Chemical composition and seasonal fluctuations of the edible green seaweed, Monostroma undulatum, Wittrock, from the Southern Argentina coast

The chemical composition of green seaweed, Monostroma undulatum, Wittrock, growing in the Southern Argentina coast, was studied. Samples were collected in Puerto Deseado, province of Santa Cruz (47 degrees 45'L.S., 65 degrees 55'L.W.), from October to December 1999 and 2000. It has been analyzed six sample during this period. Algae were washed with sea water and dried at room temperature for 24 hs. Moisture, nitrogen, lipids and ashes were determined according to AOAC; fiber (total, soluble and insoluble), according to Lahaye. After mineralization with nitric acid, sodium and potassium were determined by flame photometry, calcium by complexometric method, and phosphorus by Gomori's method. The ranges expressed per 100 g dry algae were: protein (Nx6.25): 12.89-21.85; ashes (g): 33.92-40.05; lipid (g): 0.32-1.47; total fiber (g): 14.36-19.6; digestible carbohydrates (calculated by difference) (g): 20.86-32.48; sodium (g): 7.39-13.11; potassium (g): 1.38-3.18; calcium (mg): 149-226; phosphorus (mg): 190-447; Vitamin C (mg): 159-455. These results show that this green seaweed is an important source for protein, fiber, macronutrients minerals and vitamin C, during the macroscopic period. There was an important fluctuation that must be taken into account to consider the commercial collection to use it in human nutrition.     

N-Halamine-Based Antimicrobial Additives for Polymers: Preparation, Characterization and Antimicrobial Activity

A series of 3-alkyl-5,5-dimethylhydantoin derivatives were prepared by reacting 5,5-dimethylhydantoin with alkyl bromides with different alkyl chain length (C-2 to C-22). Upon chlorination, the hydration derivatives were transformed into 1-chloro-3-alkyl-5,5-dimethylhydantoins (CADMH). The structures of the samples were fully characterized with FT-IR, (1)H NMR, UV, and DSC analyses. The antimicrobial functions of CADMH were challenged with 10(8-9) CFU/mL of Escherichia coli (gram-negative bacteria) and Staphylococcus aureus (gram-positive bacteria). All the samples provided a total kill of the gram-negative and gram-positive bacteria in less than 30 min. CADMH were used as antimicrobial additives for polymeric materials. It was found that the presence of as low as 1% of CADMH could provide the samples with potent antimicrobial functions. The structure-antimicrobial efficacy relationships of the CADMH were further discussed.     

Evaluation of the antimicrobial action of honey against Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Escherichia coli, Salmonella enteritidis, Listeria monocytogenes and Aspergillus niger. Evaluation of its microbiological charge

The evaluation of the microbiological charge present in Costa Rican samples as the evaluation of its antimicrobial activity over different microorganisms, including those associated to wound infections, will allow to emit criteria referred to its use in therapeutic treatments, specially as alternative therapy for cases involving antibiotic resistant bacteria. The microbiological charge of 25 honey samples, acquired in Costa Rican markets was evaluated through several indicators including total plate aerobic count, total plate anaerobic count, total aerobic spore count, total anaerobic spore count and molds and yeast count. Also, samples were inoculated in tubes with chopped meat media and plated in egg yolk agar in order to determine the presence of Clostridium botulinum. For the antimicrobial activity evaluation, the diffusion method in Muller Hinton agar was performed, testing different honey concentrations (100, 75, 50, 25, 12,5 and 6,25 % v/v) against Staphylococcus aureus (ATCC 25923), Staphylococcus epidermidis (UCR 2902), Pseudomonas aeruginosa (ATCC 9027), Escherichia coli (ATCC25922), Salmonella enteritidis (ATCC 13076), Listeria monocytogenes (ATCC 19116) and Aspergillus niger. The results obtained for the microbiological characterization of honey show that 91% of samples had counts equal or lower than 1,0 x 10(1) CFU/g. No positive result was obtained for the isolation of C. botulinum. 24 of the samples analyzed inhibited the growth of S. aureus even in a 25% v/v concentration, nevertheless, A. niger was no inhibited by any of the samples tested.     

水溶性聚季铵盐制备及其异养菌杀菌性能

以四甲基乙二胺和二氯乙醚为原料,采用聚合法制备水溶性聚季铵盐PODEDED,考察了PODEDED投加量、pH值、水温和杀菌时间对异养菌杀菌效率的影响. 结果表明,在投加量60 mg/L、杀菌时间8~24 h、pH值5~10、水温30~45℃条件下,PODEDED对异养菌的杀菌率大于99%,杀菌机理主要是其结构中的正电荷季铵根N+官能团和长链烷基上的疏水基、亲水基深入到异养菌细胞膜内的类脂层和蛋白层,破坏了控制细胞渗透的原生质膜,使胞内物质外泄,导致异养菌死亡. 合成的PODEDED可用于各种工业循环水系统及污水处理与回用中异养菌微生物的杀灭.     

Characterization of an organic filter medium for the biofiltration treatment of air contaminated with 1,2‐dichlorobenzene

Laboratory experiments were conducted to determine the potential for removing 1,2‐dichlorobenzene (1,2‐DCB) in gaseous phase by biofiltration. Experiments were carried out over 8 months in a steel tank (0.45 m³) using an organic filter medium composed of peat, maple wood chips, chicken manure and 1,2‐DCB‐contaminated soil. During the first 6 months, the biofilter was operated without injecting 1,2‐DCB in order to characterize the physicochemical, mechanical and microbiological properties of the filter bed. The results revealed that it is an excellent medium for both microbial development (up to 10⁹ cells for heterotrophic bacteria) and long‐term stability with a limited drop of pressure (30 cm of water) and no clogging. Over the final 2 months, the biofilter treated air laden with 1,2‐DCB (0.30 and 0.75 g m^?3) and the maximum elimination capacity reached was 9 g m^?3 h^?1 (inlet load of 13 g m^?3 h^?1), which represented 69% efficiency. Elimination performance was strongly dependent upon inlet concentration, sorption/desorption and biodegradation phenomena occurring in the filter medium. Sorption/desorption and biodegradation mechanisms during the start‐up period were characterized using the elimination efficiency (%). At the beginning of the 1,2‐DCB injection, the microorganisms were strongly impacted and sorption/desorption phenomena prevailed. With the decrease of the inlet concentration, biodegradation progressively increased to become the most important mechanism. It was concluded that biofiltration possesses an excellent potential for treating volatile chlorinated benzene, known to be recalcitrant to biodegradation. Copyright © 2003 Society of Chemical Industry     

On the origin of <Emphasis Type="Italic">cis</Emphasis>-vaccenic acid photodegradation products in the marine environment

The origin of 11-hydroxyoctadec-trans-12-enoic and 12-hydroxyoctadec-trans-10-enoic acids (photodegradation products of cis-vaccenic acid) in the marine environment was investigated. cis-Vaccenic acid is commonly used as a bacterial biomarker; however, in heterotrophic bacteria the observed rates of cis-vaccenic acid photodegradation are negligible. Here, two hypotheses explaining the source of the photoproducts were tested. According to the first hypothesis, the photoproducts originate from aerobic anoxygenic bacteria, i.e., photoheterotrophic organisms using bacteriochlorophyll-containing reaction centers. Alternatively, the photoproducts come from a heterotrophic bacterial community closely associated with senescent phytoplanktonic cells. cis-Vaccenic acid photodegradation was detected in both experimental setups. However, a detailed comparison of the cis-vaccenic acid photodegradation patterns with those observed in particulate matter samples of the DYFAMED station (Mediterranean Sea) suggests that photodegradation of heterotrophic bacteria attached to senescent phytoplanktonic cells constitutes the more likely source of cis-vaccenic acid oxidation products detected in situ.     

低频脉冲磁场对电厂循环冷却水异养菌的影响

从变频脉冲磁场方向的变化以及固定频率与扫频范围两个方向进行了低频脉冲磁场的杀菌实验。实验表明微生物生理功能在磁场作用下发生改变,变频脉冲电磁场既能抑制循环水中异养菌的生长,也能刺激异养菌的繁衍;当磁场方向与水流方向平行和垂直时能达到70%以上的杀菌率,其中磁场方向与水流方向平行时在11～17 kHz频率范围内的杀菌率达到82.64%。因此利用低频脉冲磁场进行杀菌时应确定有效的扫频范围,才能达到较好的杀菌效果。     

硫自养/异养协同反硝化深度脱氮处理三氯蔗糖生产废水

为解决工业废水普遍存在的氮污染问题及单一电子供体的反硝化技术存在的缺陷,在上流式高效流化床反硝化反应器中,本文以Na₂S₂O₃和葡萄糖为底物构建硫自养/异养协同反硝化脱氮系统,研究其对三氯蔗糖生产废水二级处理出水的深度脱氮效果。在(35±1)℃下,调整进水C/N/S为1.3/1/1.9,反应器在40~109天运行期间,达到较高的脱氮水平,NO{}_{\mathrm{3}}^{-}-N去除率均在93%以上,最大NO{}_{\mathrm{3}}^{-}-N去除负荷达到3.52kg/(m³·d),且在不投加pH缓冲剂的条件下,出水pH始终保持在7.0以上。硫自养/异养协同反硝化污泥的群落组成以自养反硝化菌和兼养反硝化菌为主,其占比分别为45.69%和25.38%,异养反硝化菌相对较少。其中Thiobacillus是相对丰度最高的自养反硝化细菌,占比39.02%。     

Listeria monocytogenes in vegetables minimally processed

The demand of vegetables minimally processed (ready-to-use) has increased partly due to the frequent use of the food services, where the salads are always included in the daily menus. The use of new technologies for processing and packaging has made possible to obtain a product ready to serve. Nevertheless the associated risk of the presence of emergent pathogens, such as Listeria monocytogenes seems to be involved. The aim of this work was to assess the microbiological quality of this kind of food. 120 samples of vegetables minimally processed ready-to-use were analyzed for their content of aerobic mesophilic bacteria, total and fecal coliforms and E. coli, and the presence of Shigella spp. Vibrio cholerae and Listeria monocytogenes. The TECRA UNIQUE LISTERIA, the BCM Listeria monocytogenes and the API LISTERIA systems, and the methods of molecular detection AccuProbe and GENE-TRAK were used for isolation and identification. E. coli was detected in approximately 30.3% of the vegetables used in this study. The genus Listeria was evidenced in 25% of the samples; 30% corresponded to L. monocytogenes. Shigella spp and Vibrio cholerae were not isolated. The findings of this study suggest the need of the microbiological control of the vegetables minimally processed ready-to-use to assure their quality and safety.     

新型吡唑啉衍生物合成与抑菌活性实验研究

根据α,β-不饱和醛酮亲核加成反应原理合成化合物L{[3-(4-N,N-dimethyl-pyenyl)-5-Anthracen-9-yl]-Pyrazoline}和化合物M[3-ferroceny-5-(Anthracen-9-yl)-Pyrazoline]。利用~1H NMR和~(13)C NMR对化合物进行结构表征,通过抑菌实验研究化合物抑菌生物活性。探析新型吡唑啉衍生物对革兰氏阳性菌、革兰氏阴性菌和真菌的抑菌效果,研究其结构变化对活性的影响。结果表明,化合物L和M对典型革兰氏阳性菌和典型革兰氏阴性菌有一定的抑菌效果,对真核细胞型微生物作用不明显。通过比较两者对细菌的作用结果(抑菌圈直径的大小),化合物L的抑菌作用明显强于化合物M,化合物L吡唑啉环连接N、N-二甲基苯环可能增强了抑菌生物活性。     

兼具脱氮和除磷性能菌株的优选

通过L9（34）正交试验和单因素实验优化培养条件,从七株不同菌属的异养硝化-好氧反硝化菌中优选兼具除磷性能菌株。结果表明：优选出的两株异养硝化-好氧反硝化菌分别为丛毛单胞菌WXZ-17和芽孢杆菌WXZ2-4,二者均具有厌氧除磷性能,磷化氢为重要除磷产物。优选的两株菌培养条件均为： T=32.0℃、 pH=6.50、氮源为蛋白胨＋氯化铵＋硝酸钠、总磷浓度为20.0 mg/L,相应的除磷率分别为25.6％和36.0％。在早期脱氮实验中已证实该两株菌脱氮效率分别为：89.7％和96.4％。筛选出的兼具脱氮和除磷性能的菌株使实现废水同步脱氮除磷成为可能。     

Do Scleractinian Corals Engage in Chemical Warfare Against Microbes?

Corals are constantly exposed to ubiquitous microbes. Detrimental effects of microbes on corals include surface fouling and disease. To prevent fouling and disease, corals need to resist microbial colonization and invasion. One way that this could be achieved is by chemical defense. Extracts from 100 scleractinian coral species (44 genera and 13 families) were screened for antimicrobial activity against seven microbe species (Alteromonas rubra, Photobacterium damsela, Vibrio harveyi, Vibrio alginolyticus, Vibrio parahaemolyticus, Synechococcus sp., and Staphylococcus aureus). Activity against Synechococcus sp. (a marine cyanobacterium) was recorded in 100 coral species, and eight of these coral species also inhibited the growth of marine bacteria. The extent of microbial colonization on coral surfaces was assessed in 20 scleractinian species to test the hypothesis that fewer microbes occur on corals that have antimicrobial compounds. Bacterial counts exceeded cyanobacterial counts on coral surfaces, and coral species with antibacterial activity had the fewest bacteria on their surfaces. Thus, corals with less heavily colonized surfaces chemically inhibit microbial colonization.     

生物法同步脱除SO_2和NO的实验研究

生物滴滤工艺常被用来净化可被生物降解的污染气体。在一个生物滴滤塔中进行硫酸盐还原菌(SRB)、脱氮硫杆菌(TD)和异养反硝化菌3种优势菌的混菌填料挂膜,驯化成熟后处理含SO2和NO的模拟工业废气。实验表明:维持喷淋液pH值为7—8,S2O32-质量浓度为3 g/L左右,喷淋密度为18 m3/(m2.h),SO2进气质量浓度为200—5 000 mg/m3,NO进气质量浓度为20—500 mg/m3时,SO2气体平均去除率为97.6%,NO气体平均去除率为51.4%。     

Nutritional and microbiological profile of soybean sausages available in Costa Rica

The nutritional and microbiological quality of 80 soybean sausage samples (50% frankfurter and 50% sausage mortadela) was studied. On average, the protein content was 17.5 g/100 g in sausage mortadela and 20 g/100 g in frankfurter. The mean total fat content was 5.5 g/100 g for both products. However when products of different manufacture industries were compared, a highly significant difference (p = 0.0000) in the fatty acids speciation between both groups and between samples of the same product were found. Bigger differences were found in the content of palmitic acid (C16:0), oleic acid (C18:1) and linoleic acid (C18:2). Cholesterol was not detected in samples analyzed. On average the atherogenicity index was 0.55 for sausage mortadela and 0.59 for frankfurter. A consumption of 25 grams of of soybean protein from these sausages can bring an intake of saturated fatty acids between 20-90% of the daily recommendation. Likewise, they can supply between 12-70% of the recommended daily polyunsaturated fatty acids. These variations are owing to the big difference in fatty acids speciation in each sausage brand. Around 20% of soybean sausages studied showed total coliform levels above 10(4)/g, being more frequent in sausage mortadela. Also 60% of this product and 10% of frankfurters showed psychrotroph levels of 10(6)/g. Clostridium perfringens, in levels above 10(2)/g was evidenciated in 5% of samples, Escherichia coli was not isolated from them. The findings of this study suggest the urgent need for implementing a quality control system for soybean sausages, before national health authorities consider to support nutritional campainings that promote their consumption.     

异养菌产率系数的测定研究

在活性污泥1号模型(ASM1)的基础上,采用间歇式呼吸计量法,在不同的F/M条件下(控制在0.03~0.05),分别测定了生物絮凝-再生工艺中的再生池污泥、好氧颗粒污泥、氧化沟污泥中的异养菌产率系数YH。结果显示,3种污泥异养菌产率系数分别为0.71、0.58、0.68g[COD]/g[COD]。测定结果与ASM1号模型中推荐的异氧茵产率系数的缺省值0.67g[COD]/g[COD]存在差异,并对差异的原因进行了分析。     

Three Microbial Musketeers of the Seas: Shewanella baltica,Aliivibrio fischeri and Vibrio harveyi,and Their Adaptation to Different Salinity Probed by a Proteomic Approach

Osmotic changes are common challenges for marine microorganisms. Bacteria have developed numerous ways of dealing with this stress, including reprogramming of global cellular processes. However, specific molecular adaptation mechanisms to osmotic stress have mainly been investigated in terrestrial model bacteria. In this work, we aimed to elucidate the basis of adjustment to prolonged salinity challenges at the proteome level in marine bacteria. The objects of our studies were three representatives of bacteria inhabiting various marine environments, Shewanella baltica, Vibrio harveyi and Aliivibrio fischeri. The proteomic studies were performed with bacteria cultivated in increased and decreased salinity, followed by proteolytic digestion of samples which were then subjected to liquid chromatography with tandem mass spectrometry analysis. We show that bacteria adjust at all levels of their biological processes, from DNA topology through gene expression regulation and proteasome assembly, to transport and cellular metabolism. The finding that many similar adaptation strategies were observed for both low- and high-salinity conditions is particularly striking. The results show that adaptation to salinity challenge involves the accumulation of DNA-binding proteins and increased polyamine uptake. We hypothesize that their function is to coat and protect the nucleoid to counteract adverse changes in DNA topology due to ionic shifts.     

N-苯甲酰基苯并异噻唑-3-酮硫代甲酰胺类化合物的合成及生物活性

通过1,2-苯并异噻唑啉-2(3H)-酮和硫代异氰酸苯甲酸酐类化合物反应,合成了7种N-苯甲酰基苯并异噻唑-3-酮硫代甲酰胺类化合物,用IR、MS、1HNMR、13CNMR对其结构进行了表征;活性测试表明,浓度为0.005mol/L的该类化合物溶液对鳗孤菌、拟态孤菌、溶藻弧菌、大肠杆菌和嗜水性单胞菌的抑菌率达40.5%~100%。     

Chemical Mediation of Ternary Interactions Between Marine Holobionts and Their Environment as Exemplified by the Red Alga Delisea pulchra

The need for animals and plants to control microbial colonization is important in the marine environment with its high densities of microscopic propagules and seawater that provides an ideal medium for their dispersal. In contrast to the traditional emphasis on antagonistic interactions of marine organisms with microbes, emerging studies lend support to the notion that health and performance of many marine organisms are functionally regulated and assisted by associated microbes, an ecological concept defined as a holobiont. While antimicrobial activities of marine secondary metabolites have been studied in great depth ex-situ, we are beginning to understand how some of these compounds function in an ecological context to maintain the performance of marine holobionts. The present article reviews two decades of our research on the red seaweed Delisea pulchra by addressing: the defense chemistry of this seaweed; chemically-mediated interactions between the seaweed and its natural enemies; and the negative influence of elevated seawater temperature on these interactions. Our understanding of these defense compounds and the functional roles they play for D. pulchra extends from molecular interactions with bacterial cell signaling molecules, to ecosystem-scale consequences of chemically-controlled disease and herbivory. Delisea pulchra produces halogenated furanones that antagonize the same receptor as acylated homoserine lactones (AHL)-a group of widespread intercellular communication signals among bacteria. Halogenated furanones compete with and inhibit bacterial cell-to-cell communication, and thus interfere with important bacterial communication-regulated processes, such as biofilm formation. In a predictable pattern that occurs at the ecological level of entire populations, environmental stress interferes with the production of halogenated furanones, causing downstream processes that ultimately result in disease of the algal holobiont.     

Homoserine Lactones,Methyl Oligohydroxybutyrates,and Other Extracellular Metabolites of Macroalgae‐Associated Bacteria of the Roseobacter Clade: Identification and Functions

Twenty‐four strains of marine Roseobacter clade bacteria were isolated from macroalgae and investigated for the production of quorum‐sensing autoinducers, N‐acylhomoserine lactones (AHLs). GC/MS analysis of the extracellular metabolites allowed us to evaluate the release of other small molecules as well. Nineteen strains produced AHLs, ranging from 3‐OH‐C10:0‐HSL (homoserine lactone) to (2E,11Z)‐C18:2‐HSL, but no specific phylogenetic or ecological pattern of individual AHL occurrence was observed when cluster analysis was performed. Other identified compounds included indole, tropone, methyl esters of oligomers of 3‐hydroxybutyric acid, and various amides, such as N‐9‐hexadecenoylalanine methyl ester (9‐C16:1‐NAME), a structural analogue of AHLs. Several compounds were tested for their antibacterial and antialgal activity on marine isolates likely to occur in the habitat of the macroalgae. Both AHLs and 9‐C16:1‐NAME showed high antialgal activity against Skeletonema costatum, whereas their antibacterial activity was low.     

Anti-Biofilm Performance of Three Natural Products against Initial Bacterial Attachment

Marine bacteria contribute significantly towards the fouling consortium, both directly (modern foul release coatings fail to prevent “slime” attachment) and indirectly (biofilms often excrete chemical cues that attract macrofouling settlement). This study assessed the natural product anti-biofilm performance of an extract of the seaweed, Chondrus crispus, and two isolated compounds from terrestrial sources, (+)-usnic acid and juglone, against two marine biofilm forming bacteria, Cobetia marina and Marinobacter hydrocarbonoclasticus. Bioassays were developed using quantitative imaging and fluorescent labelling to test the natural products over a range of concentrations against initial bacterial attachment. All natural products affected bacterial attachment; however, juglone demonstrated the best anti-biofilm performance against both bacterial species at a concentration range between 5–20 ppm. In addition, for the first time, a dose-dependent inhibition (hormetic) response was observed for natural products against marine biofilm forming bacteria.