Observations of the Life Cycle and Movement of the Thraustochytrid Ulkenia amoeboidea (Bahnweg & Sparrow) from the North Sea*

SYNOPSIS Two isolates of the thraustochytrid Ulkenia amoeboidea (Bahnweg & Sparrow) were obtained from the North Sea. In both isolates, the limax ameba liberated from the thallus rapidly assumed a nematode-like shape and movement characteristic of several sporozoan trophozoites. On rounding up, it underwent repeated binary fission and produced biflagellate zoospores.     

Omega-3 biotechnology: Thraustochytrids as a novel source of omega-3 oils

Thraustochytrids are large-celled marine heterokonts and classified as oleaginous microorganisms due to their production of docosahexaenoic (DHA) and eicosapentaenoic (EPA) ω-3-fatty acids. The applications of microbial DHA and EPA for human health are rapidly expanding, and a large number of clinical trials have been carried out to verify their efficacy. The development of refined isolation and identification techniques is important for the cultivation of thraustochytrids. With a high proportion of lipid biomass, thraustochytrids are also amenable to various production strategies which increase omega-3 oil output. Modifications to the existing lipid extraction methods and utilisation of sophisticated analytical instruments have increased extraction yields of DHA and EPA. Other metabolites such as enzymes, carotenoids and extracellular polysaccharides can also be obtained from these marine protists. Approaches such as the exploration for more diverse isolates having fast growth rates, metabolic engineering including gene cloning, and growing thraustochytrids on alternate low cost carbon source, will further enhance the biotechnological potential of thraustochytrids.     

Biotransformation of PCBs in Contaminated Sludge: Potential for Novel Biological Technologies

In this study, the biological transformation of polychlorinated biphenyls (PCBs) was investigated in sludge from the Ralston Street Lagoon (RSL), a United States Environmental Protection Agency (USEPA) designated Toxic Substances Control Act (TSCA) site, in Gary, IN. A biological tilled soil reactor (BTSR) operating under cycling anaerobic‐aerobic conditions and vermicomposting bioreactors (VBs) inoculated with Eisenia foetida earthworms were both systematically investigated. Sludge heavily contaminated with PCBs (> 500 ppm PCB as Aroclor 1248) was loaded into the BTSRs and amended sequentially with PCB‐dechlorinating anaerobic sediments and then aerobic PCB biodegrading microbes. The VBs were loaded with sludge mixed in varying ratios with sterile soil and then inoculated with earthworms. Bioreactors were monitored for the duration of the studies (ranging from four to nine months) and samples were regularly removed, extracted and analyzed for PCB congener content. Appropriate biotic and negative abiotic controls were maintained under the various conditions to quantify and measure the biological transformation of the PCB's. All samples were analyzed for PCB congener concentrations by Soxhlet extraction followed by gas chromatography with electron capture detection (ECD). In the BTSRs loaded initially with 500 ppm of PCBs, a 75 % reduction of total PCB was obtained while the BTSR loaded with 140 ppm PCBs revealed only a 25 % reduction in total PCB level. Sample analyses from the VBs demonstrated total PCB reductions ranging from 55 to 66 %, although worm‐free control reactors showed PCB attenuations from 48 to 68 %. Analysis of earthworms showed an increase in PCB levels in the earthworm biomass, with concentrations reaching as high as 313 ppm. Mass balance analysis of the VB results demonstrated that most of the PCBs were bioaccumulated, although some PCB elimination was demonstrated. The results from both the anaerobic‐aerobic cycling BTSR and VB investigations demonstrate potential for application for site clean‐up and possible bioremediation of the Ralston Street Lagoon sludge.     

Induction of apoptosis and lipogenesis in human preadipocyte cell line by n −3 PUFAs

We examined the effect of n ?3 PUFAs (polyunsaturated fatty acids) on the growth and maturation of human preadipocyte cell line AML‐I. On day 3 of the culture, n ?3 fatty acids such as DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid), but not n ?6 fatty acid LA (linoleic acid), induced growth arrest accompanied by the appearance of characteristics of apoptosis in AML‐I cells at concentrations between 250 and 500 μM by Annexin V‐FITC staining. In Western blotting analysis, the loss of NF‐κB, Bcl‐2 and p‐Akt and the accumulation of Bad and Akt were observed in the cytoplasmic protein from the EPA‐treated cells. Exposure of AML‐I to EPA or DHA increased the cytoplasmic lipid accumulation compared with the vehicle‐treated cells in a time‐dependent manner during 4 and 6 days culture period by Oil Red O staining. The expression of FAS (fatty acid synthase) and PPAR‐γ (peroxisome proliferator‐activated receptor‐γ) were increased in EPA‐treated cells. These results suggest that EPA and DHA promote differentiation, inhibit proliferation and induce apoptosis in preadipocyte cell line AML‐I.     

Taxonomic rearrangement of the genus Schizochytrium sensu lato based on morphology, chemotaxonomic characteristics, and 18S rRNA gene phylogeny (Thraustochytriaceae, Labyrinthulomycetes): emendation for Schizochytrium and erection of Aurantiochytrium and Oblongichytrium gen. nov.

The genus Schizochytrium sensu lato has been characterized by successive binary division of its vegetative cells. However, the molecular phylogeny strongly suggests that this genus is not a natural taxon, because the original and recorded strains that have been identified as Schizochytrium spp. separately form three well-supported monophyletic groups in the 18S rRNA gene tree. These three groups are clearly distinguishable by their combined morphological characteristics and the profiles of the polyunsaturated fatty acids and carotenoid pigments they contain, although these are hard to distinguish using only a single feature. Therefore, three different genera are proposed to accommodate these three groups, i.e., Schizochytrium sensu stricto, Aurantiochytrium, and Oblongichytrium gen. nov.     

Unclassified Protists of Arthropods: The Ultrastructure of Nephridiophaga periplanetae (Lutz & Splendore, 1903) N. Comb., and the Affinities of the Nephridiophagidae to Other Protists

Observations by electron microscopy were conducted on Coelosporidium periplanetae (Lutz & Splendore, 1903) Swarczewsky, 1914, an extracellular sporogenic protist in the lumen of the Malpighian tubules of Blatta orientalis Linn., 1758 and other domiciliary cockroaches. Results generally agreed with earlier studies by light microscopy but also allowed a more complete characterization of the species. Some outstanding features of the protist were: amoeboid multinucleate stages (plasmodia) capable of producing cytoplasmic projections for attachment to microvilli of tubules, endogenous formation of spores, differentiation of “generative” and “somatic” nuclei in plasmodia undergoing spore formation, polarized early sporoblasts (a nucleus on one half and a chondriome on the other), and biconcave, ovoid, non-polarized spores that are retained until maturation by the plasmalemma and residual cytoplasm of the original plasmodium. The new combination Nephridiophaga periplanetae is proposed based on this new, updated information. The family name Nephridiophagidae Sprague, 1970 is resurrected to include N. periplanetae and eleven other species of protists in the Malpighian tubules of arthropods, mostly insects in the orders Dictyoptera and Coleoptera. According to its characteristics, the family Nephridiophagidae cannot be included into any of the currently recognized phyla of protists. It is suggested that it should be temporarily treated as an incertae sedis group of Protista.     

Production of kojic acid by Aspergillus species: Trends and applications

Kojic acid (KA), produced mainly by Aspergillus species, is a product of fungal secondary metabolism and has great potential in biotechnological applications. The use of KA has steadily increased, chiefly in the pharmaceutical industry, where KA is used for skin lightning. The market for KA has grown considerably in recent years and is expected to reach $39 million by 2026. In this review, we summarise the relevant information regarding the application of KA, describe the optimal cultivation conditions for Aspergillus species used in the production of KA, and assess the prospects for the KA market. Based on our findings, we established that the highest yields of KA can be achieved using submerged fermentation with glucose and yeast extract as the primary sources of carbon and nitrogen, respectively. Furthermore, according to literature, the main species/strains reported as the best producers of KA are Aspergillus flavus (44-L), Aspergillus oryzae (AR-47 and NRRL 484), and Aspergillus terreus (C5-10 mutant of the strain PTCC 5283). Given the commercial importance of KA and the growing demand for this natural product, further studies are needed to identify novel strains of Aspergillus as potential high producers of this acid. Similarly, it will be desirable to identify novel sources of substrate for the low-cost production of KA, thereby promoting its production for use in pharmaceutical, healthcare, and other potential industrial applications. In addition, given the current limited knowledge regarding the biosynthetic pathway of KA, further studies are required to elucidate that biosynthetic pathway.     

Taxonomic rearrangement of the genus Ulkenia sensu lato based on morphology, chemotaxonomical characteristics, and 18S rRNA gene phylogeny (Thraustochytriaceae, Labyrinthulomycetes): emendation for Ulkenia and erection of Botryochytrium, Parietichytrium, and Sicyoidochytrium gen. nov.

The genus Ulkenia is characterized by the naked protoplast stage within its life cycle. However, the 18S rRNA gene tree clearly shows that this genus is not a natural taxon, because our own isolates and reported strains separately form four well-supported monophyletic groups. These four groups are clearly distinguishable by their profiles of polyunsaturated fatty acids and carotenoid pigments and cell and colony morphology, e.g., persistence of sporangial wall, manner of the cell cleavage at the zoospore formation, and development of the ectoplasmic nets. Therefore, the four groups are assigned to four genera including three new genera, i.e., Ulkenia sensu stricto, Botryochytrium, Parietichytrium, and Sicyoidochytrium gen. nov.     

植物激素对破囊壶菌生长与产DHA的影响

研究了植物激素对破囊壶菌(Thraustochytrium roseum) MF2产DHA的影响作用。实验结果表明：植物激素对T.roseum MF2的生长和产DHA有很大影响;赤霉素(GA)能促进DHA的合成,6苄基腺嘌呤(BA)能显著促进T.roseum　MF2的生长,二者的配合使用能明显增加DHA的产量;培养基中适宜的添加量为2mg/L GA和3mg/L BA,可使DHA产量达到982mg/L。     

Optimizing the Production of Bacterial Cellulose in Surface Culture: Evaluation of Product Movement Influences on the Bioreaction (Part 2)

The common way for the production of bacterial cellulose in surface culture is to use culture boxes or beakers with vertical walls, where the maximum achievable thickness is around 4 cm. In order to improve this, it is necessary to study factors limiting the production. In part 1, the mass transfer influences of the substrate have been investigated. Now we look at a “wall effect”. It is noted that the growing cellulose is in contact with the wall of the box or beaker, and moves downwards into the nutrient broth as time proceeds. Experiments have been carried out where this wall contact was eliminated and a constant rate of production over several weeks was found. This indicates the importance of understanding the role of the wall in the usual surface culture.     

Anticipation of Risks and Benefits of Emerging Technologies: A Prospective Analysis Method

Methods for the identification, evaluation, and control of hazards are well recognized, whereas a method for the anticipation of hazards has eluded the field of industrial hygiene. The Emerging Technologies Team at the National Institute for Occupational Safety and Health has developed a method for anticipating not only occupational hazards but also potential benefits of emerging technologies for occupational safety and health. This method incorporates forecasting tools with a prospective assessment step into the risk assessment model, stresses research results as an iterative driver in the assessment, and depends on inherently safer design to eliminate or reduce hazards. An iterative process that involves the occupational safety and health professional as a team member in the development of emerging technologies is recommended.     

Distributions and Biomass of Benthic Ciliates,Foraminifera and Amoeboid Protists in Marine,Brackish, and Freshwater Sediments

The quantitative importance of ciliates, foraminifers, and amoebae was investigated in marine, brackish, and freshwater sediments from 15 littoral stations. Total protozoan communities were usually dominated by ciliates in term of abundance, while amoebae often dominated in terms of biomass. Applying the biomass‐metabolic rate equation, ciliates, amoebae, and foraminifera were estimated to contribute 66% of the total abundance and 33% of the biomass, but up to 55% of the combined metabolic rate to the micro‐ and meiobenthos in the 15 sediments. Statistical analyses using ciliate data demonstrated: (1) species composition and community structures represented significant differences between freshwater and marine/brackish sediments, and subsequently between temperate and arctic sampling sites; (2) the occurrence of dominant ciliates and their allocation to feeding types indicated that herbivory was the most common feeding strategy in these sediments; (3) multivariate analyses showed all of the tested environmental factors (temperature, salinity, silt/clay, carbon, nitrogen, and chlorophyll a) to be important to varying degrees, but especially the combination of salinity, temperature, and silt/clay. Multiple factor effects or comprehensive influences might be important in regulating the distribution of protozoa in sediments. The importance of protozoa in sediment systems and the potential ecological significance of cysts are discussed.     

Optimizing the Production of Bacterial Cellulose in Surface Culture: A Novel Aerosol Bioreactor Working on a Fed Batch Principle (Part 3)

Parts 1 and 2 have shown that the rate of production of bacterial cellulose stagnates because of the limitation of substrate supply and a wall effect, which hinders the removal of the product from the active cell zone. This paper demonstrates, how both of these problems can be eliminated in a novel bioreactor, where the substrates (mainly glucose and oxygen) are both fed directly to the surface of the product cellulose. This involves the generation of an aerosol spray of glucose and its even distribution to the living bacteria on the medium‐air interface. The apparatus was built and operated up to eight weeks with a constant rate of cellulose production. The aerosol system provides the basis for an economic production of bacterial cellulose in surface culture.     

Mechanisms for the increase in phosphorus uptake of waterlogged plants: soil phosphorus availability, root morphology and uptake kinetics

Waterlogging frequently reduces plant biomass allocation to roots. This response may result in a variety of alterations in mineral nutrition, which range from a proportional lowering of whole-plant nutrient concentration as a result of unchanged uptake per unit of root biomass, to a maintenance of nutrient concentration by means of an increase in uptake per unit of root biomass. The first objective of this paper was to test these two alternative hypothetical responses. In a pot experiment, we evaluated how plant P concentration of Paspalum dilatatum, (a waterlogging-tolerant grass from the Flooding Pampa, Argentina) was affected by waterlogging and P supply and how this related to changes in root-shoot ratio. Under both soil P levels waterlogging reduced root-shoot ratios, but did not reduce P concentration. Thus, uptake of P per unit of root biomass increased under waterlogging. Our second objective was to test three non-exclusive hypotheses about potential mechanisms for this increase in P uptake. We hypothesized that the greater P uptake per unit of root biomass was a consequence of: (1) an increase in soil P availability induced by waterlogging; (2) a change in root morphology, and/or (3) an increase in the intrinsic uptake capacity of each unit of root biomass. To test these hypotheses we evaluated (1) changes in P availability induced by waterlogging; (2) specific root length of waterlogged and control plants, and (3) P uptake kinetics in excised roots from waterlogged and control plants. The results supported the three hypotheses. Soil P avail-ability was higher during waterlogging periods, roots of waterlogged plants showed a morphology more favorable to nutrient uptake (finer roots) and these roots showed a higher physiological capacity to absorb P. The results suggest that both soil and plant mechanisms contributed to compensate, in terms of P nutrition, for the reduction in allocation to root growth. The rapid transformation of the P uptake system is likely an advantage for plants inhabiting frequently flooded environments with low P fertility, like the Flooding Pampa. This advantage would be one of the reasons for the increased relative abundance of P. dilatatum in the community after waterlogging periods. Received: 15 February 1997 / Accepted: 20 May 1997     

Marine Antimicrobial Peptides: A Promising Source of New Generation Antibiotics and Other Bio-active Molecules

International Journal of Peptide Research and Therapeutics - Multidrug resistant pathogenic microorganisms have created a global health crisis. This resistance emerged due to the improper use of...     

LiSET: A Framework for Early‐Stage Life Cycle Screening of Emerging Technologies

While life cycle assessment (LCA) is a tool often used to evaluate the environmental impacts of products and technologies, the amount of data required to perform such studies make the evaluation of emerging technologies using the conventional LCA approach challenging. The development paradox is such that the inputs from a comprehensive environmental assessment has the greatest effect early in the development phase, and yet the data required to perform such an assessment are generally lacking until it is too late. Previous attempts to formalize strategies for performing streamlined or screening LCAs were made in the late 1990s and early 2000s, mostly to rapidly compare the environmental performance of product design candidates. These strategies lack the transparency and consistency required for the environmental screening of large numbers of early‐development candidates, for which data are even sparser. We propose the Lifecycle Screening of Emerging Technologies method (LiSET). LiSET is an adaptable screening‐to‐LCA method that uses the available data to systematically and transparently evaluate the environmental performance of technologies at low readiness levels. Iterations follow technological development and allow a progression to a full LCA if desired. In early iterations, LiSET presents results in a matrix structure combined with a “traffic light” color grading system. This format inherently communicates the high uncertainty of analysis at this stage and presents numerous environmental aspects assessed. LiSET takes advantage of a decomposition analysis and data not traditionally used in LCAs to gain insight to the life cycle impacts and ensure that the most environmentally sustainable technologies are adopted.     

Microbial Production of Hydrogen by Mixed Culture Technologies: A Review

With its high energy content and clean combustion, hydrogen is recognized as a renewable clean energy source with enormous potential. Biological hydrogen production is a promising alternative with significant advantages over conventional petroleum‐derived chemical processes. Sustainable hydrogen production from renewable resources such as cassava, wastewater, and other agricultural waste is economically feasible for industrial applications. So far, the major bottlenecks in large‐scale biological hydrogen production are the low production rate and yield. This review discusses the various factors that affect the metabolic pathways of dark hydrogen production, and highlights the state‐of‐the‐art development of mixed culture technology. The aim of this review is to provide suggestions for the future directions of mixed culture technology, as well as by‐product valorization in dark fermentation.