Samuel P. Meyers

Application of Chitosan for Treatment of Wastewaters

Research has clearly demonstrated that the biopolymer chitosan (deacetylated chitin) can be used as an effective coagulating agent for organic compounds, as a chelating polymer for binding toxic heavy metals, as well as an adsorption medium for dyes and small concentrations of phenols and PCBs present in various industrial wastewaters. In these specific applications, chitosan appears more effective than other polymers such as synthetic resins, activated charcoal, and even chitin itself. In addition, the amino group in chitosan is an effective functional group that can be altered chemically for production of other chitinous derivatives with specific useful characteristics as effective absorptive agents. Chitosans exhibiting different physicochemical characteristics, i.e., molecular weight, crystallinity, deacetylation, particle size, and hydrophilicity, differ in their effectiveness as waste treatment agents. The specific relationship between methods and the particular crustacean species used in preparation of chitosan for wastewater treatment needs further examination. Use of bioremediation approaches, combined with immobilization of specific microorganisms on immobilized chitinous columns, is an extremely promising area of current research and actual plant operation.

Developments in world aquaculture, feed formulations, and role of carotenoids

Aquaculture is a rapidly growing global industry, comprising cultivation of various freshwater and marine species of finfish, shellfish, molluscs, and ornamental fish. By the year 2000, as much as 20% of the world production of fish will be based on aquaculture. Properly formulated feeds are a significant part of successful aquaculture. Carotenoids play a major role in culture of salmonids such as Atlantic salmon and rainbow trout. Various biological and nutritional roles for carotenoids in salmonids are documented along with the effect of biotic and abiotic factors on astaxanthin transport and retention and final flesh pigmentation. Relevant recent feeding results are presented. INTERNATIONAL DIMENSIONS OF AQUACULTURE Global moduct ion and growth Aquaculture, involving farming of a variety of freshwater and marine species of finfish, shellfish, molluscs, and ornamental fishes, is a rapidly growing global industry with a broad range of technological and managerial practices. In 1990 (ref. l), world aquaculture reached 15.3 million metric tons (MT), or 12.1 million MT, if aquatic plants were excluded. This is more than double that reported for the year 1975. Of this, approximately 50% was of freshwater origin, largely cyprinid species, while 6% was of marine origin. As much as 80% of aqua- culture production is centered in Asia, particularly in China and Southeast Asia. During the 1984-89 period, capture fisheries expanded only about 14%, while aquaculture rose nearly 70%. Furthermore, the total value of world aquaculture production averaged an annual increase of 15% during the 1984-90 period. Market demand for quality product has stimulated much of the growth in aquaculture, especially for salmonids and marine shrimp species. The total world aquatic harvest in 1991, including aquaculture, was about 96 million MT of which aquaculture comprised about 16% (ref. 2). Harvest limitations in global fisheries suggest that further growth in aquatic production will depend upon aquaculture. Projections are for global aquaculture output to exceed 20 million MT by the year 2000, comprising about 25% of the worlds seafood. Of cultured finfish, 85% are nonsarnivorous species, mostly cyprinids of various Chinese and Indian carp species. Almost half of the carnivorous species are salmonids, a ratio of about 50:50 salmon and trout. In the period 1986 to 1989, increases of 100-180% occurred in production of farmed Atlantic and Pacific salmon, while increases of 20-70% were recorded for common carp, tilapias, channel catfish, rainbow trout, and various species of marine shrimp, the latter comprising nearly 88% of crustacean aquaculture production. Global shrimp production alone in 1989 was over 530,000 MT, varying in volume and particular species with specific country. Successful cultivation of other marine finfish includes that of yellowtail, sea bass, sea bream, flatfish, grouper, and snapper. Numerous other marine and freshwater finfish are in various stages of evaluation for commercial aquaculture purposes. Salmonid broductim In 1991, the worldwide annual harvest of salmon was approximately 720,000 MT, of which 25- 30% were produced in a variety of aquaculture facilities and encloske designs. This includes such salmonid species as rainbow trout, Atlantic salmon, chinook salmon, and coho, pink, and chum salmon. The most spectacular growth has been with Atlantic salmon, notably in Norway

Characterization of volatile components of menhaden fish (brevoortia tyrannus) oil

Volatile odor components of winterized and undeodorized menhaden(Brevoortia tyrannus) oil were characterized by dynamic headspace concentration on a porous polymer trap, thermal desorption, cryogenic focusing, high resolution gas chromatography, mass spectrometry and chromatography-coupled descriptive odor evaluation. Many volatile odor components derived from lipid oxidation in the fish oil were identified. These included, among others, short-chain saturated and unsaturated aldehydes and ketones, as well as short-chain carboxylic acids. The former imparted greasy, oily, oxidized oil and green grassy or green plant-like odors, and the latter gave rather objectionable sweaty odors. Normal alkanes were detected as major volatiles without significant odors. The odor-significant volatile components may be used as specific flavor quality markers to determine deodorization efficiency on crude fish oil and to monitor flavor stability of purified oils. This combined analytical approach can be readily applied to the study of volatile components in other oils.

Purification and characterization of anionic trypsins from the hepatopancreas of crayfish, Procambarus clarkii

Abstract 1. 1. Four anionic trypsins, A, B, C, and D, were isolated from crayfish hepatopancreas, and punities were increased 56-, 100-, 87-, and 64-fold with approximately 2.4,8.1, 5.1, and 3.0% yield, respectively. 2. 2. The molecular weights of trypsin, A, B, C, and D were estimated to be 23.8, 27.9, 24.8 and 31.4 kDa, respectively, using Sephacryl S-200 gel filtration. 3. 3. Isolectric points and amino acid profiles of the four enzymes were similar to other trypsins from marine animals. 4. 4. Thermal stabilities were similar and all were unstable at acidic pH. 5. 5. Sensitivity to inhibotrs of these trypsins was similar to trypsin-like enzymes found in marine animals.

Enzymatic properties of anionic trypsins from the hepatopancreas of crayfish, Procambarus clarkii☆

Abstract Maximum amidolytic and esterolytic activities of crayfish hepatopancreatic trypsins occurred in a pH range of 7.5–8.5. Activity of trypsin A increased by addition of 0.5 mM of Ca 2+ ions; however, other trypsins were not affected by this concentration. Kinetic properties of crayfish trypsins toward esterolytic reaction were similar, but those for amidolytic reaction were different. Activation energies for esterolytic reaction were approximately 6.4–9.0 kcal/mole, while those for amidolytic reaction were between 5.9 and 6.9 kcal/mole.

A rapid quantitative method for determination of astaxanthin pigment concentration in oil extracts

Power models were developed to demonstrate relationships between absorption maxima (λmax) and specific extinction coefficients (E1cm1%) for the carotenoid astaxanthin and astacene in different oils and organic solvents. An accurate and rapid determination of concentration of astaxanthin-enriched oil can be achieved by using the predicted E1cm1% value based on absorption maxima in the visible light spectrum. Several vegetable or fish oils have been shown to be comparatively efficient in extracting astaxanthin pigment from crustacean waste in a pilot plant.

Rates of chitin degradation in an estuarine environment

In vitro chitin degradation rates in pure cultures and in mixed natural cultures have been determined and compared with those of other workers.In situ studies in the salt marsh shrimp nursery grounds along the southeastern Louisiana coast showed that chitin degradation was most rapid (118 mg d−1 g−1 chitin) when water temperature averaged 30‡C. Maximum degradation rates were noted at the water-sediment interface and when substrate particles were reduced in size (0.25 cm2). Of the several types of chitin tested, including treated and untreated, native chitin was most rapidly solubilized. Microbial populations on this substrate developed more rapidly, suggesting that chitin degradationin situ is a function of initial colonization. This is further supported by the observation that degradation rates were most rapid when total bacteria, chitinoclastic bacteria, and the ratio of chitinoclasts to total bacterial biomass (15.6 %) was greatest.

Claviceps Purpurea on Spartina in Coastal Marshes

The ergot fungus Claviceps purpurea was found on Spartina alterniflora throughout Gulf and Atlantic coastal marshes. Spartina patens and Spartina cynosuroides were also collected bearing sclerotia of C. purpurea. Observations on the intensity of infection are reported, with notably heavy infection apparent in regions of spoil deposits Conditions for germination of sclerotia are given along with some details of stromal morphology. Implications of C. purpurea in salt marsh ecosystems are discussed.

Microbiological and chitinoclastic activities associated with Penaeus setiferus

Analysis of microbiological and chitinase activities relative to the white shrimpPenaeus setiferus, and its chitinoclastic endosymbionts, have demonstrated the relevance of total chitinolytic processes in penaeid biology. Microorganisms may serve as a direct source of nutrients for the animal as well as in the elaboration of extracellularin situ chitinase enzymes. The enzyme produced by the predominant gut bacteria,Beneckea neptuna, is a moderately actively inducible chitinase while the shrimp has an indigenous constitutive chitinase and chitobiase system. Factors of temperature, pH, ion inhibition and reducing sugar ratios have been compared for the bacterial and animal enzymes. This dual enzyme system suggests that metabolic chitin transformation may play a vital role in crustacean metabolism.

Evaluation of Chemoreception by Penaeus vannamei under Experimental Conditions

Abstract A series of descriptors (perception, orientation, displacement or movement, arrival at feed, and feeding intensity) was developed to characterize the responses of Pacific white shrimp (Penaeus vannamei) to chemical feeding stimuli. Controlled laboratory trials established both requisite experimental system design and reproducible responses by shrimp, permitting quantification of behavioral patterns and feed preferences. Responses to pelleted feed with and without a coating of commercial chemoattractant demonstrated that the chemoattractant improved perception of the feed and shortened response times (by as much as 50%). The strength of shrimp feeding responses was positively correlated with the degree of prior starvation.