Major Source Of Nutrients Research Articles

Beach wrack as a potential microplastic hot spot in the South-Eastern Baltic Sea environment

Beach wrack is considered as a major source of nutrients to the sandy coast ecosystems in the South-East Baltic Sea, and it serves as the natural beach sediment storage and habitat formation material. However, it also could be a hot spot for microplastic and other types of marine litter accumulation. We carried out the recovery rate experiments to determine the most reliable method for a rapid and cost-effective application to extract microplastics from the beach wrack. The aeration of media in a saturated solution of sodium chloride revealed to be statistically significant and reliable, therefore was selected as a most suitable to extract the microplastics from the beach wrack. This study shows that the concentration of microplastics is significantly different between the four analyzed compartments in the coastal zone. The microplastic concentration in a beach wrack, with a mean value of 0.47 ± 0.17 items/cm3, contained 4.7 times more microplastics than observed in the surface sand samples. This study estimated that on average over 450 million microplastic items could be found during the castaway event in the South-East Baltic Sea coast.

Development and evaluation of a web-based diet quality screener for vegans (VEGANScreener): a cross-sectional, observational, multicenter, clinical study.

Consumption of plant-based diets, including vegan diets, necessitates attention to the quality of the diet for the prevention and early detection of nutritional deficiencies. Within the VEGANScreener project, a unique brief screening tool for the assessment and monitoring of diet quality among vegans in Europe was developed. To provide a standardized tool for public use, a clinical study will be conducted to evaluate the VEGANScreener against a reference dietary assessment method and nutritional biomarkers. An observational study is set to include 600 participants across five European sites - Belgium, Czech Republic, Germany, Spain, and Switzerland. In total, 400 self-reported vegans (≥2 years on a vegan diet), and 170 self-reported omnivore controls will be examined, aged between 18 and 65 years, with males and females being equally represented in a 1:1 ratio for two age groups (18-35 and 36-65 years). Participants with diseases affecting metabolism and intestinal integrity will be excluded. The clinical assessment will include a structured medical history, along with taking blood pressure and anthropometric measurements. Blood and urine will be sampled and analyzed for a set of dietary biomarkers. Metabolomic analyses will be conducted to explore potential novel biomarkers of vegan diet. Moreover, saliva samples will be collected to assess the metabolome and the microbiome. Participants will receive instructions to complete a nonconsecutive 4-day diet record, along with the VEGANScreener, a socio-demographic survey, a well-being survey, and a FFQ. To evaluate reproducibility, the VEGANScreener will be administered twice over a three-weeks period. Among vegans, the construct validity and criterion validity of the VEGANScreener will be analyzed through associations of the score with nutrient and food group intakes, diet quality scores assessed from the 4-day diet records, and associations with the dietary biomarkers. Secondary outcomes will include analysis of dietary data, metabolomics, and microbiomes in all participants. Major nutrient sources and variations will be assessed in the sample. Exploratory metabolomic analysis will be performed using multivariable statistics and regression analysis to identify novel biomarkers. Standard statistical models will be implemented for cross-sectional comparisons of geographical groups and vegans versus omnivores.

Reducing wastewater nitrogen loading by >90% with carbon-amended septic systems: A field demonstration in Barnstable (Cape Cod), Massachusetts

Onsite wastewater treatment systems (OWTS) are a major source of excess nutrients and co-pollutants in watersheds across the United States. In Barnstable County (Cape Cod), Massachusetts, effluent from septic systems and cesspools contributes approximately 80% of the controllable reactive nitrogen (N) load to numerous impaired estuaries and degrades water quality in the region's sole source aquifer, streams and ponds. In unsewered areas, wastewater N loads could be reduced substantially by Innovative/Alternative (I/A) septic systems designed for enhanced removal. Use, however, has been partly limited by the availability of high performing, cost effective options, while conventional septic systems continue to be installed in watersheds with well documented N impairments. This paper describes the strategic replacement of residential OWTS with two I/A models that incorporate woodchip bioreactors to enhance N removal. Systems were installed at 14 neighboring homes in Barnstable, MA, and monitored for field performance. Influent and effluent were sampled monthly and analyzed for N and phosphorus (P), among other water quality indicators. Flow to each system was continuously metered to estimate nutrient loads. Results from the first 25 months of monitoring for 13 systems with at least a full year of data are presented in terms of 1) reductions in nutrient concentrations and mass loads and 2) reliability of the systems for meeting a performance goal of total N (TN) < 10 mg/L. Discussion supports consideration of where and how these technologies may be successfully used to manage excess N in sensitive watersheds.

Exploring the contribution of the salivary gland and midgut to digestion in the swede midge (Contarinia nasturtii) through a genomics-guided approach.

The larvae of Contarinia nasturtii (Kieffer) (Diptera: Cecidomyiidae), the swede midge, targets the meristem of brassica crops where they induce the formation of galls and disrupt seed and vegetable production. Previously, we examined the salivary gland transcriptome of newly-hatched first instar larvae as they penetrated the host and initiated gall formation. Here we examine the salivary gland and midgut transcriptome of third instar larvae and provide evidence for cooperative nutrient acquisition beginning with secretion of enzymes and feeding facilitators followed by gastrointestinal digestion. Sucrose, presumably obtained from the phloem, appeared to be a major nutrient source as several α-glucosidases (sucrases, maltases) and β-fructofuranosidases (invertases) were identified. Genes encoding β-fructofuranosidases/invertases were among the most highly expressed in both tissues and represented two distinct gene families that may have originated via horizontal gene transfer from bacteria. The importance of the phloem as a nutrient source is underscored by the expression of genes encoding regucalcin and ARMET (arginine-rich mutated in early stages of tumor) which interfere with calcium signalling and prevent sieve tube occlusion. Lipids, proteins, and starch appear to serve as a secondary nutrient sources. Genes encoding enzymes involved in the detoxification of glucosinolates (myrosinases, arylsulfatases, and glutathione-S-transferases) were expressed indicative of Brassicaceae host specialization. The midgut expressed simple peritrophins and mucins typical of those found in Type II peritrophic matrices, the first such description for a gall midge.

Biomass, productivity and monetary efficiency of various cropping systems in the Almora district of the Indian Himalaya

ABSTRACT Uttarakhand hills are blessed with mesmerizing beauty but low crop productivity because of which the farmers are diverting from agriculture. A research investigation was conducted in Dantola village, Almora District, Uttarakhand, India, to understand the dynamics and performance of hill agro-ecosystems by estimating biomass, productivity and monetary efficiency of the existing cropping systems. Total five systems were selected which consist of six monocrops, three mixed crops, two agri-silviculture systems, one agri-horticulture system and silvi-hortipasture system. System-wise, higher biomass was observed in agri-silviculture system with an average value of 134.3 tonnes/ha. Farmyard manure was found to be the major source of nutrients supply to the crops. The monetary efficiency of various cropping systems revealed that the total returns were highest in the agri-horticulture system (USD 8805.76/ha) followed by horsegram+sorghum (USD 1620.49/ha) and urdbean (USD 1448.65/ha). When the net benefit from various cropping systems was analysed, maximum net returns were observed in agri-horticulture (USD 5867.57 lakh/ha), followed by horsegram+sorghum (mixed cropping) and urdbean. Overall, agri-silviculture systems provided higher biomass while legumes, agri-horticulture system and silvi-hortipasture systems were found to be the most efficient in terms of production and monetary efficiency and therefore can be recommended to the farming communities.

On the association between dietary oily fish intake and bone mineral density in frequent fish consumers of Amerindian ancestry. The three villages study.

Oily fish is a major dietary source of omega-3 polyunsaturated fatty acids and other nutrients that may have a positive effect on bone health. However, this association is inconsistent and seems to be more evident in certain ethnic groups. We aimed to assess the association between oily fish intake and bone mineral density (BMD) in frequent fish consumers of Amerindian ancestry living in rural Ecuador. This study included 399 individuals aged ≥ 60years living in three neighboring rural villages of coastal Ecuador. Dietary oily fish intake was quantified systematically using validated surveys and BMD was determined by dual-energy x-ray absorptiometry. Ordinal logistic regression models, adjusted for demographics and cardiovascular risk factors, were fitted to assess the independent association between oily fish intake and bone health. Participants had a mean age of 68.8 ± 6.8years, and 58% were women. The mean intake of oily fish was 8.5 ± 4.7 servings/week, with 308 (77%) reporting high fish intake (≥ 5.2 servings/week [728g]). Ninety-four (24%) participants had normal BMD T-scores, 149 (37%) had osteopenia, and 156 (39%) had osteoporosis. Ordinal logistic regression models showed no association between high fish intake and bone health in the total population. When men and women were analyzed separately, the association became significant for women only in both unadjusted (OR: 2.52; 95% C.I.: 1.22 - 5.23) and fully-adjusted models (OR: 2.23; 95% C.I.: 1.03 - 4.81). Consumption of ≥ 5.2 oily fish servings/week is associated with lower prevalence of osteopenia and osteoporosis in elderly women of Amerindian ancestry.

Environmental DNA highlights the influence of salinity and agricultural run-off on coastal fish assemblages in the Great Barrier Reef region

Agricultural run-off in Australia's Mackay-Whitsunday region is a major source of nutrient and pesticide pollution to coastal and inshore ecosystems of the Great Barrier Reef. While the effects of run-off are well documented for the region's coral and seagrass habitats, the ecological impacts on estuaries, the direct recipients of run-off, are less known. This is particularly true for fish communities, which are shaped by the physico-chemical properties of coastal waterways that vary greatly in tropical regions. To address this knowledge gap, we used environmental DNA (eDNA) metabarcoding to examine fish assemblages at four locations (three estuaries and a harbour) subjected to varying levels of agricultural run-off during a wet and dry season. Pesticide and nutrient concentrations were markedly elevated during the sampled wet season with the influx of freshwater and agricultural run-off. Fish taxa richness significantly decreased in all three estuaries (F = 164.73, P = <0.001), along with pronounced changes in community composition (F = 46.68, P = 0.001) associated with environmental variables (largely salinity: 27.48% contribution to total variance). In contrast, the nearby Mackay Harbour exhibited a far more stable community structure, with no marked changes in fish assemblages observed between the sampled seasons. Among the four sampled locations, variation in fish community composition was more pronounced within the wet season (F = 2.5, P = 0.001). Notably, variation in the wet season was significantly correlated with agricultural contaminants (phosphorus: 6.25%, pesticides: 5.22%) alongside environmental variables (salinity: 5.61%, DOC: 5.57%). Historically contaminated and relatively unimpacted estuaries each demonstrated distinct fish communities, reflecting their associated catchment use. Our findings emphasise that while seasonal effects play a key role in shaping the community structure of fish in this region, agricultural contaminants are also important contributors in estuarine systems.

Development of Small-scale Integrated Hydroponics—Animal Waste Bioreactor (AWB) for Romaine Lettuce (Lactuca sativa L. var. longofolia) Production

As improper processing and disposal of animal waste cause negative impacts on the environment, the animal industry sector must shift to more sustainable practices to lessen these effects. Recently, the application of the circular economy concept in agriculture, using animal waste as part of nutrient cycling, has emerged as a sustainable approach. The study aims to develop and test the small-scale integrated hydroponics-animal waste bioreactor (AWB) for romaine lettuce production using chicken manure tea (CMT) derived from dried chicken manure as a primary nutrient source. Three integrated hydroponics-AWB systems, with varying concentrations of CMT at 1,000 ppm, 1,200 ppm, and 1,400 ppm total dissolved solids (maintained within an upper and lower bound of 50 ppm), were constructed, tested, and compared to conventional hydroponics that used a nutrient solution maintained at 1,000 ppm TDS. The test result suggests that the ideal concentration of CMT in the system is 1,000 ppm. Within the optimum manure tea concentration, the small-scale integrated hydroponics-AWB produced romaine lettuce with growth parameters comparable to conventional hydroponics. In addition, increasing the CMT concentration to 1,400 ppm negatively impacts the plant growth parameters of romaine lettuce. The developed small-scale integrated hydroponics-AWB system provides a viable approach for growing lettuce using animal waste as the major source of nutrients. The developed production system could help mitigate the negative environmental effects of improper handling and disposal of animal waste and dependence on chemical-based nutrient solutions in hydroponic crop production.

Fruit and vegetable disease detection and classification: Recent trends, challenges, and future opportunities

Fruits and vegetables are major sources of nutrients for the majority of the population across the globe. With the rapid increase in population, the objectives of the future agro-industry are to reduce product loss while increasing product quality and productivity considerably. Consequently, farmers need to be assisted with cutting-edge technologies for sustainable, eco-friendly, and efficient farming. Smart farming for early disease recognition and control is the current hot-spot research objective in the fruitage domain. The precision agriculture era has been revolutionized by federating cutting-edge technologies like machine learning, deep learning, and, the Internet-of-Things. However, the existing studies focused on the impact of individual technology on single or multiple cultivars of edible fruits or vegetables. Limited areas of the fruitage disease remain explored, necessitating further investigation into the research gaps and challenges identified for implementing the smart practices in real-field farmlands. In this paper, a comprehensive survey of recent advancements in fruit and vegetable disease identification and classification is presented. The technology-wise state-of-the-art findings, gaps, challenges, and future opportunities for fruitage disease recognition have been presented, covering 99 research articles. Moreover, the corpus of publicly available fruit and vegetable datasets has been investigated, with the existing gaps, improvements, and future requirements. The research paper concludes with challenges and a future outlook that promises to be a very significant and valuable resource for researchers working in the area of agronomic disease monitoring.

Hexanal Treatment for Improving the Shelf-life and Quality of Fruits: A Review

Fruits are rich sources of bioactive compounds such as lycopene, tannins, β-carotene, resveratrol, and lignan. These bioactive compounds’ antioxidative, antimicrobial, and antidiabetic properties are important in the human diet. Since fruits are one of the major sources of health-promoting nutrients for human consumption, they have high economic value. Ripening is a developmental process which involves changes in the colour, texture, taste, and metabolite composition of fruits, thus affecting their quality. In the market, the good quality of fruits depends on the ripening stage. Rapid ripening could shorten the shelf-life and quality of fruits. Shortened shelf-life causes fruit spoilage during post-harvest, transport, storage, and distribution. In turn, it will cause economic losses in the fruit market. Low-temperature storage is one of the techniques to prolong the shelf-life of fruits. However, this technique requires an expensive facility to achieve and maintain the low temperature. On the other hand, it has been reported that hexanal treatment could prolong the shelf-life and quality of fruits. It is also cheaper and easier to apply. However, the ripening inhibition mechanism of hexanal is not yet fully understood. The effectiveness of hexanal treatment on different fruits is also unclear. Numerous publications on hexanal treatment reported different formulations, techniques, and effectiveness rates on different fruits. Optimised formulation and technique are important to develop an efficient hexanal treatment strategy. Therefore, the mechanism, effectiveness, formulation, technique, and development of hexanal-based products to prolong the shelf-life of fruits are discussed in this review.

Effect of Rainfall on Water Parameters in Recreational Lakes in Heidelberg, Germany

This study evaluates the impact of precipitation on water quality in Heidelberg, Germany’s recreational lakes during sporadic rainfall events from August to September 2023. Data were collected from five stations, monitoring physicochemical properties and nutrient levels before and after rainfall. Measurements of dissolved oxygen, pH, conductivity, and redox potential were conducted in situ, while turbidity, nitrates, phosphates, sulphates, zinc, and copper levels were analyzed in the SRH Heidelberg water laboratory. Findings indicate pH levels increased due to dilution effects, while conductivity rose due to runoff, enhancing ion concentration in the lakes. Dissolved oxygen levels also increased, attributed to aeration from rainfall-induced surface turbulence. Redox potential decreased, reflecting atmospheric oxygen dissolution. Nutrient concentrations, including nitrates and phosphates, along with sulphates, declined post-rainfall, suggesting a dilution effect without significant impact from surface runoff. This outcome implies the absence of major nutrient and sulphate sources upstream. Heavy metals like zinc and copper also decreased in concentration, indicating no introduction through runoff or sediment transport. The study underscores the variability of water quality parameters across different lakes, influenced by factors such as water sources, surrounding land use, geological conditions, and lake characteristics. Overall, water quality improved post-rainfall, making the lakes suitable for recreational activities, with the study establishing a non-linear correlation among the water quality parameters and deducing the P ratio for each parameter.

Removal and release of microplastics and other environmental pollutants during the start-up of bioretention filters treating stormwater

Untreated stormwater is a major source of microplastics, organic pollutants, metals, and nutrients in urban water courses. The aim of this study was to improve the knowledge about the start-up periods of bioretention filters. A rain garden pilot facility with 13 bioretention filters was constructed and stormwater from a highway and adjacent impervious surfaces was used for irrigation for ∼12 weeks. Selected plants (Armeria maritima, Hippophae rhamnoides, Juncus effusus, and Festuca rubra) was planted in ten filters. Stormwater percolated through the filters containing waste-to-energy bottom ash, biochar, or Sphagnum peat, mixed with sandy loam. Influent and effluent samples were taken to evaluate removal of the above-mentioned pollutants. All filters efficiently removed microplastics >10 µm, organic pollutants, and most metals. Copper leached from all filters initially but was significantly reduced in the biochar filters at the end of the period, while the other filters showed a declining trend. All filters leached nutrients initially, but concentrations decreased over time, and the biochar filters had efficiently reduced nitrogen after a few weeks. To conclude, all the filters effectively removed pollutants during the start-up period. Before being recommended for full-scale applications, the functionality of the filters after a longer period of operation should be evaluated.

Controls on in-stream nitrogen loss in western Lake Erie tributaries

Management efforts to reduce cyanobacterial harmful algal blooms (cHABs) in the Great Lakes have focused on decreasing tributary inputs of phosphorus (P). Recent research has indicated that reduction of both P and nitrogen (N) can lessen cHABs severity. Microbially mediated N cycling in streambed sediment may reduce N riverine loads, yet little is known about in-stream N processing rates in the Maumee River Basin, a major source of nutrients to Lake Erie. During summer of 2019 and 2021, we sampled streambed sediment to measure potential nitrification and denitrification rates using the acetylene block method at 78 sites throughout the Maumee River network. We used structural equation models to identify indirect and direct drivers of denitrification. Precipitation was greater in 2019, resulting in a 67 % increase in mean discharge, 41 % of farm fields to be fallow, and a 50 % reduction in fertilizer use. During summer field surveys, median stream-water nitrate concentrations were not different between 2019 and 2021. Median denitrification rates were 13.3 mg N/m2/h and 31.2 mg N/m2/h, respectively, indicating high potential to remove N. Nitrate concentrations and nitrification rates were strong direct drivers of denitrification, especially in 2019 when coupled nitrification–denitrification sustained denitrification. Nitrate concentrations varied with land use. Notably, nitrate concentrations increased with the area of fallow land, which may indicate the presence of a legacy N source. These findings indicate that promoting streambed denitrification could reduce N loads to Lake Erie, but legacy N currently stored in the system may mask N reduction efforts.

Soil Characteristics of Casuarina, Eucalyptus, Melia and Teak Plantations in Tamil Nadu, India

Soil is the major source of nutrients for the growth of plants and determining the degree of soil physicochemical characteristics are very necessary to evaluate the soil fertility. The present investigation was conducted to study the soil properties of important plantations in the Cauvery delta zone of Tamil Nadu. The tree species selected for the study were Casuarina, Eucalyptus, Melia and Teak. Composite soil samples were collected from the selected plantations at three different depths; i.e., 0-15, 15-30 and 30-45 cm. The maximum OC (0.69 %) was recorded in Casuarina clonal plantation (CH-5) of &gt; 5 years at 0-15 cm depth. The mean soil pH in selected plantations of the Cauvery delta zone varied from 5.96 ± 0.08 to 7.40 ± 0.08. Nitrogen availability (307.57 kg ha-1) and potassium availability (339.57 kg ha-1) was maximum in &gt;5 years of Casuarina clonal plantation (CH-5). The available phosphorus content was high in the surface soils (0-15 cm) of &gt;6 years of E. camaldulensis (26.31 kg ha-1). The study has contributed to the understanding of the soil properties in different plantation species of clonal and seedling origin in Tamil Nadu.

Seasonal distribution of water masses and their impacts on nutrient supply in the southern Beibu Gulf

Dual water isotopes were investigated to reveal the seasonal distribution of water masses and their impacts on nutrient supply in southern Beibu Gulf. In summer and winter, the South China Sea (SCS) water (61–69%) contributed the most to the seawater in the southern Beibu Gulf, followed by the diluted water (24–34%), and the west-Guangdong coastal current (WGCC) (5–7%) had the minimum contribution. However, the major nutrient source shifted from the diluted water in summer (39–73%) to the SCS water (57–90%) in winter. The WGCC's impact on nutrient loads was relatively small (2–10% in summer, 4–34% in winter). Our results highlight the control of nutrient supply was the SCS water (winter) and diluted water (summer), with limited influence from the WGCC, providing new insights into the impact of water mass transportation and its nutrient supply in the Beibu Gulf.

Microscopic and transcriptomic characterization of Listeria monocytogenes aggregation and biofilm formation in cantaloupe juice

Plant exudate is likely the major nutrient source supporting the survival and biofilm formation of microorganisms in fresh produce processing environments. This study compared the impact of cantaloupe juice on the physiology and gene expression of Listeria monocytogenes (Lm) using microscopic and transcriptomic tools.Lm showed a strong autoaggregation and formed significantly more biofilms on stainless steel (SS) coupons when grown in cantaloupe juice in comparison to in TSB. SEM images revealed a different attachment profile of Lm on SS coupons. In TSB, Lm cells were mainly found in scratches and grooves of the metal surface, whereas, in cantaloupe juice they attached to the smooth surface as well. Lm planktonic and biofilm cells in cantaloupe juice exhibited stress-induced phenotypes, including strong cell elongation and increased proportion of cells with membrane permeability.Lm growth in cantaloupe juice resulted in distinct transcriptional profiles of both biofilm and planktonic cells in comparison to that in TSB. Functional annotation indicated that the significantly differentially expressed genes mainly participated in metabolism, signaling and stress response. Notably, certain pathways downregulated for planktonic cells were significantly upregulated for biofilm cells in cantaloupe juice compared to TSB, including ABC transporters, two-component system, quorum sensing, chemotaxis, and flagellar assembly.

Zoonotic risks of pathogens from dairy cattle and their milk-borne transmission.

Dairy products are major sources of high-quality protein and bioavailable nutrients and dairy production contributes to local, regional and national-level economies. Consumption of raw milk and raw milk products does, however, carry a zoonotic risk, as does direct contact with cattle by farm husbandry staff and other employees. This review will mainly focus on the latter, and deal with it from the standpoint of a well-developed dairy industry, using the example of the Netherlands. With regard to dairy cattle, the main bacterial pathogens are Salmonella spp., Listeria monocytogenes and Leptospira hardjo as well as Brucella abortus and Chlamydia abortus. The main viral pathogens associated with dairy are Rift Valley fever virus, rabies virus, cowpox virus and vaccinia virus. The main parasitological infections are Echinococcus granulosis, Cryptosporidium parvum and Giardia duodenalis, however, the last mentioned have mainly swimming pools as sources of human infection. Finally ectoparasites such as lice and mites and Trichophyton verrucosum may affect employees. Some pathogens may cause health problems due to contamination. Bacterial pathogens of importance that may contaminate milk are Campylolobacter jejuni, Escherichia coli, Mycobacterium avium subsp. paratuberculosis, Leptospira hardjo and Salmonella typhimurium. Excretion of zoonotic viruses in milk is negligible in the Netherlands, and the endoparasite, Toxocara vitulorum is mainly found in suckling and fattening calves, whilst the risk in dairy cattle is limited. Excretion of transmissible spongiform encephalopathies (TSEs) or mycoses in milk are not expected and are, therefore, not of importance here.Being aware of the risks and working according to hygiene standards can substantially limit zoonotic risks for employees. Additionally, diseased employees are advised to limit their contact with cattle and to indicate that they work with cattle when consulting a physician. To prevent zoonotic risks through excretion of pathogens in milk, standard hygiene measures are necessary. Further, using only pasteurised milk for consumption and/or processing of milk can considerably limit the risks. If these measures are not possible, well-constructed monitoring can be followed. Monitoring programmes already exist for pathogens such as for Salmonella spp., Leptospira hardjo and Mycobacterium avium subsp. paratuberculosis. For others, like Campylobacter jejuni and E. coli, programmes are not available yet as far as we know.

Synthesis of Galacto-oligosaccharides in Milk by Using Bifidobacterium bifidum β-galactosidases (Saphera 2600L and Nola Fit 5500) Immobilized on Chitosan Beads

The lactose intolerance—as a limiting factor for dairy milk consumption—has a high prevalence worldwide. Dairy milk and milk-derived products are major sources of multiple inorganic compounds and nutrients and thus are considered to be functional foods. β-galactosidases are able to hydrolyze lactose and are therefore widely applied for the production of lactose-free products. In addition, they are capable of the synthesis of galacto-oligosaccharides (GOSs); thus, the dairy industry has a special interest in applying them for the enrichment of dairy products with prebiotic GOSs. In this work, we studied two commercially available β-galactosidase products: Saphera 2600L and Nola Fit 5500. Both enzyme solutions contain a recombinant β-galactosidase of Bifidobacterium bifidum and have already been authorized for food industrial application, but the information about their hydrolytic and/or synthetic activities is only limited. After immobilization on chitosan beads, the enzymes were used for lactose hydrolysis and simultaneous synthesis of GOSs, by performing the reactions in pasteurized milk (skim milk). Both immobilized β-galactosidase exhibited elevated lactose hydrolysis (vmax increased from ~ 1 to ~ 4 mM/min) and GOS synthesis as compared to the free enzymes. The enzyme-coated beads were efficiently re-used at least 15 cycles; the residual lactose concentration was < 2 mg/ml after each cycle. After treatment, GOSs were present in ≤ 9% of the total sugar content, indicating that the prepared low-lactose milks were enriched in prebiotic GOSs. The application of immobilized Saphera 2600L and Nola Fit 5500 β-galactosidases may be implemented for the large-scale production of GOS-enriched low-lactose milk.Graphical

Combination of Measures to Restore Eutrophic Urban Ponds in The Netherlands

Urban ponds provide the most important public contact with surface waters, implying that good water quality is crucial to the quality of urban life. Three eutrophic urban ponds in the south of The Netherlands with a long history of eutrophication-related nuisance were studied and subjected to mitigating measures. The external nutrient load from a mixed sewer overflow to one of the ponds had already been dismantled prior to the study, in a second pond it was dismantled during, while in the third pond the major nutrient source (stormwater run-off from impervious surfaces) was left untouched. In order to rehabilitate the ponds, all were dredged to reduce the internal loading, the fish biomass was reduced, the banks were softened, macrophytes were planted, users were advised to minimize the feeding of the fish and waterfowl, and the external nutrient load was reduced in two of the ponds. The two ponds in which the major external load was reduced showed strongly improved water quality after the additional in-pond measures. In contrast, the pond with ongoing external loading from stormwater run-off showed only marginally improved water quality. This study underpins that stormwater run-off can be polluting and that mitigating measures should only be implemented when the system analysis has revealed their feasibility.

Nitrification in the water column of Lake Erie: Seasonal patterns, community dynamics, and competition with cyanobacterial harmful algal blooms

Abstract This study reports directly measured nitrification rates in the water column of western Lake Erie, which is affected by annual cyanobacterial harmful algal blooms, and across all three Lake Erie basins. Over three field seasons, 15NH4+ stable isotope tracers were employed to quantify nitrification rates, and relative abundances of ammonia-oxidizing bacteria and ammonia-oxidizing archaea were determined via qPCR. Nitrification rates ranged from undetectable to 1,270 nmol L-1 d-1 and were generally greatest in the western basin near the Maumee River mouth (a major nutrient source). Nitrification rates were highest in early summer, and often lowest during peak cyanobacterial harmful algal blooms months (August and September), before increasing again in October. In the western basin, nitrification was negatively correlated with cyanobacterial biomass. There were no consistent differences in nitrification rates between the three Lake Erie basins. Over the three years in western Lake Erie, ammonia-oxidizing bacteria and ammonia-oxidizing archaea were often present in high and similar abundances, but overall, ammonia-oxidizing bacteria exceeded ammonia-oxidizing archaea, particularly in 2017. No relationships were observed between nitrification rates and ammonia-oxidizing bacteria and ammonia-oxidizing archaea abundances. Thus, despite abundant ammonia-oxidizer DNA, lower nitrification rates during cyanobacterial harmful algal blooms suggest that nitrifiers were poor competitors for regenerated and available NH4+ during these blooms, as also observed in similar systems. Low nitrification rates during cyanobacterial harmful algal blooms could limit system nitrogen removal via denitrification, a natural pathway for its removal and a valuable ecosystem service. Lower denitrification rates allow more bioavailable nitrogen to remain in the system and support biomass and microcystin production; therefore, these results help explain how non-nitrogen-fixing cyanobacterial harmful algal blooms persist, despite low bioavailable nitrogen concentrations during these blooms, and support management efforts to reduce external nitrogen loading to eutrophic systems.