Fish Pond Sediments Research Articles

ASSESSMENT OF CONTAMINATION AND POLLUTION RISKS CAUSED BY HEAVY METALS IN FISH POND SEDIMENTS

Pollution by heavy metals poses a significant risk to human health and ecology through the food web. Metal contamination in fish pond sediments can be caused by improper waste management and the overuse of artificial feed to increase output and profit. By using an atomic absorption spectrometer to analyse heavy metals such as Cd, Mn, Pb, and Cr, this study aims to assess the contamination levels and pollution risk from bottom sediment samples taken from 12 different fish ponds in the Rajshahi City of Bangladesh. According to this investigation, the concentrations of the metals Pb, Mn, Cr, and Cd were 0.1188 to 1.5139, 0.1899 to 0.8483, 0.0292 to 0.0395, and 0.3017 to 1.6182 mg/kg, respectively. All results show that the metal contents of all the sediments studied around the area do not exceed the standard limit. The risk assessment of the sediments was evaluated based on the geoaccumulation index, enrichment factor, and contamination factor. The analysisindicated that Cd, Pb, and Cr accumulation are within the acceptable limit except for Mn. This study provides essential baseline data on heavy metal contamination, serving as a foundation for future research by focusing on identifying contamination sources, accumulation pathways, and element mobility from feed to fish and sediment to significantly reduce environmental risks and protect both ecosystem integrity and public health.

Poultry manure fertilization of Egyptian aquaculture ponds brings more cons than pros

Aquaculture is a crucial sector for Egyptian food production, providing a cheap source of animal protein while securing income and employment for a substantial part Egypt's population. Nile tilapia (Oreochromis niloticus) is the most commonly produced fish, usually farmed in earthen ponds around the Northern Delta Lakes. A common practice among farms is to fertilize ponds with chicken manure (CM) in order to increase nutrient levels and promote phytoplankton, consumed by the fish. However, with reports of use of antibiotics in Egypt's poultry sector, and that CM contains residues of antibiotics, antibiotic resistant pathogens and antibiotic resistance genes (ARGs) are production benefits large enough to compensate a potential health hazard?Using production data from 501 aquaculture farms and fish pond sediment from 28 ponds we evaluated potential benefits in yields and profitability for farms using CM for fertilization, and used qPCRs to screen sediments for three antibiotic resistance genes coding for resistance to the most commonly used antibiotics in the poultry sector. The analysis showed no significant benefits to fish yields or profitability in farms where CM was applied, but a risk of significantly increased nutrient loads. Meanwhile, we detected increased abundances of tetA and tetW resistance genes in fish pond sediment where CM was applied. With the risk of disseminating ARGs and causing eutrophication of local waterways, we recommend that Egyptian tilapia pond farmers refrain from using CM and adopt best management practices for increasing farm profitability in order to to reduce environmental and health hazards.

Distribution patterns and influential factors of pathogenic bacteria in freshwater aquaculture sediments.

Pathogenic bacteria, the major causative agents of aquaculture diseases, are a serious impediment to the aquaculture industry. However, the bioinformatics of pathogenic bacteria and virulence factors (VFs) in sediments, an important component of freshwater aquaculture ecosystems, are not well characterized. In this study, 20 sediment samples were collected from fish pond sediments (FPS), shrimp field sediments (SFS), fish pond sediment control (FPSC), and shrimp field sediment control (SFSC). Molecular biological information was obtained on a total of 173 pathogenic bacteria, 1093 virulence factors (VFs), and 8475 mobile genetic elements (MGEs) from these samples. The results indicated that (1) aquaculture patterns and sediment characteristics can affect the distribution of pathogenic bacteria. According to the results of the Kruskal-Wallis H test, except for Mycobacterium gilvum, there were significant differences (P < 0.05) among the four sediment types in the average abundance of major pathogenic bacteria (top 30 in abundance), and the average abundance of major pathogenic bacteria in the four sediment types followed the following pattern: FPS > SFS > FPSC > SFSC. (2) Pathogenic bacteria are able to implement a variety of complex pathogenic mechanisms such as adhesion, invasion, immune evasion, and metabolic regulation in the host because they carry a variety of VFs such as type IV pili, HSI-I, Alginate, Colibactin, and Capsule. According to the primary classification of the Virulence Factor Database (VFDB), the abundance of VFs in all four types of sediments showed the following pattern: offensive VFs > non-specific VFs > defensive VFs > regulation of virulence-related genes. (3) Total organic carbon (TOC), total phosphorus (TP), available phosphorus (AP), nitrite, and nitrate were mostly only weakly positively correlated with the major pathogenic bacteria and could promote the growth of pathogenic bacteria to some extent, whereas ammonia was significantly positively correlated with most of the major pathogenic bacteria and could play an important role in promoting the growth and reproduction of pathogenic bacteria. (4) Meanwhile, there was also a significant positive correlation between CAZyme genes and major pathogenic bacteria (0.62 ≤ R ≤ 0.89, P < 0.05). This suggests that these pathogenic bacteria could be the main carriers of CAZyme genes and, to some extent, gained a higher level of metabolic activity by degrading organic matter in the sediments to maintain their competitive advantage. (5) Worryingly, the results of correlation analyses indicated that MGEs in aquaculture sediments could play an important role in the spread of VFs (R = 0.82, P < 0.01), and in particular, plasmids (R = 0.75, P < 0.01) and integrative and conjugative elements (ICEs, R = 0.65, P < 0.05) could be these major vectors of VFs. The results of this study contribute to a comprehensive understanding of the health of freshwater aquaculture sediments and provide a scientific basis for aquaculture management and conservation.

Mercury distribution, exposure and risk in Poyang Lake and vicinity, China

Mercury (Hg), especially methylmercury (MeHg), which is highly neurotoxic, is a global pollutant that can affect human health because of its accumulation in aquatic products. Poyang Lake, an inland lake in China, has been significantly affected by human activity, yet there is limited understanding of local mercury contamination and potential exposure pathways to humans. In this study, we explored the risks of mercury exposure by sampling sediments, plants, and aquatic organisms in the lake and surrounding areas and analyzing total Hg (THg) and MeHg levels. Sediment sampling was conducted at the main lake, rivers, rice paddies, and fishponds. Two dominant species of plants and 15 species of aquatic organisms were sampled and analyzed. We assessed the characteristics of mercury in sediments using the geo-accumulation index (Igeo), mercury exposure using the biomagnification factor (BMF) and biota sediment accumulation factor (BSAF), and risks using thresholds for adverse effects. The highest THg concentrations (137.04 ± 44.3 ng g−1 dw) were detected in the main lake sediments, whereas the highest MeHg concentrations (0.47 ± 0.6 ng g−1 dw) were detected in fishpond sediments. Mercury accumulation in the main lake sediments could be assessed as contaminated (Igeo > 0: 81.6%). Yellow catfish had the highest mercury concentration (THg 770.69 ± 199.7 ng g−1 dw; MeHg 741.93 ± 168.8 ng g−1 dw). Piscivores were adversely affected by carnivorous fish (50.8%), but all fish concentrations did not exceed the food safety standards recommend by China and the WHO. The mercury exposure results revealed significant Hg biomagnification and enrichment (BMF >1: 94.55%; BSAFmax = 1218). Long-term monitoring of aquatic organisms is warranted.

Profiling of antimicrobial resistance (AMR) and multi drug resistance (MDR) of &lt;em&gt;Escherichia coli&lt;/em&gt; isolates from livestock, wild animals and an ornamental fish farm in Polgahawela, Sri Lanka

The pattern of antimicrobial resistance (AMR) and the prevalence of multi drug resistance (MDR) of Escherichia coli (E. coli) isolates from livestock, wild animals and an ornamental fish farm were investigated in a selected area in Polgahawela, Sri Lanka. Sampling area of one square Km containing an ornamental fish farm, a broiler farm, cattle, goat, and backyard poultry which are located separately within the sampling area but not in an integrated farming system with its associated wildlife was mapped using GPS. Faecal samples were examined from 89 wild animals (terrestrial and avian species), 28 livestock animals (including poultry) as well as 40 samples from an ornamental fish farm (fish faecal material, pond water and pond sediment). E. coli was isolated using standard methods and AMR profiles were investigated for 12 antimicrobials using Kirby-Bauer disc diffusion method. Sixty nine percent (62/89) of wild animals and 86% (24/28) of livestock samples were positive for E. coli whereas the isolation rate was 17.5% (7/40) in the samples from the ornamental fish farm. A maximum of two randomly selected E. coli isolates from each sample, making a total of 164 isolates were tested for AMR of which 114, 43 and 7 were from wild animals, livestock and the ornamental fish farm, respectively. The E. coli isolates tested against 12 antimicrobials reflected that the proportions of E. coli isolates resistant to at least one antimicrobial were 30%, 63% and 71% in wild animals, livestock and the ornamental fish farm, respectively. Multidrug-resistant E. coli isolates were detected in wild animals, livestock and the samples from ornamental fish farm. Overall, according to the statistical analysis, E. coli isolated from livestock and the ornamental fish farm reflected a significantly higher chance of carrying AMR compared with E. coli from wild animals.

Exploring biochar and fishpond sediments potential to change soil phosphorus fractions and availability.

Phosphorus (P) availability in soil is paradoxical, with a significant portion of applied P accumulating in the soil, potentially affecting plant production. The impact of biochar (BR) and fishpond sediments (FPS) as fertilizers on P fixation remains unclear. This study aimed to determine the optimal ratio of BR, modified biochar (MBR), and FPS as fertilizer replacements. A pot experiment with maize evaluated the transformation of P into inorganic (Pi) and organic (Po) fractions and their contribution to P uptake. Different percentages of FPS, BR, and MBR were applied as treatments (T1-T7), T1 [(0.0)], T2 [FPS (25.0%)], T3 [FPS (25.0%) + BR (1%)], T [FPS (25%) +MBR (3%)], T5 [FPS (35%)], T6 [FPS (35%) +BR (1%)], and T7 [FPS (35%) + MBR (1%)]. Using the modified Hedley method and the Tiessen and Moir fractionation scheme, P fractions were determined. Results showed that various rates of MBR, BR, and FPS significantly increased labile and moderately labile P fractions (NaHCO3-Pi, NaHCO3-Po, HClD-Pi, and HClC-Pi) and residual P fractions compared with the control (T1). Positive correlations were observed between P uptake, phosphatase enzyme activity, and NaHCO3-Pi. Maximum P uptake and phosphatase activity were observed in T6 and T7 treatments. The addition of BR, MBR, and FPS increased Po fractions. Unlike the decline in NaOH-Po fraction, NaHCO3-Po and HClc-Po fractions increased. All Pi fractions, particularly apatite (HClD-Pi), increased across the T1-T7 treatments. HClD-Pi was the largest contributor to total P (40.7%) and can convert into accessible P over time. The T5 treatment showed a 0.88% rise in residual P. HClD-Pi and residual P fractions positively correlated with P uptake, phosphatase activity, NaOH-Pi, and NaOH-Po moderately available fractions. Regression analysis revealed that higher concentrations of metals such as Ca, Zn, and Cr significantly decreased labile organic and inorganic P fractions (NaHCO3-Pi, R 2=0.13, 0.36, 0.09) and their availability (NaHCO3-Po, R 2=0.01, 0.03, 0.25). Excessive solo BR amendments did not consistently increase P availability, but optimal simple and MBR increased residual P contents in moderately labile and labile forms (including NaOH-Pi, NaHCO3-Pi, and HClD-Pi). Overall, our findings suggest that the co-addition of BR and FPS can enhance soil P availability via increasing the activity of phosphatase enzyme, thereby enhancing plant P uptake and use efficiency, which eventually maintains the provision of ecosystem functions and services.

Aquaculture sediments amended with biochar improved soil health and plant growth in a degraded soil

Sustainable and safe management of aquaculture sediments is of great concern. Biochar (BC) and fishpond sediments (FPS) are rich in organic carbon and nutrients and thus can be used as soil amendments; however, it is not fully explored how the biochar amended fishpond sediments can affect soil properties/fertility and modulate plant physiological and biochemical changes, particularly under contamination stress. Therefore, a comprehensive investigation was carried out to explore the effects of FPS and BC-treated FPS (BFPS) on soil and on spinach (Spinacia oleracea L.) grown in chromium (Cr) contaminated soils. Addition of FPS and BFPS to soil caused an increase in nutrients content and reduced Cr levels in soil, which consequently resulted in a significant increase in plant biomass, chlorophyll pigments, and photosynthesis, over the control treatment. The most beneficial effect was observed with the BFPS applied at 35 %, which further increased the antioxidant enzymes (by 2.75-fold, at minimum), soluble sugars by 24.9 %, and upregulated the gene expression activities. However, the same treatment significantly decreased proline content by 74.9 %, Malondialdehyde by 65.6 %, H2O2 by 65.1 %, and Cr concentration in spinach root and shoot tissues. Moreover, the average daily intake analysis showed that BFPS (at 35 %) could effectively reduce human health risks associated with Cr consumption of leafy vegetables. In conclusion, these findings are necessary to provide guidelines for the reutilization of aquaculture sediments as an organic fertilizer and a soil amendment for polluted soils. However, more future field studies are necessary to provide guidelines and codes on aquaculture sediments reutilization as organic fertilizer and soil amendment for polluted soils, aiming for a more sustainable food system in China and globally, with extended benefits to the ecosystem and human.

Effects of organic fertilizers produced from fish pond sediment on growth performances and yield of Malabar and Amaranthus vegetables

The increasing intensification of aquaculture production requires the development of strategies to reduce its environmental impacts such as the pollution caused by the discharge of nutrient-rich sediments into local water bodies. This research was undertaken to investigate and evaluate the effect of using organic fertilizers produced from the pond sludge of freshwater snakehead fish (Channa striata) composted with organic amendments of peanut shells and coir fiber on growth performance indices and yields of Malabar spinach (Basella alba L.) and Amaranthus cruentus (Amaranthus L.) vegetables in the dry and wet seasons. An organic fertilizer quality experiment showed that the richest nutrient contents of the produced organic fertilizer were achieved when using 30% sludge mixed with 70% organic amendments (50% peanut shells + 50% coir fiber). This was selected and used for a vegetable cultivation experiment. For the reference treatment, only chemical fertilizer was applied, while in the other four treatments, 25, 50, 75, and 100% of the chemical fertilizer were substituted with the organic fertilizer. A 25–50% reduction in the chemical fertilizer application resulted in better growth performance indices and final yields than the other treatments, including the reference treatment, for both crops. The highest yields of Malabar spinach and Amaranthus cruentus vegetables were found in Treatment 3 (50% chemical fertilizer combined with 50% organic fertilizer), followed by Treatment 2 (25% organic fertilizer combined with 75% inorganic fertilizer) (P &amp;lt; 0.05). The results show that the reuse of sludge from snakehead fish ponds mixed with agricultural by-products as organic fertilizer for vegetables not only improves vegetable productivity but also reduces the costs of chemical fertilizer and decreases environmental pollution.

Effect of seasonal variations on compost quality of Eichhornia crassipes and Ipomoea carnea with fish pond sediment

Effect of seasonal variations on compost quality of Eichhornia crassipes and Ipomoea carnea with fish pond sediment

Characteristics of denitrification and anammox in the sediment of an aquaculture pond

Denitrification and anaerobic ammonium oxidation (anammox) are the key processes of nitrogen removal in aquaculture pond sediment. However, the reaction characteristics remain unclear. In this study, considering the sediment of conventional freshwater fishponds as the object, we set the optimal conditions of organic carbon, temperature, and total nitrates for denitrification and anammox. We found that the abundance and diversity of denitrifying bacteria and anammox bacteria in the two groups were significantly different. Candidatus brocadia is the most important bacteria in aquaculture pond sediments. The removal efficiencies of nitrite (NO2−-N), nitrate (NO3−-N), ammonia nitrogen (NH4+-N), and total organic carbon (TOC) in the anammox optimal conditions group were 97.99%, 93.05%, 54.92%, and 58.82%, respectively; however, those in the denitrification optimal conditions group were 99.82%, 86.10%, 45.74%, and 70.76%, respectively. Comparing each optimal condition, the removal efficiency of NO2−-N and TOC in the denitrification optimal condition groups was higher, whereas those of NO3−-N and NH4+-N were higher in the anammox optimal condition groups. We provide a reference for resolving nitrogen pollution in aquaculture pond sediments.

Screening of new Paenibacillus polymyxa S3 and its disease resistance of grass carp (Ctenopharyngodon idellus).

A new strain of Paenibacillus polymyxa S3 with antagonistic effects on 11 major fish pathogens (especially Aeromonas hydrophila), but had no toxicity to grass carp, was screened from the sediment of fishponds. In vivo colonization studies showed that strain S3 could be colonized and distributed in the gill and abdomen of the grass carp. Bioassay results showed that the weight growth rate of grass carp in the strain S3 oral group (16.01%) and strain S3 immersion group (16.44%) was significantly higher than those of the control group (8.61%). At the same time, the activities of ACP, AKP, CAT and GSH-Px in the serum of grass carp in oral and immersion groups were significantly higher than those of the control group. In addition, the treatment with strain S3 could significantly upregulate the expression of the antioxidant-related genes and immune-related genes Keap1, Nrf2, C3, LZM, IgM, TLR-4 and MyD-88 in grass carp tissues. The challenge test showed that strain S3 treatment significantly increased the survival rate of grass carp infected with Aeromonas hydrophila. Whole genome sequencing analysis showed that strain S3 had 16 active metabolite gene clusters, indicating that it had abundant gene resources, which provided important support for its development for fish microecological preparations. In summary, a new strain of Paenibacillus polymyxa S3 with antibacterial activity against a variety of fish pathogens was screened in this study and its probiotic function was evaluated, proving its potential value in fisheries.

Screening and evaluation of phosphate-solubilizing bacteria isolated from aquaculture ponds in a step-by-step strategy as potential biofertilizer.

The application of phosphate-solubilizing bacteria (PSB) has received little attention in aquaculture. In addition, the low efficiency of PSB as a biofertilizer in farm conditions is a major concern. Therefore, this study aims to isolate the PSB from sediment of earthen fishponds and evaluate with a more appropriate approach to ensure their effectiveness in increasing the bioavailability of phosphorus (P) in farm conditions. PSB was first isolated and selected using the National Botanical Research Institute's Phosphate (NBRIP) medium-containing tri-calcium phosphate (TCP) in solid and liquid media. Among 96 strains that were isolated, 11 strains identified by 16 s rRNA, belonging to the genera Pseudomonas and Acinetobacter, showed a higher ability to release P from TCP (48-170 mg L-1 ). Then, the efficiency of 11 strains was evaluated by combining different criteria. Among 11 selected strains, based on the ability to dissolve TCP and Ca-Phytate in culture medium, release P in sediment microcosm, and growth in a wide range of environmental conditions in fishponds, especially optimum growth at 4°C and pH above 8, Ps. deceptionensis strain Persian10 was selected as the most efficient strain for testing in aquarium conditions. In the last step, incubation of Persian10 in aquarium sediment (sterilized under gamma-ray) increased soluble P and had an impact on calcium phosphate, organic P and alkaline phosphatase activity; however, Persian10 had no impact on the concentration of iron phosphate and aluminium phosphate. Persian 10 strain can be considered a bio-fertilizer candidate in earthen fishponds as it expressed the ability to solubilize P in different conditions. It is very important to evaluate PSB in an appropriate process using a combination of different criteria to ensure optimal performance of PSB in farm conditions.

Nutrient release flux in Baiyangdian Lake with high disturbance

The cause analysis of overlying water eutrophication in high-disturbance areas is conducive to effective control measures. This paper analyzed the release risk and water quality of ammonia nitrogen (NH 3 –N) and orthophosphate (PO + 4 –P) in sediments of typical high-disturbance areas of Baiyangdian Lake and assessed the impact posed by the exchange flux of ammonia nitrogen and orthophosphate in sediments to the overlying water. The sediments in Nanliuzhuang and Caiputai fishponds were seriously polluted by nitrogen and phosphorus, respectively. The concentrations of NH 3 –N and PO + 4 –P in surface sediment pore water in the two lakes were significantly higher than those in the overlying water. Diffusion fluxes of NH 3 –N and PO + 4 –P were 1.89–3.38 and 0.99–3.05 mg m −2 d −1 at the sediment–water interface of fishponds in Nanliuzhuang district. Diffusion fluxes of NH 3 –N and PO + 4 –P at the sediment–water interface of fishponds in the Caiputai area separately ranged from −0.15 mg m −2 d −1 to 2.19 mg m −2 d −1 and from 0.41 mg m −2 d −1 to 2.14 mg m −2 d −1 , respectively. Results showed that fishpond sediment is an important source of orthophosphate in the overlying water. The overlying water NH 3 –N mainly comes from external inputs, such as bait feeding. Identification of key areas of endogenous risk and control of sediment NH 3 –N and PO + 4 –P endogenous release are the key links of water pollution control in Baiyangdian Lake.

Biomonitoring as a potential tool for water quality in tilapia culture: a case study of Baixa Mogiana region of São Paulo State, Brazil

The objectives of this study were to test an artificial substrate sampler method for aquaculture ponds and assess the water quality based on the benthic macroinvertebrate community living in fishpond sediment at four farms with tilapia production in the Baixa Mogiana region of São Paulo State, Brazil. Benthic macroinvertebrates were monitored every 15days for 3months. Approximately 500,000 organisms distributed in 47 taxa were collected. Chironomidae, Glossiphonidae, Hirudinidae, Libelullidae, Oligochaeta, and Polycentropodidae were present in all collected samples, with the dominance of Chironomidae in the benthic community. Polycentropodidae, a sensitive family to organic pollution, had a greater abundance in fish farms with better environmental conditions. Significant differences in dissolved oxygen and pH were observed among fishponds at different fish farms. Biomonitoring with artificial substrate is a simple and low-cost alternative to monitoring water quality of tilapia culture in fishponds. The artificial substrate sampling method was effective, but the evaluation of more critical conditions of water quality would improve the method and enhance the knowledge of taxa and ecology of macrobenthic organisms in fishponds.

Pollution and Release Characteristics of Nitrogen, Phosphorus and Organic Carbon in Pond Sediments in a Typical Polder Area of the Lake Taihu Basin

There is currently a lack of knowledge on the release characteristics of nutrients from artificial pond sediments in polder areas, resulting in problems in future management of such environments, including converting polders to lakes. In this study, sediment samples were taken from a fish pond and a lotus pond in a typical polder area of the Lake Taihu Basin in China. The total nitrogen (TN, 1760–1810 mg/kg), total phosphorus (TP, 1370–1463 mg/kg) and total organic carbon (TOC, 10.1–21.2 g/kg) contents were significantly higher than those found in sediments from the adjacent aquatic system, which indicates that the legacy of agricultural activities has had an obvious cumulative effect on pond sediment nutrients. The release behavior of TN, TP and TOC varied significantly, not only under disturbed and static conditions, but also from sediments sampled at different ponds and depths. During the disturbing condition, there were continuous releases of carbon and nutrients in the lotus pond sediments, while the fish pond sediments showed a higher release at the beginning. Under static release conditions, the release of TP in the surface and bottom sediments of the fish pond increased first, then decreased and stabilized within 24 h, while the release of the lotus pond showed a slow upward trend. Despite the lower concentration of nutrients and TOC, the lotus pond sediment showed a higher release rate. The results suggested that it is necessary to adopt different strategies for different types of ponds in the project of returning polders to lakes; it is especially important to pay attention to the release of nutrients from the bottom sediments of lotus ponds in the project management.

Herbal plants- and rice straw-derived biochars reduced metal mobilization in fishpond sediments and improved their potential as fertilizers

Fishpond sediments are rich in organic carbon and nutrients; thus, they can be used as potential fertilizers and soil conditioners. However, sediments can be contaminated with toxic elements (TEs), which have to be immobilized to allow sediment reutilization. Addition of biochars (BCs) to contaminated sediments may enhance their nutrient content and stabilize TEs, which valorize its reutilization. Consequently, this study evaluated the performance of BCs derived from Taraxacum mongolicum Hand-Mazz (TMBC), Tribulus terrestris (TTBC), and rice straw (RSBC) for Cu, Cr, and Zn stabilization and for the enhancement of nutrient content in the fishpond sediments from San Jiang (SJ) and Tan Niu (TN), China. All BCs, particularly TMBC, reduced significantly the average concentrations of Cr, Cu, and Zn in the overlying water (up to 51% for Cr, 71% for Cu, and 68% for Zn) and in the sediments pore water (up to 77% for Cr, 76% for Cu, and 50% for Zn), and also reduced metal leachability (up to 47% for Cr, 60% for Cu, and 62% for Zn), as compared to the control. The acid soluble fraction accounted for the highest portion of the total content of Cr (43–44%), Cu (38–43%), and Zn (42–45%), followed by the reducible, oxidizable, and the residual fraction; this indicates the high potential risk. As compared with the control, TMBC was more effective in reducing the average concentrations of the acid soluble Cr (15–22%), Cu (35–53%), and Zn (21–39%). Added BCs altered the metals acid soluble fraction by shifting it to the oxidizable and residual fractions. Moreover, TMBC improved the macronutrient status in both sediments. This work provides a pathway for TEs remediation of sediments and gives novel insights into the utilization of BC-treated fishpond sediments as fertilizers for crop production.

Shifts in structure and function of bacterial community in river and fish pond sediments after a phenol spill.

Phenol is widely used in industrial processes and has microbial toxicity. However, the effects of a phenol spill on the microbial community are not clear. The present study explored the changes of bacterial communities in river and fish pond sediments after a phenol spill. The bacterial richness and diversity in river sediments were lower on day 30 (36 days after the spill) than on day 0, while they increased in fish pond sediments. The structures and functions of bacterial communities in both river and fish pond sediments were changed, and a more dramatical variation was detected in fish pond sediments. In river sediments, Proteobacteria, Chloroflexi, Acidobacteria, Bacteroidetes, and Nitrospirae were the major bacterial phyla, and Chloroflexi was enriched. In fish pond sediments, genera Brevibacillus dominated bacterial communities initially, and bacterial composition showed a dramatic change on day 30. Most predicted metabolism functions, as well as genetic information processing functions of translation, replication, and repair, were enhanced in both river and fish pond sediments, while they showed an opposite change trend for xenobiotic degradation function. This work could strengthen our understanding of the effects of phenol spills on sediment bacterial communities in both lotic and lentic ecosystems.

Saccharpiscinols A-C: Flavans with Potential Anti-Inflammatory Activities from One Actinobacteria Saccharomonospora piscinae.

Phytochemical investigation and chromatographic separation of extracts from the actinobacteria strain Saccharomonospora piscinae that was isolated from dried fishpond sediment of Kouhu township, in the south of Taiwan, led to the isolation of three new compounds, saccharpiscinols A–C (1–3, respectively), and three new natural products, namely (2S)-5,7,3′,4′-tetrahydroxy-6,8-dimethylflavanone (4), methyl-4-hydroxy-2-methoxy-6-methylbenzoate (5), and (±)-7-acetyl-4,8-dihydroxy-6-methyl-1-tetralone (6). Compounds 4–6 were reported before as synthesized products, herein, they are reported from nature for the first time. The structures of the new compounds were unambiguously elucidated on the basis of extensive spectroscopic data analysis (1D- and 2D-NMR, MS, and UV) and comparison with literature data. The effect of some isolates on the inhibition of NO production in lipopolysaccharide-activated RAW 264.7 murine macrophages was evaluated. Saccharpiscinol A showed inhibitory activities against LPS-induced NO production.

Antimicrobial activities of microbially-synthesized silver nanoparticles against selected clinical pathogens in Akure, Nigeria

Silver nanoparticles (AgNPs) have stimulated interest of scientists due to their wide range of applications, including their potential antimicrobial activity. This study investigated the antimicrobial activities of AgNPs synthesized by rhizospheric soil and fish pond sediment microorganisms against selected clinical pathogens. The samples were cultured and organisms identified in accordance with standard procedures. The synthesis of AgNPs colloidal solution was monitored by UV-vis analysis. Presence of bands was determined by the Fourier Transform Infrared spectroscopy (FTIR). The antimicrobial activity of the synthesized AgNPs against selected clinical isolates was determined using agar well diffusion method. Ten species each of bacteria and fungi were isolated from the samples. Formation of AgNPs was indicated by colour transformation from yellow to brown. All synthesized AgNPs showed intense peak with wavelengths ranging of 410-440 nm in UV-vis. The FTIR revealed band at 3395 cm-1 and a strong peak at 3300-3500 cm-1. The AgNPs synthesized by some of the isolates exerted remarkable and varying degrees of antimicrobial activities against the susceptible test organisms. This study revealed that the microbially-synthesized AgNPs obtained from this study possess a high antimicrobial potency against most potential pathogens investigated, and, thus, can be exploited in the development of novel antimicrobial agents. Key words: Antimicrobial agents, microbial resistance, microorganisms, pathogens, silver nanoparticles, zones of inhibition.

A Novel Nitrobacteria-based Microbial Sensor for Water Detection

This paper described the development and application of a nitrifying bacteria sensor to monitor water toxicity. Four strains of bacteria with high efficiency nitrification, designated as F1, F4, Y2 and Z1, were isolated from fish pond sediment, and identified as Rhodococcus sp. (F1 and F4), Pseudomonas sp. (Y2) and Micrococcus sp. (Z1). The four bacterial strains were tested for their nitrifying capabilities. The results showed that the nitrifying rate of F1, F4, Y2 and Z1 reached 3.51, 3.43, 3.46, 3.52 mg/L·d respectively. The four strains were further cultivated for 21 days to investigate the effects of temperature, pH and inoculation amount on their NH4 +-N degradation ability. The cultivation showed that the four strains possessed optimal NH4 +-N degradation rate when temperature was 35?, pH value was 8.5, and inoculation amount was 30%. Furthermore, the carrier optimization test demonstrated that the nitrobacteria film prepared using 16% PVA, 1.2% SA, 2% NaNO3 and 75% CaCl2 had the best performance of toxicity detection. These results suggested that the nitrobacteria biosensor designed in this study was sensible and suitable for detecting water toxicity.