Isolation, antifungal activity, and structure elucidation of the glutarimide antibiotic, streptimidone, produced by Micromonospora coerulea.

The antibiotic Ao58A,which showed strong antifungal activity against some plant pathogenic fungi, was purified from the culture broth and mycelial mats of Micromonospora coerulea strain Ao58 using various chromatographic procedures. The molecular formula of the antibiotic Ao58A was deduced to be C(16)H(23)NO(4) (M + H, m/z 294.1707) by high-resolution FAB mass spectroscopy. Analyses of (1)H NMR, (13)C NMR, and 2D NMR spectral data revealed that the antibiotic Ao58A is the glutarimide antibiotic streptimidone, 4-(2-hydroxy-5, 7-dimethyl-4-oxo-6,8-nonadienyl)-2,6-piperidinedione. The antibiotic Ao58A was very effective in inhibiting growth of Phytophthora capsici,Didymella bryoniae, Magnaporthe grisea, and Botrytis cinerea in the range approximately 3-10 microg mL(-)(1) of MICs. In vivo evaluation of the antibiotic Ao58A under greenhouse condition showed strong control efficacies against the development of P. capsici, B. cinerea, and M. grisea on pepper, cucumber, and rice plants, respectively. The antibiotic Ao58A was equally as effective as metalaxyl, vinclozolin, and tricyclazole in the control of these plant diseases. However, it did not show any phytotoxicity on the plants even when treated with 500 microg mL(-)(1).     

Policosanol Contents and Composition of Grain Sorghum Kernels and Dried Distillers Grains

Grain sorghum can be a major source of policosanols, long‐chained alcohols, that have beneficial physiological activities. Sorghum dried distillers grains (DDG), a by‐product of ethanol production from grain sorghum, contain a large amount of policosanols. Content and composition of policosanols in long‐chained lipids extracted from grain sorghum kernels and DDG were determined. Long‐chained lipids were extracted using hot hexane or hot ethanol. The major components of the long‐chained lipids extracted from grain sorghum kernels, as determined using HPLC, were policosanols (37–44%), aldehydes (44–55%), and acids (4–5%). Long‐chained lipids from DDG contained 52% policosanols, 23% aldehydes, 6.4% acids, and 17% wax esters/steryl esters. Composition of policosanols in DDG matched the composition in grain sorghum kernels, as determined by gas chromatography, even though the content of policosanols in DDG was greater than the content in grain sorghum kernels. Policosonal composition ranges were 0–1% C22:0, 0–3% C24:0, 6–8% C26:0, 1% C27:0, 43–47% C28:0, 1–2% C29:0, 40–43% C30:0, and 1–4% C32:0.     

Egg hatching rate and fatty acid composition of Acartia bilobata (Calanoida,Copepoda) across cold storage durations

To investigate egg storage capacity of the copepod Acartia bilobata for aquaculture interest, we tested hatching success rate (HSR) of inclusive eggs (mixture of all egg types) after 4°C storage. The HSR peaked after 14 days storage when incubating at 28°C for 48 hr (85.8 ± 1.6%) and 72 hr (87.6 ± 0.9%), then gradually declined until 1 year (48 hr: 7 ± 0.6%; 72 hr: 19.4 ± 3.9%). Reallocation of fatty acid profile suggests that docosahexaenoic acid (DHA) is correlated with the HSR of A. bilobata eggs. Additionally, we investigated the HSR of diapausing eggs (unhatched eggs after 72 hr incubation of the inclusive eggs) after 4°C storage. Their HSR peaked after 14 days storage (48 hr:75.3 ± 3.5%; 72 hr:78.2 ± 2.1%), then gradually declined until 60 days (48 hr HSR:42.1 ± 2.3%; 72 hr HSR:53.0 ± 3.2%). Overall, we illustrated the hatchability of diapausing and quiescent eggs of A. bilobata after 4°C storage. The cold storage capacities were low (<60% HSR after 60 days), and it could be limited by the egg DHA content. Our findings provide implications for future studies aiming to improve cold storage techniques of tropical copepod eggs for aquaculture applications.     

Soybean meal and wheat flour,proper dietary protein sources for optimal growth of snail (<Emphasis Type="Italic">Semisulcospira coreana</Emphasis>)

A 10-week feeding experiment was conducted to determine the proper dietary protein source for optimal growth performance of juvenile snails, Semisulcospira coreana. Sixteen isonitrogenous (31% crude protein) and isocaloric (4.2 kcal/g DM) experimental diets (designated as FM, F-FM, SBM, F-SBM, WF, F-WF, SSM, F-SSM, SCR, F-SCR, UP, F-UP, FWP, F-FWP, MIX and F-MIX) were formulated to contain 41% fish meal, 42% fermented fish meal, 59% soybean meal, 55% fermented soybean meal, 55% wheat flour with 26% fish meal, 55% fermented wheat flour with 29% fish meal, 50% sesame seed meal with 10% fish meal, 50% fermented sesame seed meal with 11% fish meal, 55% soya-curd residue or fermented soya curd residue with 25% fish meal, 50% Undaria powder or fermented Undaria powder with 24% fish meal, 50% freshwater plant with 29% fish meal, 50% fermented freshwater plant with 28% fish meal, a mixture of 8% soybean meal, 10% wheat flour, 8% sesame seed meal, 8% soya-curd residue, 8% Undaria powder and 8% freshwater plant with 17% fish meal, and 50% the fermented mixture with 16% fish meal, respectively, as dietary protein sources. Juvenile snails (average weight, 32 ± 0.7 mg) were randomly distributed in forty-eight 25-L aquaria (16 L water each) in a flow-through system at a density of 130 snails per aquarium. Three replicate groups of snails were fed one of the experimental diets ad libitum once per day for 10 weeks. At the end of the feeding experiment, survival of snails was above 98% and not significantly different among the dietary treatments. The best final body weight was observed in snails fed the SBM and WF diets. There were no significant differences in final body weight of snails fed the F-SBM, WF, F-WF and MIX diets, but the value was higher than that of snails fed the FM, F-FM, FWP and F-FWP diets. The lowest value was observed in snails fed the SSM, F-SSM, SCR and F-SCR diets. Whole body protein and lipid contents of snails varied with dietary protein sources. Amino acid composition of whole body was altered by dietary protein sources. The results of the present study indicate that dietary protein sources significantly influence proximate and amino acid composition, and growth performance of snails. Fermentation with ferminpan instant brown yeast does not improve nutritional quality of the protein sources, and soybean meal and wheat flour in combination with fish meal could be potential protein sources in feeds for juvenile snails.     

Effect of dietary medicinal herbs on lipid metabolism and stress recovery in red sea bream <Emphasis Type="Italic">Pagrus major</Emphasis>

The effect of dietary medicinal herbs on lipid metabolism and stress recovery was investigated in red sea bream Pagrus major. Fish (mean body weight 24.0 ± 0.2 g) were fed on test fish meal diets supplemented with either Massa Medicata (Mm), Crataegi Fructus (Cf), Artemisia capillaries (Ac), or Cnidium officinale (Co), or with a mixture of the four herbs (HM) for 12 weeks. A control group was fed a diet without herbs in the same manner. A high survival rate was observed in the herbal diet groups. The final mean body weight, feed efficiency, protein efficiency ratio, and apparent protein and lipid retention in the Ac, Co, and HM groups were higher than those in the control and Mm groups. Final carcass, hepatic lipid and triglyceride contents, and plasma triglyceride and nonesterified fatty acid levels were lower in the Ac, Co, and HM groups compared to those of control and Mm groups. However, final hepatic phospholipid, plasma phospholipid, and high density lipoprotein cholesterol levels were higher in the Ac, Co, and HM diets groups than in the control and Mm groups. The Cf, Co, Ac, and HM groups showed faster recovery time in the 2-phenoxyethanol anesthesia test and a higher recovery rate in the 10-min air exposure test than those of the control and Mm groups. Moreover, the Cf, Ac, Co, and HM diet groups had a significantly lower plasma cortisol level than the control and Mm diet group, but the glucose level in the herbal diet groups was higher than that in the control group after a 1-h air exposure. These results indicate that the addition of medicinal herbs to the fish diet improved lipid utilization and stress recovery in red sea bream.     

Antibacterial Meroterpenoids,Merochlorins G–J from the Marine Bacterium Streptomyces sp.

Four new chlorinated meroterpenoids, merochlorins G−J (1−4), and 10, a dihydronaphthalenedione precursor, along with known merochlorins A (5) and C−F (6−9), were obtained from cultivation of the bacterium strain Streptomyces sp. CNH-189, which was isolated from marine sediment. The planar structures of compounds 1−4 and 10 were elucidated by interpretation of MS, UV, and NMR spectroscopic data. The relative configurations of compounds 1−4 were determined via analysis of nuclear Overhauser effect (NOE) spectroscopic data, after which their absolute configurations were established by comparing the experimental electronic circular dichroism (ECD) spectra of compounds 1−4 to those of previously reported possible enantiomer models and DP4 calculations. Compound 3 displayed strong antibacterial activities against Bacillus subtilis, Kocuria rhizophila, and Staphylococcus aureus, with MIC values of 1, 2, and 2 μg/mL, respectively, whereas compound 1 exhibited weak antibacterial effects on these three strains, with a 16−32 μg/mL MIC value range.     

Combined effect of biochar and soil moisture on soil chemical properties and microbial community composition in microplastic-contaminated agricultural soil

Accumulation of microplastics (MPs) in agricultural environments has caused growing concern in recent years because of its detrimental impacts on soil quality, crop productivity and ecosystem function. This study was conducted to assess the impact of biochar on soil chemical and microbial properties in a MP-contaminated soil under two moisture regimes. Soil was contaminated with 1% (w/w) of low-density polyethylene MPs. Four types of standard biochar, that is, oil seed rape (OSR) biochar produced at 550°C (OSR 550) and 700°C (OSR 700) and soft wood pellet (SWP) biochar produced at 550°C (SWP 550) and 700°C (SWP 700), were applied at a rate of 5% (w/w). The control was maintained without MP addition. The samples were incubated in soil with two moisture regimes, that is, at 30% and 70% of the water holding capacity, and the soil chemical and microbiological properties were assessed after 100 days of incubation. OSR biochar application significantly increased soil pH (8.53–8.81) and electrical conductivity (0.51–0.58 dS/m) in both moisture regimes. The effect of biochar application on soil enzyme activity and microbial community composition did not show a clear trend. However, SWP 700 biochar improved soil enzyme activity compared with that of the control and improved bacterial diversity and evenness compared with those of other biochars, which was attributed to the high surface area available for microbial colonization. Low soil moisture content significantly reduced enzyme activity and bacterial richness even with biochar amendment, except for SWP 550 biochar. This study implies the suitability of biochar for improvement of soil quality in MP contaminated soil under both moisture regimes. However, further long-term studies are needed to get a clear understanding on the impact of different types of biochar on MP-contaminated soil.     

Determining Wheat Dough Mixing Characteristics from Power Consumption Profile of a Conventional Mixer

A Hobart mixer with a pin‐type attachment was used to mix soft wheat flour dough. Power consumption profiles were measured continuously during mixing for 20 min using a current transducer and a data logging system. Experimental variables were quantity of flour (500, 1,000, and 1,500 g of dry wheat flour), water content (43, 45, and 47%, wb), and mixer speed setting (low, medium, and high). The power consumption profiles were evaluated by moving average and spectral analysis. Peaks in the power consumption profiles were located to determine the optimal mixing time. The optimal mixing times were then compared with storage and viscous moduli measured using a dynamic rheometer to assure the maximum strength of wheat dough at the optimal mixing time. Tolerance was determined using the signal amplitude and phase angle data from spectral analysis. Optimal mixing times of various doughs at medium speed ranged from 510 to 850 sec; low and high flour quantities required longer mixing times than medium quantity of flour. The optimal mixing time increased when the moisture content was lowered. Tolerance was affected by mixing speed and moisture content of flour