Potential of giant reed (Arundo donax L. ) for second generation ethanol production

Background The production of second generation ethanol from lignocellulosic biomasses that have not had their potential fully explored as feedstock is of great importance. Arundo donax is one these biomasses. It is a promising grassy plant to be used as a renewable resource for the production of fuels and chemicals, because of its fast growth rate, ability to grow in different soil types and climatic conditions. The present study evaluated its use as feedstock for the production of second generation ethanol. Results Initially its chemical characterization was carried out, and a protocol for fractioning the biomass through diluted acid pretreatment followed by alkaline pretreatment was developed, providing a solid fraction which was undergone to enzymatic hydrolysis reaching 42 g/L of glucose, obtained in 30 h of enzymatic hydrolysis. This partially delignified material was subjected to a simultaneous saccharification and fermentation (SSF) process, resulting in an ethanol concentration of 39 g/L at 70 h. Conclusions The fermentability of the pretreated biomass was performed successfully through the conception of simultaneous saccharification and fermentation resulting in approximately 75 L of ethanol per ton of cellulose.

Selective isolation of Actinomycetes from mangrove sediment of Tanjung Lumpur, Kuantan, Malaysia

Aims: Mangroves of Tanjung Lumpur, Kuantan, Pahang is considered as a relatively underexplored resource of actinomycetes. Based on the above perspective, a study was conducted on mangrove sediments of Tanjung Lumpur, Kuantan to isolate potential actinomycetes using several pretreatments and various selective media. Methodology and results: Sediments from five different sites at Tanjung Lumpur mangrove were collected and selectively pre-treated. The pretreated sediments were diluted and plated onto eight different selective media. A total of 172 potential actinomycetes were isolated from all the media. Antimicrobial activities of 61 selected strains were checked against 8 test microorganisms using cross streak method. Pretreatment of wet heat with seawater was the most effective method for the isolation of actinomycetes as it yielded a maximum of 105 actinomycete isolates and IM7 was the most suitable medium for actinomycete isolation with highest percentage of recovery (31 %). Forty three isolates (70.5 %) showed antimicrobial activities against one or more test microorganisms. Isolates IIUM B21 and IIUM B31 showed antimicrobial activity against all test microorganisms. Seven isolates showed antifungal activity as they inhibited only C. albicans. Ten isolates were randomly selected for identification based on partial sequences of 16S rRNA gene. Six isolates were found belong to the genus Streptomyces, two isolates belong to the genus Micromonospora and two isolates were identified as Rhodococcus spp. Conclusion, significance and impact of study: These findings revealed the potential of mangrove sediment of Tanjung Lumpur as an important source of actinomycetes with biosynthetic capabilities which might be beneficial to pharmaceutical industries.

Shear bond strength of a new self-adhering flowable composite resin for lithium disilicate-reinforced CAD/CAM ceramic material

PURPOSE: The purpose of this study was to evaluate and compare the effects of different surface pretreatment techniques on the surface roughness and shear bond strength of a new self-adhering flowable composite resin for use with lithium disilicate-reinforced CAD/CAM ceramic material. MATERIALS AND METHODS: A total of one hundred thirty lithium disilicate CAD/CAM ceramic plates with dimensions of 6 mm x 4 mm and 3 mm thick were prepared. Specimens were then assigned into five groups (n=26) as follows: untreated control, coating with 30 microm silica oxide particles (Cojet(TM) Sand), 9.6% hydrofluoric acid etching, Er:YAG laser irradiation, and grinding with a high-speed fine diamond bur. A self-adhering flowable composite resin (Vertise Flow) was applied onto the pre-treated ceramic plates using the Ultradent shear bond Teflon mold system. Surface roughness was measured by atomic force microscopy. Shear bond strength test were performed using a universal testing machine at a crosshead speed of 1 mm/min. Surface roughness data were analyzed by one-way ANOVA and the Tukey HSD tests. Shear bond strength test values were analyzed by Kruskal-Wallis and Mann-Whitney U tests at alpha=.05. RESULTS: Hydrofluoric acid etching and grinding with high-speed fine diamond bur produced significantly higher surface roughness than the other pretreatment groups (P<.05). Hydrofluoric acid etching and silica coating yielded the highest shear bond strength values (P<.001). CONCLUSION: Self-adhering flowable composite resin used as repair composite resin exhibited very low bond strength irrespective of the surface pretreatments used.