Synergetic effects of cell immobilization in polyurethane foam and use of thermotolerant strain on degradation of mixed hydrocarbon substrate by Prototheca zopfii

ABSTRACT:   The synergetic effects of an immobilized cell system in an oleophilic polyurethane foam (PUF) and use of a thermotolerant strain on degradation of hydrocarbons by colorless green microalga Prototheca zopfii are reported. Two strains of P. zopfii , i.e. thermotolerant RND16 and non-thermotolerant ATCC30253, were immobilized in PUF to compare their abilities to biodegrade a mixed hydrocarbon substrate (MHS) containing aliphatic and polycyclic aromatic hydrocarbons (PAHs), as a function of temperature. The thermotolerant strain RND16 degraded MHS at 35°C, while ATCC30253 did not degrade hydrocarbons at temperatures higher than 30°C. Immobilization of P. zopfii in PUF resulted in shortened lag for growth-associated biodegradation of n -alkanes in MHS, the effect of which was most significant in cultures of RND16 at 25°C. Nevertheless, the decrease in the amount of degraded PAHs was caused by PUF immobilization and the level of this decrease was marked in the cultures of RND16, in which rate and extent of n -alkane degradation were higher than for ATCC30253.     

Taste-active components in a Vietnamese fish sauce

Taste-active components were determined for a typical first-grade Vietnamese fish sauce Nuoc mam , of which total content of extractive compounds reached as high as 20 g/ 100 mL. A complete synthetic extract prepared from 35 compounds according to the analytical data reproduced almost satisfactorily the taste of the original fish sauce. From the synthetic extract, 11 compounds were identified to be the taste-active components by a series of omission and addition tests. The components consisted of glutamic and aspartic acids, threonine, alanine, valine, histidine, proline, tyrosine, cystine, methionine, and pyroglutamic acid. The most effective compound for recreating the characteristic flavor of fish sauce was glutamic acid, followed by pyroglutamic acid and alanine. Many of these components contribute to umami, sweetness, and overall taste of fish sauce. Even though the simplified 11-component extract reproduced the taste of fish sauce, the taste strength was weaker than that of the complete synthetic extract or fish sauce itself.     

Maternal and genetic effects on individual variation during early development in Japanese flounder <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis>

ABSTRACT:   To investigate the changes in maternal effects during early development in Japanese flounder Paralichthys olivaceus , four-by-four factorial mating by artificial fertilization was performed to produce 16 families. Larvae and juveniles of each family were reared under common environmental conditions until completion of metamorphosis. The magnitude of maternal effects was estimated as the differences between sire and dam variance. Maternal effects were highest at hatching, and then disappeared at 30 days after hatching. During early development, larval size at hatching was largely affected by egg size, but this effect decreased as larvae grew. Estimated mean heritability during early development was nearly constant (0.14 ± 0.06 for total length and 0.10 ± 0.05 for body depth). Therefore, it is suggested that early development in Japanese flounder is affected by both maternal effect and genetic factors.     

Balancing protein ingredients in carp feeds to limit dischargeof phosphorus and nitrogen into water bodies

ABSTRACT:   Through a series of experiments, it has been demonstrated successfullythat an appropriate choice of ingredients is primary for achievinga reduction in phosphorus (P) and nitrogen (N) loading from carpculture. In this final study, four multi-ingredient diets were examined.In addition to the basal ingredients (fish meal 15%, corngluten meal 8%, defatted soybean meal 10%, blood meal3–5%), three of the test diets (PF, MM, and SP)contained 6% each of either poultry feather meal, meatmeal or soy protein concentrate, respectively, and the fourth diet(PMS) had each of the three aforementioned ingredients includedat 3%. These diets had crude protein < 35%,digestible energy > 3.5 kcal/g,available P between 0.65 and 0.66% and total P rangingfrom 1.26 to 1.36%. The diets were fed to juvenile carpduring a 12-week feeding trial. The highest growth was obtained forfish fed the MM diet. The absorption and retention rates of P werehigher for the PF diet, whereas these values for N did not showtreatment-related differences. The total discharges per ton fish productionwere estimated to range between 7.8 and 9.2 kg for P andbetween 39.1 and 40.7 kg for N. These were lower than thefigures for Lake Kasumigaura, a main carp culture site, indicatingthat proper balancing of protein ingredients aids in efficientlylowering emissions from aquaculture.     

Feeding habits of Pacific pomfret Brama japonica inthe transition zone of the central North Pacific

ABSTRACT:   We examined the diets of three size groups of the Pacific pomfret Bramajaponica collected in April and May 2000 in the transition zoneof the central North Pacific. Amphipods, cephalopods and fish werethree of the most common prey groups of pomfret. Of the three size groups,small pomfret (11.0–19.9 cm standard length (SL))preyed mainly on amphipods and occasionally on cephalopods (mainlytransitional species Onychoteuthis borealijaponica ) and fish.(These prey amphipods and fish could not be identified to lowertaxonomic levels because they were too digested.) Medium and largepomfret (20.0–30.9 and 31.0–40.9 cm SL,respectively) preyed mainly on cephalopods (mainly O. borealijaponica ,but also on two subarctic species, namely Berryteuthis anonychus and Gonatopsisborealis ), suggesting that these cephalopod species ensure energyfor the northward migration of these two size groups in the transitionzone in the spring. The next most common prey for medium pomfretwas amphipods (mainly subtropical species Phronima sedentaria and Platyscelusovoides ), followed by fish (mainly Bathylagus sp.). However,in the case of large pomfret, fish (mainly Paralepididae sp. 'A')were the next most common prey, followed by amphipods (mainly P.sedentaria and P. ovoides ), indicating that the importanceof fish as prey increases with growth for medium and large pomfret.     

A laboratory-based assessment of phosphorus and nitrogen loading from currently available commercial carp feeds

ABSTRACT: To clarify the total phosphorus (P) and nitrogen (N) loading from carp culture, five commercial diets were selected from a major location in Japan, Lake Kasumigaura, for a 12-week feeding trial. These diets were prepared as per the 'Kasumigaura Feed Standard' (crude protein < 35% and digestible energy > 3.5kcal/g), and total P ranged from 1.4% to 2.0%. However, for most of the diets the P available was lower than the requirement level. A control diet was formulated with 25% fishmeal to comply with that standard and contain adequate available P. Duplicate groups of juvenile carp were fed the aforementioned diets to satiation, three times a day, six days a week throughout the trial. Growth performance was significantly higher for the control group and values of P absorption (20.4–47.0%) and retention (14.0–36.3%) varied widely among the groups. Consequently, the total P loading (kg/t production) values based on retention fluctuated from 14.8 to 26.4 among the commercial diet groups compared with the low level of 8.5 for the control group. Similarly, the total N loading (kg/t production) values varied from 30.9 to 86.0 and was lowest for the control group. A higher whole body lipid and lower bone P and Ca confirmed the deficiency of the dietary available P in commercial diets. Better growth and comparatively less P and N loading rates were observed in the diet that had sufficient available P, not to mention that the control diet ranked best. It was concluded that an inadequacy of available P among the commercial diets affects the growth of carp and produces high P and N loading into the water. Therefore, if the commercial diets do not supply adequate levels of available P to carp, growth is negatively affected and may result in greater waste loading.     

Vertical Distribution of Physico-Chemical Properties and Number of Sulfur-Oxidizing Bacteria in the Buried Layer of Soil Profiles with Marine-Reduced Sulfur Compounds

We observed the presence of reduced sulfur compounds in the buried soil layer of a paddy field on Sado Island, Niigata Prefecture. We sampled the paddy field soil from 0 to 300 cm depth and analyzed the physico-chemical properties of the soil and the numbers of sulfur-oxidizing bacteria and iron-oxidizing bacteria in order to elucidate both the sulfur-oxidizing mechanism and the function of sulfur-oxidizing bacteria in the subsoil. Based on the physico-chemical properties of the soil, layers 4 and 5, which were located below 1 m in depth, were found to be potential acid sulfate soils and to be under semi-anaerobic conditions. However, the concentrations of water-soluble sulfate ions in layers 4 and 5 (88.2 to 444 mg S kg⁻¹) were higher than those in layers 1 and 3 (16.1 and 8.29 mg S kg⁻¹, respectively) and a significant number of sulfur-oxidizing bacteria (10^2–6 MPN g⁻¹) was detected in layer 4. These results suggested that the oxidation of reduced sulfur compounds by sulfur-oxidizing bacteria had occurred in layer 4. Since no iron-oxidizing bacteria were detected in any layers, and it was reported that sulfur-oxidizing bacteria such as Acidithiobacillus thiooxidans could not oxidize pyrite directly, it was considered that the oxidation of the reduced sulfur compounds in layer 4 occurred through the following processes. At first, reduced sulfur compounds such as pyrite were oxidized chemically by ferric ions to intermediary sulfur compounds such as thiosulfate ions. Subsequently, sulfur-oxidizing bacteria in layer 4 oxidized these intermediary sulfur compounds to sulfate ions. However, it was considered that the oxidation rate of the reduced sulfur compounds in layer 4 was far slower than would occur under aerobic conditions.     

Isolation and characterization of the interspecific fusants from Streptomycetes obtained using a liquid regeneration method

ABSTRACT: Protoplast fusion between different species of Streptomyces was performed using a liquid regeneration method developed for a rapid and simple preparation of the fusants. Consequently, new clones, which could not be obtained using the conventional agar regeneration method, were obtained. In the crosses between S. griseus and S. durhamensis , and between S. californicus and S. catenulae , eight and two recombinants, respectively, were obtained using the liquid regeneration method. Conversely, in the case of crosses between S. ornatus and S. catenulae , and between S. ornatus and S. vendargensis , seven recombinants each were obtained using only the agar method. The physiological characteristics, such as the assimilation of carbohydrate and antibiotic resistance, of these fusants differed considerably from those of their parental strains. Using the proposed liquid regeneration method, a simpler and quicker procedure for protoplast fusion is described.     

4-Nitro-3-phenylphenol has both androgenic and anti-androgenic-like effects in rats

To investigate the effect of endocrine disruption of 4-nitro-3-phenylphenol (PNMPP) on immature male Wistar-Imamichi rats, the rat pituitary was exposed to PNMPP (10^–5–10^–9 M) for 24 h with or without gonadotropin-releasing hormone (GnRH) in experiment I. In addition, the Leydig cells (10^–5–10^–9 M) were exposed to PNMPP for 24 h with or without human chronic gonadotropin (hCG) in experiment II. Our results showed that the PNMPP at 10^–5–10^–7 M suppressed follicle-stimulating hormone (FSH) and luteinizing hormone (LH) productions from GnRH-stimulated pituitary cells. At the same time, PNMPP 10^–5–10^–7 M induced an increase in testosterone production from the Leydig cells treated with or without hCG. Based on our results, it can be concluded that that PNMPP might have both androgen agonist action by decreasing FSH and LH production in the pituitary and anti-androgenic action by increasing testosterone production in the Leydig cell.