Production of poly-beta-hydroxybutyric acid by microorganisms accumulated from river water using a two-stage perfusion culture system

The perfusion culture system using a shaken ceramic membrane flask (SCMF) was employed to accumulate microorganisms separated from river water and to produce poly-beta-hydroxybutyric acid (PHB). Using a two-step culture method with a single SCMF, river microorganisms were cultured by separately feeding four representative carbon sources, n-propanol, lactic acid, methanol, and formic acid. After 140 h culture, the cell concentration and PHB content respectively reached 43 g/l and 35% when a propanol medium was fed. Using a two-stage perfusion culture with twin SCMFs, the seed cell mass was increased in the first SCMF and then supplied to the second flask for PHB production. As a consequence, the cellular PHB content rose to 51% in the second SCMF, while the cell concentration gradually increased to 25 g/l after 175 h perfusion culture. These results demonstrated the utility of the two-stage perfusion culture system for developing a cheap means of producing PHB coincident with wastewater treatment.     

Assessing organic contaminants in fish: comparison of a nonlethal tissue sampling technique to mobile and stationary passive sampling devices

As concerns mount over the human health risks associated with consumption of fish contaminated with persistent organic pollutants, there exists a need to better evaluate fish body burdens without lethally sampling many of the important commercial and sport species of interest. The aim of this study was to investigate two novel methods for estimating organic contaminants in fish that are a concern for both fish and human health. The removal of fish adipose fins, commonly done in mark-recapture studies with salmonid species, was evaluated as a nonlethal sampling technique to estimate concentrations of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in flathead catfish (Pylodictis olivaris), relative to those found in muscle fillets of the same fish. We also assessed the efficacy of using poly(dimethylsiloxane) (PDMS) as a mobile passive sampling device (PSD) attached directly to wild flathead catfish for assessing location-specific exposure of the fish to waterborne contaminants. The results of this study have demonstrated for the first time that organic contaminant concentrations in adipose fin were highly correlated (R2 = 0.87) with muscle fillet concentrations, indicating that the adipose fin of certain fishes may be used to accurately estimate tissue concentrations without the need for lethal sampling. Moreover, mobile PSDs attached directly to fish and used here for the first time accurately estimated ultratrace concentrations of waterborne PCBs and OCPs without any apparent harm to the fish, indicating that there are no practical or physical barriers to the use of mobile passive samplers attached to aquatic organisms. Among the many practical implications of this research, two potential priority items include the analysis of organic contaminants in farm-raised and sport fish intended for human consumption, without the economic and population losses associated with lethally sampling fish to obtain tissues, and identifying specific areas where fish may be accumulating large portions of their contaminant burden.     

Evaluation of parabens and their metabolites in fish and fish products: a comprehensive analytical approach using LC-HRMS

ABSTRACT

Parabens (PBs) are preservatives frequently used in cosmetics and personal care products as well as in the pharmaceutical and food industries due to their extensive defence mechanisms against multiple categories of microorganisms. Although they are considered safe when used within defined concentration limits, concern about their potential toxicity is still particularly active. Revealed as emerging pollutants, their incidence and behaviour in the aquatic environment have been studied, but there is only sporadic information when it comes to their extent and distribution in seafood. This study explores the presence of methyl- (MeP), ethyl-, propyl-, butyl-, and benzylparaben and their main degradation product 4-hydroxybenzoic acid (pHBA) in several fish species and bivalve samples with the aim to evaluate these food matrices as potentially important contamination sources of PB. Additionally, infant food containing fish was also enrolled in this survey: firstly, due to the absence of any information regarding this exceptionally important food item, and secondly, because of the necessity to estimate the PB content in the processed food. For this purpose, a fast, reliable and robust method was developed based on a simple liquid–liquid extraction followed by high-performance LC, coupled with a benchtop Q-Exactive Orbitrap high-resolution MS. The Q-Exactive parameters were carefully scheduled to achieve a balance between the optimal scan speed and selectivity, considering the limitations that are associated with generic sample preparation methodology. The method was validated through specificity, linearity, recovery, intra- and inter-day repeatability, LOD and LOQ. LOD and LOQ reached the ranges 0.65–3.5 and 2.15–11.7 ng g^?1, respectively, while overall recovery ranged from 77% to 118%. The PBs were more frequently present in bivalves than in fish samples with MeP as the main PB detected. No PBs were found in infant food, but pHBA was observed in all samples.     

Two-dimensional DNA gel electrophoresis mapping: a novel approach to diversity analysis of bacterial communities in environmental soil

The diversity analysis of bacteria is useful for the environmental assessment of soil. Traditional molecular-based methods such as denaturing gradient gel electrophoresis (DGGE) and terminal restriction fragment length polymorphism (T-RFLP) analysis achieve a low-resolution display of bacterial DNA fragments on a gel. To improve the resolution, a novel two-dimensional DNA gel electrophoresis (2-DGE) method was designed. This method can generate a high-resolution DNA map that facilitates the detailed analysis of soil bacteria. This map can be obtained by utilizing 2-DGE to separate genomic DNA fragments produced by polymerase chain reaction (PCR) amplification on the basis of chain length and G+C content. To develop this 2-DGE method further and to apply it to the assessment of bacterial diversity, we carried out a 2-DGE mapping of bacterial DNA fragments from different environmental soils and computed Shannon index as well as plotted rank-abundance curves on the basis of the relative intensity of each spot on the maps. DGGE mapping was also performed to compare the resolution of the two methods. 2-DGE mapping was capable of generating a higher resolution display by a factor of more than 2 using a DGGE fingerprint pattern on a piece of gel. Furthermore, the higher number of detected spots from the 2-DGE map enabled the assessment of differences in bacterial diversity in complex soil systems using a logarithmic normal rank-abundance plot.     

鱼类胶原蛋白及胶原活性多肽的研究进展

胶原蛋白(Collagen)是一种高分子蛋白质,丝状的胶原蛋白纤维,能使皮肤保持结实而有弹性.胶原蛋白由于其特有的生理活性及物理和化学特性,在医药、食品、化妆品等高附加值领域中得到广泛应用.从水产品中获取胶原蛋白或制备胶原活性肽成为国内外研究的热点.随着我国渔业的发展,水产品的综合利用也越来越引起人们的重视.在加工时产生出占鱼体总重约40%～55%的下脚料(包括鱼头、鱼皮、鱼鳍、鱼尾、鱼骨及其残留鱼肉),而这些废弃物是制备胶原蛋白的优良原料,对这些废弃物的再利用,不仅保护了环境还可提高水产品的附加值.本文简要介绍了来源于鱼类胶原蛋白的制备方法、种类、性质、鱼类胶原蛋白的研究现状、鱼类胶原蛋白水解物中的活性肽、鱼类胶原蛋白及其肽的应用,并分析了鱼类胶原蛋白开发前景.     

Occurrence of pharmaceuticals in river water and their elimination in a pilot-scale drinking water treatment plant

The occurrence of four beta blockers, one antiepileptic drug, one lipid regulator, four anti-inflammatories, and three fluoroquinolones was studied in a river receiving sewage effluents. All compounds but two of the fluoroquinolones were observed in the water above their limit of quantification concentrations. The highest concentrations (up to 107 ng L(-1)) of the compounds were measured during the winter months. The river water was passed to a pilot-scale drinking water treatment plant, and the elimination of the pharmaceuticals was followed during the treatment. The processes applied by the plant consisted of ferric salt coagulation, rapid sand filtration, ozonation, two-stage granular activated carbon filtration (GAC), and UV disinfection. Following the coagulation, sedimentation, and rapid sand filtration, the studied pharmaceuticals were found to be eliminated only by an average of 13%. An efficient elimination was found to take place during ozonation at an ozone dose of about 1 mg L(-1) (i.e., 0.2-0.4 mg of O3/ mg of TOC). Following this treatment, the concentrations of the pharmaceuticals dropped to below the quantification limits with the exception of ciprofloxacin. Atenolol, sotalol, and ciprofloxacin, the most hydrophilic of the studied pharmaceuticals, were not fully eliminated during the GAC filtrations. All in all, the treatment train was found to very effectively eliminate the pharmaceuticals from the rawwater. The only compound that was found to pass almost unaffected through all the treatment steps was ciprofloxacin.     

Determination of histamine by capillary zone electrophoresis using a low-pH phosphate buffer: application in the analysis of fish and marine products

 Histamine levels in samples of fish and marine products were determined by capillary zone electrophoresis using phosphate buffer at pH 2.44 and UV detection at 214 nm. A plot of the area of the peaks versus histamine concentration was linear over the range of 1–100 ppm with a correlation coefficient of 0.9996. Calibration using the height of the peak also gave good correlation, with a correlation coefficient of 0.9969, at concentrations between 1 ppm and 20 ppm. The recovery of added histamine in different samples of fish and fish products was, on average, 99.65%. The method described in this work was used for the quantitation of histamine in fish and fish products. Received: 19 March 1996/Revised version: 22 July 1996     

Screening of peptides with a high affinity to bile acids using peptide arrays and a computational analysis

Bile acid binding peptides have attracted attention for the improvement and prevention of hypercholesterolemia. In this study, screening of bile acid high affinity peptides was investigated using computationally-assisted peptide array analysis. Starting with the screening data obtained from a limited, random 6-mer library (2212 sequences), the peptides with a high affinity to bile acid were characterized by comparison of high- and low-affinity peptides using fuzzy neural network (FNN) analysis. The physical properties of amino acids at specific positions that contribute to bile acid binding activity were extracted as the structural rule; optimization was carried out using three repeated screening cycles of the rule extraction. The extracted structural rule indicates that Trp, Tyr, Phe, Leu, Ile and Val are enriched in bile acid binding peptides. The yields of bile acid binding peptides with an affinity of above the VAWWMY peptide (soystatin, control sequence) were significantly higher in the optimized structural rule (32.5%) compared to that of the random library (3.1%), and 6 peptides were obtained with above 2.0-fold increased binding activity.     

Detection of the spatiotemporal trends of mercury in Lake Erie fish communities: a Bayesian approach

The temporal trends of total mercury (THg) in four fish species in Lake Erie were evaluated based on 35 years of fish contaminant data. Our Bayesian statistical approach consists of three steps aiming to address different questions. First, we used the exponential and mixed-order decay models to assess the declining rates in four intensively sampled fish species, i.e., walleye (Stizostedion vitreum), yellow perch (Perca flavescens), smallmouth bass (Micropterus dolomieui), and white bass (Morone chrysops). Because the two models postulate monotonic decrease of the THg levels, we included first- and second-order random walk terms in our statistical formulations to accommodate nonmonotonic patterns in the data time series. Our analysis identified a recent increase in the THg concentrations, particularly after the mid-1990s. In the second step, we used double exponential models to quantify the relative magnitude of the THg trends depending on the type of data used (skinless-boneless fillet versus whole fish data) and the fish species examined. The observed THg concentrations were significantly higher in skinless boneless fillet than in whole fish portions, while the whole fish portions of walleye exhibited faster decline rates and slower rates of increase relative to the skinless boneless fillet data. Our analysis also shows lower decline rates and higher rates of increase in walleye relative to the other three fish species examined. The food web structural shifts induced by the invasive species (dreissenid mussels and round goby) may be associated with the recent THg trends in Lake Erie fish.     

Lead concentrations in fish and river sediments in the old lead belt of Missouri

Although active mining activities in the Old Lead Belt of Missouri ceased in 1968, old tailings piles remain and continue to impact the lead (Pb) concentrations in sediments and fish in the Big River and Flat River Creek in Missouri. A 3-year study was conducted that examined the Pb concentrations in organic-rich sediments, fish fillets, and fish whole bodies at 13 sites in these two rivers. The results showed that the sediments had significantly elevated Pb concentrations near and beyond the tailings piles compared with control sites upstream from the mining activity. The results also showed the Pb concentration in sediments correlated well with Pb concentrations in suckers (r = 0.86, p < 0.0001) and small sunfish (r = 0.82, p < 0.0001). Annual average Pb concentrations in sucker fillets ranged up to 0.67 microg/g (wet weight basis) and exceeded the World Health Organization guidelines of 0.3 microg/g (wetweight basis) at many of the sample sites. Fillets of bass, which feed at a higher trophic level, had much lower Pb concentrations than either suckers or small sunfish, and no bass fillet samples exceeded the WHO guideline. Whole body Pb concentrations in small sunfish were also determined and correlated strongly (r = 0.92, p = 0.0004) with sediment concentrations before leveling at a maximum of approximately 20 microg/g (wet weight basis).     

Predicting bioavailability and accumulation of organochlorine pesticides by Japanese medaka in the presence of humic acid and natural organic matter using passive sampling membranes

Adsorption to dissolved organic matter (DOM) may significantly decrease the freely dissolved concentration of many hydrophobic organic compounds and, hence, result in reduced bioavailability to aquatic organisms. Here, the suitability of using triolein-embedded cellulose acetate membrane (TECAM) as a biomimetic surrogate to assess the bioavailability of organochlorine pesticides (OCPs) in water in the presence of DOM was explored. The accumulation of OCPs was measured in TECAM and pelagic Japanese medaka (Oryzias latipes) in the laboratory after 12 h exposure to water containing different levels of Aldrich humic acid. Further, OCP uptake by TECAM and medaka in real aqueous environments was evaluated after 30 d exposures in two sites. Laboratory results showed that OCP uptake by medaka consistently decreased with increasing levels of humic acid in the range of 0-15 mg C/L in sample solutions. This tendency was closely mimicked by OCP accumulation in TECAM under the same conditions. Field results showed that TECAM accumulated similar OCP patterns as medaka (r2 = 0.92 for site 1 and r2 = 0.94 for site 2), although comparison of the in-field eight OCP concentrations in TECAM to those in medaka yielded approximately a factor of 3 (on a wet weight basis). These results suggest that the TECAM method can be used as a simple and useful tool to predict the bioavailability and bioaccumulation potential of poorly biotransformed organic compounds in pelagic fish in aqueous environment.     

Presence of lactobacilli in the intestinal content of freshwater fish from a river and from a farm with a recirculation system

Lactobacilli are Gram-positive and catalase negative rods commonly found in lactic acid fermented foods and in the gastrointestinal tract of mammals and birds. Few studies have described lactobacilli in freshwater fish. We analysed the presence of lactobacilli in the intestines of young and adult freshwater fish inhabiting a river environment and from fish reared in an aquaculture unit with a water recirculation system. Various species of lactobacilli were present in relatively high number in the intestines of edible fresh water fish from the river, especially in the warm season but in low numbers in the cold season. Lactobacilli were scarcely found in the intestines of edible farmed fish reared in a recirculation system in warm water. Lactobacilli are reported for the first time from the intestines of wild European eel, perch, rudd, ruffe, bleak, silver bream, chub, somnul and farmed African catfish. The two first fishes, and the last one are highly valuable species for fisheries and aquaculture. Additionally, improved methods for storage and bacteriological analysis of fish intestinal content are described. The natural presence of lactic acid bacteria in fish may be of great interest in producing fermented fish products worldwide.     

A new approach to the analysis of tannin concentration using a microelectronic biosensor

Wine tannins are essential to the astringency and color stabilization of red wine through the formation of tannin conjugates. It is important to determine the concentration of tannins during wine aging and fermentation. The aim of this study was to establish a new method that allows for real-time analysis of tannin content in wine and eliminates inconvenient processes, such as calibrations and/or enzyme reactions. The Folin-Ciocalteau spectrophotometry (FCS) was used a positive control and compared it with new microelectrode biosensor cyclic voltammetry (MBCV) method. The new approach was established that not only allows for real-time tannin detection but is also economical and does not require the use of a specific enzyme. The results are reproducible and provide a precise measurement of tannin content.     

Biofouling of ultrafiltration membrane by dairy fluids: Characterization of pioneer colonizer bacteria using a DNA metabarcoding approach

Biofouling of filtration membranes is a major quality and performance issue for the dairy industry. Because biofilms that survive cleaning cycles become resistant over time, prevention strategies limiting the adhesion of bacteria to membranes should be prioritized for sustainable control of biofouling. However, this cannot be achieved because the pioneer bacteria colonizing these membranes are still unknown. Consequently, the objective of this study was to characterize pioneer bacteria on the filtration membrane surface and to measure the effect of filtration operational parameters on their diversity. Thus, milk and cheese whey were filtered for 5 h in concentration mode at 10 and 40°C using a laboratory-scale crossflow filtration system equipped with flat-sheet ultrafiltration membranes. Pioneer colonizer bacteria found on membranes after a chlorinated alkaline cleaning cycle were identified using a metabarcoding approach targeting the 16S ribosomal RNA genes. Our results suggested that prevention strategies targeting biofouling should consider the nature of the filtered fluid and the feed temperature (36.15 and 5.09% of the variances observed on membranes, respectively), as well as the microbial environment of the dairy processing plant. In the future, it is hypothesized that cleaning prevention strategies will be specific to each dairy processor and their operational parameters.     

Evaluation of taste active peptides and amino acids from anchovy proteins in fish sauce by in silico approach

Food Science and Biotechnology - Enzymatic activity and microbial fermentation play a prominent role in the bioconversion of complex muscle tissue into smaller units of peptides and amino acids,...     

Seasonal variation in the calibration of a microwave fat: water content meter for fish flesh

A microwave fat: water content meter designed for use on pelagic fish has been found to exhibit seasonal changes in calibration. This has been examined in detail for sprats ( Sprattus sprattus ) and herring ( Clupea harengus ) and is ascribed in part to the seasonal changes in these species of the protein content, which influences the rotational mobility of water in the tissue. Various solutions to the problems are proposed.