of heterotrophic, indicator and pathogenic bacteria during the spring inter monsoon (SIM) and southwest monsoon (SWM) seasons. A drastic change in the marine bacteria due to the input of allochthonous bacteria during SWM was noticed. An order of magnitude higher abundance of indicators (Escherichia coli and Enterococcus faecalis) and bacterial pathogens (Proteus mirabilis and Pseudomonas aeruginosa) was observed during SWM. In contrast, Chlorophyll-a, heterotrophic bacterial abundance, Aeromonas hydrophila and Klebsiella pneumoniae were higher during SIM. A significant increase in some of the indicator and pathogenic bacterial abundance due to moderate rainfall suggests that the improper drainage system in the city could spread these bacteria, posing a considerable threat to both environment and human health.

Impact of Infection with Flavobacterium psychrophilum and Antimicrobial Treatment on the Intestinal Microbiota of Rainbow Trout.

The diversity and composition of intestinal microbiota in rainbow trout have been studied using next-generation sequencing (NGS), although few studies have examined the effects of antimicrobials. We evaluated the effect of antibiotics florfenicol and erythromycin and infection with or without Flavobacterium psychrophilum on the intestinal microbiota in rainbow trout juveniles (30-40 g) using NGS. Prophylactic oral antibiotic treatments were administered for 10 days before groups of fish were injected intraperitoneally with virulent F. psychrophilum. Intestinal content (allochthonous bacteria) was collected at day -11, 0, 12, and 24 p.i., and the v3-v4 region of the 16S rRNA gene was sequenced using Illumina MiSeq. Before prophylactic treatment, Tenericutes and Proteobacteria were the most abundant phyla identified and Mycoplasma was the most abundant genus. Fish infected with F. psychrophilum had decreased alpha diversity and a high abundance of Mycoplasma. Fish administered florfenicol had increased alpha diversity compared to the control at day 24 p.i., although both florfenicol and erythromycin-treated fish had a higher abundance of potential pathogens, specifically Aeromonas, Pseudomonas, and Acinetobacter. Mycoplasma disappeared after treatment but appeared again after day 24. This study demonstrates that prophylactic oral treatment with antibiotics florfenicol and erythromycin as well as F. psychrophilum infection changed the composition of intestinal microbiota in rainbow trout juveniles that did not recover by day 24 p.i. and further long-term effects on the host need to be investigated.

Response of Soil Microbial Community (Bacteria and Fungi) to Organic and Inorganic Amendments Using Tomato as a Test Crop

A field experiment was conducted to evaluate the response of soil microorganisms (bacteria and fungi), to some soil amendments (organic and inorganic) at site A and site B. The experiments were laid out in a randomized complete block design (RCBD). The treatments applied were compost (3.4 t/ha), poultry manure (4.2 t/ha), Tithonia diversifolia (4.8 t/ha), NPK (15:15:15) (0.8 t/ha) at 120 kg N/ha, and the control. Treatments were replicated three times. Tomato seedlings were raised in the nursery and transplanted to the field after 3 weeks with a spacing of 50 × 50 cm. Soil microbiomes (Fungi and Bacteria) were isolated using the serial dilution technique. Compost improved both the total number of fungi by 12%–178% and diversity by 1.09%–85% compared to the other amendments at both sites, while the diversity of bacteria was increased more by Tithonia diversifolia (11%–75%). The total number of bacteria was highest in plots amended with compost at site A. Compost had the highest percentage of bacteria suppressed compared to other amendments studied at both sites (27.3% and 28.5%, respectively). NPK had the highest bacteria suppression at site A. The plot amended with NPK had the highest percentage of bacteria enhanced at site A. NPK had the highest at site B. Poultry had the highest reduction in bacteria at site A. Tithonia diversifolia had the highest percentage proliferation of allochthonous bacteria at both sites with 23.7% and 27.7%, respectively, while compost plots had the least allochthonous bacteria at both sites. At both sites, the percentage of suppressed fungi was highest in plots amended with poultry manure and control. Compost and T. diversifolia had the highest percentage of fungus growth reduction in site A (26.3%). At site A, compost had the highest percentage of allochthonous fungi (29%). Application of compost, poultry manure, and Tithonia diversifolia is recommended for the improvement of soil microbial properties.

Antimicrobial impacts of selected Lamiaceae plants on bacteria isolated from vegetables and their application in edible films

Fresh vegetables can be contaminated with spoilage and food-borne pathogenic bacteria during cultivation, harvesting, transport and further processing. The essential oils seem a promising solution for preserving vegetables incorporated in edible films. During the study it was determined the prevalence of allochthonous bacteria on some fresh vegetables with classical cultivation and molecular biology techniques. The evaluation of the antibacterial effect of Thymus vulgaris, Origanum vulgare, Mentha piperita and Melissa officinalis essential oils against identified bacteria from vegetables and on some standard foodborne pathogenic bacteria was realized with agar diffusion method.The prevalence of allochthonous bacteria in the examined vegetables was diverse. In some cases, high contamination level could be detected reaching the level of 10 4 colony forming units/g. The identified bacteria belong to different genera like Bacillus, Enterobacter, Pseudomonas etc. Of the tested plant essential oils, the most pronounced antibacterial effect was detected in the case of thyme and oregano, with over 30 mm inhibition zone. The isolated bacteria from vegetables showed higher resistance to the used essential oils.The results suggest that edible films containing thyme and oregano essential oils possess efficient antibacterial effect against mesophilic aerobic bacteria and Staphylococcus aureus. These findings seem a promising solution for preserving vegetables with natural antimicrobial containing edible films.

Autochthonous and allochthonous lactic acid bacteria: action on the hematological and intestinal microbiota for two species of Astyanax genus.

The objective of this work was to evaluate the effect of autochthonous and allochthonous lactic acid bacteria (LAB) in two species of lambaris (Astyanax bimaculatus and Astyanax fasciatus), and to investigate the effects on intestinal microbiota and hematological changes. Two experiments were carried out, one for each lambari species, both assays were divided into three treatments: autochthonous LAB, allochthonous LAB and control. The 10% inoculum was included on diet in the LAB treatments and sterile medium for control. After 30 days for A. bimaculatus LAB indigenous changes all bacteria groups analyzed, while allochthonous LAB just decrease Staphylococcus spp. count. Though for A. fasciatus his autochthone LAB reduced the staphylococcal count. In hematology, for A. bimaculatus autochthonous LAB showed a higher number of thrombocytes, lymphocytes, monocytes and total leukocytes in the circulatory system than the control. Though for A. fasciatus his autochthone LAB showed a higher number of total lymphocytes and leukocytes than the control, while Lactobacillus sp. acting as an allochthone, it did not differ among treatments. In conclusion, both LAB (Lactobacillus sp. and L. lactis) promoted more beneficial changes in the microbiota and hematological profile when they act as an autochthone probiotic, demonstrating a probiotic-associated host.

Hydrodynamic‐Driven Changes in the Source and Composition of Sedimentary Organic Matter via Grain Size Distribution in Shallow Lakes

AbstractSediment organic matter (SOM) differs in composition and function in different size fractions in relation to material and energy flows. The hydrodynamic effects on a lake's autochthonous (terrestrial plants) and allochthonous (microalgae, aquatic plants, and bacteria) inputs and transformation, and the components of SOM are still far from clear. To elucidate the SOM composition as driven by the hydrodynamic conditions associated with sedimentary grain size, we performed an ecosystem‐level investigation in the shallow lake Izunuma, Japan, measuring source‐specific fatty acids and the current velocity. High organic matter concentrations occurred in the finer fractions. Bacteria were dominant in the <32 μm fraction, microalgae were mainly present in the <32 and 63–125 μm fractions, aquatic plants appeared to be evenly distributed in all size fractions, and terrestrial plants mainly comprised the >125 μm fraction. Although the linear correlation between current velocity and sedimentary total organic carbon (TOC) was not statistically significant, the relationship between current velocity frequency and sedimentary TOC was significant. The highest Pearson coefficient occurred at a current velocity of 6 cm/s in sand. The relationship between allochthonous inputs and current velocity frequency was similar to that of TOC. Autochthonous organics had the greatest coefficient with two peaks at 4.5 and 8 cm/s. The threshold for sand resuspension varied with organic sources, while this phenomenon was absent in cohesive mud. Hydrodynamic forces affected the grain size of sediments and drove the gradient distribution of the SOM sources, which should be considered when managing freshwater lakes in light of future climate change.

Preliminary insights about the treatment of contaminated marine sediments by means of bioslurry reactor: Process evaluation and microbiological characterization

Contaminated marine sediments represent a critical threat towards human health and ecosystems, since they constitute a potential reservoir of toxic compounds release. In the present study, a bioslurry reactor was studied for the treatment of real marine sediments contaminated by petroleum hydrocarbons. The experimental campaign was divided in two periods: in the first period, microcosm trials were carried out to achieve useful indicators for biological hydrocarbon removal from sediments. The microcosm trials highlighted that the inoculum of halotolerant allochthonous bacteria provided the highest performance followed by autochthonous biomass. Based on the achieved results, in the second experimental period a bioslurry reactor was started up, based on a semisolid stirred tank reactor (STR) operated in batch mode. The process performances have been evaluated in terms of total petroleum hydrocarbon (TPH) removal, coupled with the characterization of microbial community through a Next Generation Sequencing (NGS) and phytotoxicity tests through the Germination Index (GI) with Lepidium Sativum seeds. The achieved results showed good hydrocarbons removal, equal to 40%, with a maximum removal rate of 220 mgTPH kg-1 d-1, but highlighting that high contaminant concentrations might affect negatively the overall removal performance. In general, the observed results were encouraging towards the feasibility of biological treatment of marine sediments contaminated by hydrocarbons. The microbiological analysis allowed the identification of taxa most involved in the degradation of TPH, highlighting after the treatment a shift in the microbial community from that of the raw sediment.

Antibiotic resistance pattern of the allochthonous bacteria isolated from commercially available spices.

Spices are often used in dried form, sometimes with significant microbial contamination including pathogenic and food spoilage bacteria. The antibiotic resistance represents an additional risk for food industry, and it is worthy of special attention as spices are important food additives. During our work, we examined the microbiological quality of 50 different spices with cultivation methods on diverse selective media. The identification of the most representative bacteria was carried out using 16S rDNA gene sequence analysis. Antibiotic resistance profiling of twelve identified Bacillus species (B. subtilis subsp. stercoris BCFK, B. licheniformis BCLS, B. siamensis SZBC, B. zhangzhouensis BCTA, B. altitudinis SALKÖ, B. velezensis CVBC, B. cereus SALÖB isolate, B. tequilensis KOPS, B. filamentosus BMBC, B. subtilis subsp. subtilis PRBC2, B. safensis BMPS, and B. mojavensis BCFK2 isolate) was performed using the standard disk‐diffusion method against 32 antibiotics. The study showed that the majority resistance was obtained against penicillin G (100%), oxacillin (91.67%), amoxyclav (91.67%), rifampicin (75%), and azithromycin (75%). Our findings suggest that spices harbor multidrug‐resistant bacteria.

Effect of Water Chemistry, Land Use Patterns, and Geographic Distances on the Spatial Distribution of Bacterioplankton Communities in an Anthropogenically Disturbed Riverine Ecosystem.

The spatial distribution of bacterioplankton communities in rivers is driven by multiple environmental factors, including local and regional factors. Local environmental condition is associated with effect of river water chemistry (through species sorting); ecological process in region is associated with effects of land use and geography. Here, we investigated variation in bacterioplankton communities (free-living, between 0.22 and 5 μm) in an anthropogenically disturbed river using high-throughput DNA sequencing of community 16S rRNA genes in order to investigate the importance of water chemistry, land use patterns, and geographic distance. Among environmental factors, sulfate (SO42–), manganese (Mn), and iron (Fe) concentrations were the water chemistry parameters that best explained bacterioplankton community variation. In addition, forest and freshwater areas were the land use patterns that best explained bacterioplankton community variation. Furthermore, cumulative dendritic distance was the geographic distance parameter that best explained bacterial community variation. Variation partitioning analysis revealed that water chemistry, land use patterns, and geographic distances strongly shaped bacterioplankton communities. In particular, the direct influence of land use was prominent, which alone contributed to the highest proportion of variation (26.2% in wet season communities and 36.5% in dry season communities). These results suggest that the mechanisms of species sorting and mass effects together control bacterioplankton communities, although mass effects exhibited higher contributions to community variation than species sorting. Given the importance of allochthonous bacteria input from various land use activities (i.e., mass effects), these results provide new insights into the environmental factors and determinant mechanisms that shape riverine ecosystem communities.

Allochthonous and Autochthonous Halothermotolerant Bioanodes From Hypersaline Sediment and Textile Wastewater: A Promising Microbial Electrochemical Process for Energy Recovery Coupled With Real Textile Wastewater Treatment.

The textile and clothing industry is the first manufacture sector in Tunisia in terms of employment and number of enterprises. It generates large volumes of textile dyeing wastewater (TDWW) containing high concentrations of saline, alkaline, and recalcitrant pollutants that could fuel tenacious and resilient electrochemically active microorganisms in bioanodes of bioelectrochemical systems. In this study, a designed hybrid bacterial halothermotolerant bioanode incorporating indigenous and exogenous bacteria from both hypersaline sediment of Chott El Djerid (HSCE) and TDWW is proposed for simultaneous treatment of real TDWW and anodic current generation under high salinity. For the proposed halothermotolerant bioanodes, electrical current production, chemical oxygen demand (COD) removal efficiency, and bacterial community dynamics were monitored. All the experiments of halothermotolerant bioanode formation have been conducted on 6 cm2 carbon felt electrodes polarized at −0.1 V/SCE and inoculated with 80% of TDWW and 20% of HSCE for 17 days at 45°C. A reproducible current production of about 12.5 ± 0.2 A/m2 and a total of 91 ± 3% of COD removal efficiency were experimentally validated. Metagenomic analysis demonstrated significant differences in bacterial diversity mainly at species level between anodic biofilms incorporating allochthonous and autochthonous bacteria and anodic biofilm containing only autochthonous bacteria as a control. Therefore, we concluded that these results provide for the first time a new noteworthy alternative for achieving treatment and recover energy, in the form of a high electric current, from real saline TDWW.

Fruits and fruit by-products as sources of bioactive compounds. Benefits and trends of lactic acid fermentation in the development of novel fruit-based functional beverages

Current awareness about the benefits of a balanced diet supports ongoing trends in humans towards a healthier diet. This review provides an overview of fruits and fruit-by products as sources of bioactive compounds and their extraction techniques, and the use of lactic acid fermentation of fruit juices to increase their functionality. Fruit matrices emerge as a technological alternative to be fermented by autochthonous or allochthonous lactic acid bacteria (LAB such as Lactiplantibacillus plantarum, Lacticaseibacillus rhamnosus, and other Lactobacillus species), and also as probiotic vehicles. During fermentation, microbial enzymes act on several fruit phytochemicals producing new derived compounds with impact on the aroma and the functionality of the fermented drinks. Moreover, fermentation significantly reduces the sugar content improving their nutritional value and extending the shelf-life of fruit-based beverages. The generation of new probiotic beverages as alternatives to consumers with intolerance to lactose or with vegan or vegetarian diets is promising for the worldwide functional food market. An updated overview on the current knowledge of the use of fruit matrices to be fermented by LAB and the interaction between strains and the fruit phytochemical compounds to generate new functional foods as well as their future perspectives in association with the application of nanotechnology techniques are presented in this review.

Assessment of dietary supplementation with galactomannan oligosaccharides and phytogenics on gut microbiota of European sea bass (Dicentrarchus Labrax) fed low fishmeal and fish oil based diet.

There is an increasing interest from the aquafeed industry in functional feeds containing selected additives that improve fish growth performance and health status. Functional feed additives include probiotics, prebiotics, organic acids, and phytogenics (substances derived from plants and their extracts). This study evaluated the effects of dietary inclusion of a mucilage extract rich in galactomannan oligosaccharides (GMOS), a mixture of garlic and labiatae-plants oils (PHYTO), and a combination of them (GMOSPHYTO), on gut microbiota composition of European sea bass (Dicentrarchus labrax) fed with a low fishmeal (FM) and fish oil (FO) diet. Three experimental diets and a control diet (plant-based formulation with 10% FM and 6% FO) were tested in a 63-days feeding trial. To analyze the microbiota associated to feeds and the intestinal autochthonous (mucosa-adhered) and allochthonous (transient) microbial communities, the Illumina MiSeq platform for sequencing of 16S rRNA gene and QIIME2 pipeline were used. Metabarcoding analysis of feed-associated bacteria showed that the microbial communities of control (CTRL) feed deeply differed from those of experimental diets. The number of reads was significantly lower in CTRL feed than in other feeds. The OTU (operational taxonomic unit) number was instead similar between the feeds, ranging from 42 to 50 OTUs. The variation of resident gut microbiota induced by diet was lower than the variation of transient intestinal microbiota, because feedstuffs are a major source of allochthonous bacteria, which can temporarily integrate into the gut transient microbiome. However, the composition of transient bacterial communities was not simply a mirror of feed-borne bacteria. Indeed, the microbial profile of feeds was different from both faecal and mucosa profiles. Our findings suggest that the dietary inclusion of GMOS (0.5%) and PHYTO (0.02%) in a low FM and FO diet induces changes in gut microbiota composition of European sea bass. However, if on allochthonous microbiota the combined inclusion of GMOS and PHYTO showed an antagonistic effect on bactericidal activity against Vibrionales, at mucosa level, only GMOSPHYTO diet increased the relative abundance of Bacteroidales, Lactobacillales, and Clostridiales resident bacterial orders. The main beneficial effects of GMOS and PHYTO on gut microbiota are the reduction of coliforms and Vibrionales bacteria, which include several potentially pathogenic species for fish, and the enrichment of gut microbiota composition with butyrate producer taxa. Therefore, these functional ingredients have a great potential to be used as health-promoting agents in the farming of European sea bass and other marine fish.

Resistome, Mobilome and Virulome Analysis of Shewanella algae and Vibrio spp. Strains Isolated in Italian Aquaculture Centers.

Antimicrobial resistance is a major public health concern restricted not only to healthcare settings but also to veterinary and environmental ones. In this study, we analyzed, by whole genome sequencing (WGS) the resistome, mobilome and virulome of 12 multidrug-resistant (MDR) marine strains belonging to Shewanellaceae and Vibrionaceae families collected at aquaculture centers in Italy. The results evidenced the presence of several resistance mechanisms including enzyme and efflux pump systems conferring resistance to beta-lactams, quinolones, tetracyclines, macrolides, polymyxins, chloramphenicol, fosfomycin, erythromycin, detergents and heavy metals. Mobilome analysis did not find circular elements but class I integrons, integrative and conjugative element (ICE) associated modules, prophages and different insertion sequence (IS) family transposases. These mobile genetic elements (MGEs) are usually present in other aquatic bacteria but also in Enterobacteriaceae suggesting their transferability among autochthonous and allochthonous bacteria of the resilient microbiota. Regarding the presence of virulence factors, hemolytic activity was detected both in the Shewanella algae and in Vibrio spp. strains. To conclude, these data indicate the role as a reservoir of resistance and virulence genes in the environment of the aquatic microbiota present in the examined Italian fish farms that potentially might be transferred to bacteria of medical interest.

The vertical distribution of tetA and intI1 in a deep lake is rather due to sedimentation than to resuspension.

Lakes are exposed to anthropogenic pollution including the release of allochthonous bacteria into their waters. Antibiotic resistance genes (ARGs) stabilize in bacterial communities of temperate lakes, and these environments act as long-term reservoirs of ARGs. Still, it is not clear if the stabilization of the ARGs is caused by a periodical introduction, or by other factors regulated by dynamics within the water column. Here we observed the dynamics of the tetracycline resistance gene (tetA) and of the class 1 integron integrase gene intI1 a proxy of anthropogenic pollution in the water column and in the sediments of subalpine Lake Maggiore, together with several chemical, physical and microbiological variables. Both genes resulted more abundant within the bacterial community of the sediment compared to the water column and the water-sediment interface. Only at the inset of thermal stratification they reached quantifiable abundances in all the water layers, too. Moreover, the bacterial communities of the water-sediment interface were more similar to deep waters than to the sediments. These results suggest that the vertical distribution of tetA and intI1 is mainly due to the deposition of bacteria from the surface water to the sediment, while their resuspension from the sediment is less important.

EFFECTS OF HIGH URACIL DIET-INDUCED GUT DYSBIOSIS ON COURTSHIP BEHAVIOR IN DROSOPHILA

AbstractPast research has established that Drosophila gut inflammation via the dual oxidase (DUOX) regulatory pathway is induced by exposure to bacterial-derived uracil, which can be secreted by allochthonous and autochthonous bacteria in the midgut. However, the effects of the inflammatory response and resulting gut dysbiosis on the courtship behavior of the Drosophila host have yet to be determined. This work studies the changes in Drosophila courtship behavior resulting from diet-based exposure to uracil, a ligand for DUOX-dependent reactive oxygen species (ROS) generation in the epithelia of the midgut. The effects of a high-uracil diet on courtship behavior were determined by comparing courtship index (CI) values of flies treated with 20 nM of uracil for 16-hr (short-term) or 10-d (long-term) exposure to age-matched control flies. Although short-term uracil treatment caused no change in courtship behavior, long-term uracil treatment resulted in a significant decrease in CI. This result suggests that the underlying association for the behavioral change may be influenced by gut inflammation initiated by long-term exposure to uracil. By measuring the effects of an innate immune response such as exposure to a ligand for DUOX-dependent ROS generation on the courtship index of Drosophila, the current understanding of the relationship between gut inflammation and behavioral changes in animals can be expanded. Given that prior research has also established that the DUOX-dependent response can be found in animals ranging from Drosophila to humans, the behavioral changes observed from induction of the pathway have the potential to expand this connection in the future.

The Impact of a Fish Cannery Wastewater Discharge on the Bacterial Community Structure and Sanitary Conditions of Marine Coastal Sediments

The effects of fish cannery discharge (FCD) on bacteria in marine coastal sediments were investigated. Redox potentials were measured, and granulometry was determined by wet ASTM sieving, and with the Sedigraph method. Prokaryotic abundance (PA) was determined by epifluorescence microscopy (DAPI staining), and faecal indicator bacteria (FIB) enumerated with the multiple test tube and most probable number method. Total lipids were determined gravimetrically, and sterols analysed by GC/MSD. Bacterial community composition was determined after total DNA isolation, Illumina MiSeq amplification, and SILVAngs processing pipeline. The FCD was rich in lipids, heterotrophic prokaryotes and FIB. The bacterial community of the FCD was dominated by Firmicutes and Gammaproteobacteria and many potentially pathogenic bacteria. Highly porosusgravelly sands clogged with fish remains transitioned to less permeable sandy muds away from the FCD. All sediments were anoxic with extremely negative potentials around the outfall. High surface PA and FIB spread 300 m from the outfall. Gammaproteobacteria and Deltaproteobacteria appeared in all sediments. Sulfurovum and Anaerolineaceae characterized the most polluted locations where gammaproteobacterial Woeseiaceae/JTB255 marine benthic group declined. Gammaproteobacteria and Bacteroidetes characterized surface sediments, while Chloroflexi and Deltaproteobacteria prevailed in deeper layers. The FCD enriched sediments in lipids and allochthonous bacteria degrading sanitary quality, lowering the permeability, redox potential, and bacterial diversity.

Seasonality of the antibiotic resistance gene blaCTX-M in temperate Lake Maggiore

The beta lactamase gene blaCTX-M, responsible of the resistance to cephalosporins, has been detected in microbes from hospitals to open waters. We studied the seasonality and stability of blaCTX-M in Lake Maggiore over 3 years and the role of potential inputs of allochthonous bacteria and/or antibiotic pollution in promoting its occurrence. blaCTX-M was mainly present from January to July in the pelagic microbial community and the gene occurrence was significantly related to low water temperature. To evaluate its temporal stability in the bacterial community over a short period, we measured blaCTX-M daily over the course of 6 days. The gene was below the limit of quantification except for one sampling when its abundance peaked, suggesting a point contamination. The bacterial community of the lake in which blaCTX-M was detected suggests that at least two distinct bacterial populations contained the gene. The occurrence of known blaCTX-M containing genera and the occurrence of the gene, however, did not overlap. Furthermore, the experimental addition of cefotaxime to lake water incubations did not promote abundance of the gene. These data imply that blaCTX-M was present in the environmental microbial community. Increases of gene abundances were likely caused by environmental parameters other than antibiotic contamination.

Cultivation of a versatile manganese-oxidizing aerobic granular sludge for removal of organic micropollutants from wastewater

Organic micropollutants (OMPs) are frequently detected in water and wastewater, and have attracted wide attention due to potential adverse effects on ecosystems and human health. In this work, manganese-oxidizing aerobic granular sludge (Mn-AGS) was successfully cultivated and applied to remove OMPs from wastewater. Biogenic manganese (III,IV) oxides (bio-MnOx) were generated and accumulated to 22.0–28.3 mg Mn/g SS in the final sludge. Neither the addition of allochthonous manganese-oxidizing bacteria (MnOB; Pseudomonas putida MnB1) nor the reduction in hydraulic retention time (HRT) facilitated the cultivation of Mn-AGS. Batch experiments of OMPs degradation indicated that Mn-AGS significantly improved (1.3–3.9 times) degradation rates of most OMPs. Removal rates of bisphenol A (BPA), 17α‑ethinylestradiol (EE2), tetracycline (TC), and chloramphenicol (CAP) were 3.0–12.6 μg/h/g SS by the traditional AGS and 8.0–16.3 μg/h/g SS by Mn-AGS; those of imazethapyr (IM) were relatively high, 64.7 ± 0.1 and 127.8 ± 2.5 μg/h/g SS by AGS and Mn-AGS, respectively. However, degradation of dichlorophenyl phosphine (DCPP) was slower by Mn-AGS than AGS, 9.0 ± 0.4 vs. 21.2 ± 0.9 μg/h/g SS, possibly due to inhibition of microbial activity by bio-MnOx. This work provides a promising method for treating OMPs in organic wastewater, but the possible inhibition of microbes by bio-MnOx should be noted.