Thermal conversion of elephant grass (Pennisetum purpureum Schum) to bio-gas, bio-oil and charcoal

Elephant grass is an abundant, fast growing plant with significant potential as a renewable energy source and for conversion to higher calorific value fuels. This work investigates thermal conversion of elephant grass to bio-gas, bio-oil and charcoal under two heating rates of 10 and 50 degrees C/min. The energy required to pyrolyse elephant grass was evaluated using computer aided thermal analysis technique, while composition of the resultant bio-gas and bio-oil products were monitored with gas chromatographic and mass spectroscopic techniques. At 500 degrees C, the bio-gas compounds consisted primarily of CO(2) and CO with small amounts of methane and higher hydrocarbon compounds. The heat of combustion of the bio-gas compounds was estimated to be 3.7-7.4 times higher than the heat required to pyrolyse elephant grass under both heating rates, which confirms that the pyrolysis process can be self-maintained. Faster heating rate was found to increase the amount of liquid products by 10%, while charcoal yields remained almost the same at 30%. The bio-oil mainly consisted of organic acids, phthalate esters, benzene compounds and amides. The amount of organic acids and benzene compounds were significantly reduced at 50 degrees C/min, while the yields of phthalate esters and naphthalene compounds increased. The difference in bio-oil composition with increased heating rate is believed to be associated with the reduction of the secondary reactions of pyrolysis, which are more pronounced under lower heating rate.     

Use of elephant grass (Pennisetum purpureum) acid hydrolysate for microbial oil production by Trichosporon cutaneum

Elephant grass (Pennisetum purpureum) dilute acid hydrolysate contains 34.6?g/L total sugars. The potential of lipid production by oleaginous yeast Trichosporon cutaneum grown on elephant grass acid hydrolysate was investigated for the first time. During the fermentation process on the elephant grass acid hydrolysate, glucose, xylose, and arabinose could be well utilized as carbon sources by T. cutaneum. Interestingly, xylose was almost no use before glucose was consumed completely. This illustrated that simultaneous saccharification of xylose and glucose by T. cutaneum did not occur on elephant grass acid hydrolysate. The highest biomass, lipid content, lipid yield, and lipid coefficient of T. cutaneum were measured after the sixth day of fermentation and were 22.76?g/L, 24.0%, 5.46?g/L, and 16.1%, respectively. Therefore, elephant grass is a promising raw material for microbial oil production by T. cutaneum.     

Biochemical and molecular analysis of plants derived from embryogenic tissue cultures of napier grass (Pennisetum purpureum K. Schum)

Summary We have investigated the extent of biochemical and molecular variation in 63 plants of napier grass (Pennisetum purpureum K. Schum.) regenerated from 3- to 24-week-old embryogenic callus cultures. The calli were derived from cultured basal segments of young leaves and immature inflorescences obtained from a single fieldgrown donor plant. The entire population was analyzed for the activity of 14 isozyme systems, but no qualitative variation was found at any of the loci examined. Similarly, no restriction fragment length polymorphisms (RFLPs) were detected in the mitochondrial, plastid and nuclear genomes in a representative sample of regenerated plants. Our results confirm earlier reports of the genetic uniformity of plants derived from somatic embryos and highlight their value both for clonal propagation and for genetic transformation.     

Isolation and identification of the predominant lactobacilli in elephant grass (Pennisetum purpureum) and Guatemala grass (Trypsacum laxum) silage from Bambui,Cameroon

Summary The predominant lactobacilli in silages made from elephant grass and Guatemala grass were strains ofLactobacillus casei. These were characterized by traditional taxonomic methods.

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Resumen Los lactobacilos predominantes en ensilados de pasto elefante y pasto guatemala eran cepas deLactobacilus casei. Estas cepas se caracterizaron mediante métodos taxonómicos tradicionales.

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Résumé Les lactobacilles prédominant dans les ensilages d'herbe à éléphant et d'herbe du Guatemala sont des souches deLactobacillus casei. Ces souches ont été caractérisées par les méthods taxonomiques traditionelles.

     

Analysis of Genetic Diversity in Napier Grass (Pennisetum purpureum Schum) as Detected by RAPD and ISSR Markers

Randomly Amplified Polymorphic DNA (RAPD) and Inter-Simple Sequence Repeat (ISSR) markers were used to detect the DNA polymorphism among thirty Napier grass collections of wide geographical distribution. A total of 20 RAPD and 10 ISSR primers were used in this study. RAPD analysis produced 222 fragments of which, 195 were polymorphic with an average of 9.75 polymorphic fragments per primer. The ten ISSR primers produced a total of 98 fragments out of which 88 were polymorphic accounting for 89.8%. The Mantel test between two similarity matrices of the markers revealed a low correlation (r = 0.33) indicating low correspondence between polymorphism brought out by the two marker systems. The UPGMA clustering of genotypes eventhough was not similar when RAPD and ISSR derived dendrograms were compared, but showed a greater correspondence with geographical identity in both the marker systems employed. This correspondence was also evident when data from both the RAPD and ISSR markers were combined. The implications on collection and breeding of this important forage grass had been discussed.     

Effect of a controlled-release urea supplement on rumen fermentation in sheep fed a diet of sugar cane tops (Saccharum officinarum), corn stubble (Zea mays) and King grass (Pennisetum purpureum)

Four cannulated sheep were used to study ruminal fermentation of a diet consisting of 60% sugar cane tops (Saccharum officinarum), 30% corn stubble (Zea mays), 10% King grass (Pennisetum purpureum) and 0% (control), 10, 20 or 30% controlled-release urea supplement (CRUS) (diets 1, 2, 3 and 4, respectively). Average ruminal pH did not differ among diets (P>0.05), but during the first 6 h of sampling tended to be higher for CRUS diets. Ammonia concentrations were higher (P<0.01) in all treatments over controls, indicating microbial protein generation. Acetic acid production (mM/1) decreased (P<0.05), propionic acid increased (P<0.05), while butyric acid production did not differ among CRUS diets and controls (P>0.05). Total amounts of ruminal VFA were lowest (P<0.01) in controls, while CRUS diets produced more of these energy sources. Supplementation of the high fiber diets with 10, 20 or 30% CRUS increasingly improved rumen fermentation, ammonia supply and VFA production. The results show that low quality forages (up to 70% DMI) can be used efficiently by sheep when conditions for ruminal microorganism are improved with a controlled-release urea supplement.     

Influence of different chemical pretreatments of elephant grass (<Emphasis Type="Italic">Pennisetum purpureum</Emphasis>, Schum.) used as a substrate for cellulase and xylanase production in submerged cultivation

This study evaluated the potential use of elephant grass biomass, a highly productive species, for cellulase and xylanase production by the cellulolytic mutant Penicillium echinulatum 9A02S1 in submerged cultivation, using untreated biomass, biomass pretreated with different concentrations of NaOH, H₂SO₄ or NH₄OH, or biomass pretreated with H₂O at 121 °C. For filter paper activity, all cultivation carried out with pretreated elephant grass under the evaluated conditions showed superior activity when compared with the control (untreated elephant grass). The activities of endoglucanases and β-glucosidases were higher in the cultivation prepared from pretreated samples than the control made with cellulose (Celuflok^®). Without pretreatment, elephant grass can be used for xylanase production, enabling similar activities to those obtained in the cultivation with cellulose, reducing the enzyme production cost. These results indicate that the pretreatment of elephant grass, especially when pretreated with H₂SO₄, may be used as a partial or total replacement for cellulose to cellulase production, and untreated elephant grass may be used for xylanase production.     

花前渍水预处理对花后渍水逆境下扬麦9号籽粒产量和品质的影响

以扬麦9号为材料,研究花前渍水预处理对花后渍水逆境下小麦籽粒产量和品质的影响。结果表明,与未进行渍水预处理相比,花前渍水预处理提高了小麦植株对花后渍害的抗性,生物产量、收获指数和千粒重显著提高,进而显著提高了籽粒产量;花前渍水预处理显著提高花后氮素积累量及其对籽粒氮素的贡献率,降低了花前贮藏氮素运转量及其对籽粒氮素的贡献率,进而引起籽粒球蛋白含量提高,但显著降低了清蛋白、醇溶蛋白、谷蛋白和全蛋白质含量、以及干湿面筋含量和沉降值;花前渍水预处理还提高了籽粒直链淀粉和总淀粉含量和降落值,降低了支/直链淀粉比,显著提高了面粉峰值粘度、低谷粘度、崩解值、最终粘度、回冷值和峰值时间,但对糊化温度无显著影响。     

A lack of correlation between the biological activity and rate of metabolism of ent-(3H)-17-kaurenoic acid by seedlings of dwarf rice cv. Tan-ginbozu

Significant leaf sheath elongation occurred within 24 hr afterapplication of 10 µg (0.67, µCi) of ent-(³H)-17-kaurenoicacid (KA) to individual seedlings of dwarf rice cv. Tan-ginbozu,but this growth was unaccompanied by production of significantlevels of radioactivity in more polar, acidic, ethyl acetate-solublemetabolites of (³H)-KA. However modest levels of radioactivityappeared in the highly water-soluble fraction by hour 24, subsequentto the most rapid phase of KA-induced growth. Growth continuedand by hour 48 was accompanied by the appearance of small amountsof radioactivity in polar, acidic products. It would appearthat KA per se, and not its metabolic products, may be responsiblefor the leaf sheath elongation noted at hour 24. On the speculation that it might be a metabolite of KA, gibberellinA₁₄ (GA₁₄) was applied simultaneously with (³H)-KA to individualrice seedlings. Several changes in the metabolism of ³H-KA inthe presence of GA₁₄ were noted, and GA₁₄ antagonized the KA-inducedsheath elongation. ¹Present address: Botany Department, Rhodes University, Grahamstown,6140, South Africa. ²Present address: Crop Science Department, University of Saskatchewan,Saskatoon, Sask. S7N OWO, Canada. (Received May 12, 1975; )     

Insulin-like growth factor-1 and growth hormone (GH) levels in canine cerebrospinal fluid are unaffected by GH or GH secretagogue (MK-0677) administration.

Elevation in circulating GH levels results in a dose-related increase in serum insulin-like growth factor-1 (IGF-1) levels in dogs. However, it is not known whether elevations in systemic IGF-1 and GH levels contribute to the cerebrospinal fluid (CSF) levels of these hormones. Therefore, a study was designed in dogs to determine if elevated circulating GH levels was a result of a GH secretagogue (MK-0677) or if exogenous GH administration resulted in increased IGF-1 and GH levels in the CSF of dogs. A total of 12 normal, young adult male dogs were randomized to three treatment groups (4 dogs/group) based on body weight. There were 4 vehicle control dogs. A group of 4 dogs were dosed orally with MK-0677 (5 mg/kg/day) dissolved in deionized water. A third group of 4 dogs received subcutaneous injections of porcine GH (pGH) at a dose of 0.1 IU/kg/day. From all dogs, blood and CSF samples were collected prior to the initiation of treatment and on days 7 and 15 of treatment. All samples were assayed using a validated radioimmunoassay. Administration of MK-0677 or pGH resulted in a statistically significant (P < or = 0.05) increased body weight gain and increased serum IGF-1 and GH levels. In contrast, administration of MK-0677 resulted in no significant (P > 0.05) increase in CSF IGF-1 or GH levels on days 7 or 15 of the study. The CSF IGF-1 values ranged from 1.2 to 2.0 ng/ml with minimal variation among three separate samples taken during the course of the study from each dog. Similarly, the CSF GH levels were very low (< 0.98 ng/ml to 2.4 ng/ml) in all dogs irrespective of treatment group. This study has demonstrated that there is no correlation between the circulating levels of IGF-1 or GH and the levels of these hormones in the CSF of normal dogs. An approximately 100-fold difference between serum and CSF IGF-1 levels in vehicle control dogs suggest that there is a blood-brain barrier for the circulating IGF-1. Similarly, failure to see an elevation in CSF GH levels despite increases in serum GH levels shows that there is a blood-brain barrier for GH in normal dogs. These results suggest that the likely source of GH and IGF-1 in the CSF of dogs is from the CNS.