Biogas is a renewable fuel source of methane (CH4), and its utilization as a natural gas substitute or transport fuel has received much interest. However, apart from CH4, biogas also contains carbon dioxide (CO2) which is noncombustible, thus reducing the biogas heating value. Therefore, upgrading biogas by removing CO2 is needed for most biogas applications. In this study, an amine-functionalized adsorbent for CO2 capture from biogas was developed. Mesoporous MgO was synthesized and functionalized with different tetraethylenepentamine (TEPA) loadings by wet impregnation technique. The prepared adsorbents (MgO-TEPA) were characterized by X-ray diffraction (XRD) and N2 adsorption-desorption. The CO2 adsorption performance of the prepared MgO-TEPA was tested using simulated biogas as feed gas stream. The results show that the CO2 adsorption capacities of the adsorbents increase with increasing TEPA loading. The optimum TEPA loading is 40 wt.%, which gives the highest CO2 adsorption capacity of 4.98 mmol/g. A further increase in TEPA loading to 50 wt.% significantly reduces the CO2 adsorption capacity. Furthermore, the stability and regenerability of the adsorbent with 40% TEPA loading (MgO-TEPA-40) were studied by performing ten adsorption-desorption cycles under simulated biogas and real biogas conditions. After ten adsorption-desorption cycles, MgO-TEPA-40 shows slight decreases of only 5.42 and 5.75% of CO2 adsorption capacity for the simulated biogas and biogas, respectively. The results demonstrate that MgO-TEPA-40 possesses good stability and regenerability which are important for the potential application of this amine-based adsorbent.

This is the first report to present a full-length cDNA (designated HbPR-1) encoding a putative basic HbPR-1 protein from rubber tree (Hevea brasiliensis) treated with salicylic acid. It was characterized and also expressed in Nicotiana benthamiana using Agrobacterium-mediated transient gene expression system in order to investigate the role of HbPR-1 gene in rubber tree against its oomycete pathogen Phytopthora palmivora and to produce recombinant HbPR-1 protein for microbial inhibition test. The HbPR-1 cDNA was 647 bp long and contained an open reading frame of 492 nucleotides encoding 163 amino acid residues with a predicted molecular mass of 17,681 Da and an isoelectric point (pI) of 8.56, demonstrating that HbPR-1 protein belongs to the basic PR-1 type. The predicted 3D structure of HbPR-1 was composed of four α-helices, three β-sheets, seven strands, and one junction loop. Expression and purification of recombinant HbPR-1 protein were successful using Agrobacterium-mediated transient expression and one-step of affinity chromatography. Heterologous expression of HbPR-1 in N. benthamiana reduced necrosis areas which were inoculated with P. palmivora zoospores, indicating that the expressed HbPR-1 protein played an important role in plant resistance to pathogens. The purified recombinant HbPR-1 protein was found to inhibit 64% of P. palmivora zoospore germination on a water agar plate compared with control, suggesting that it was an antimicrobial protein against P. palmivora.

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Aims: This study aimed to use palm oil mill effluent (POME) as a renewable resource for the production of antifungal compounds by Streptomyces philanthi RM-1-138 against Ganoderma boninense, Ceratocystis paradoxa and Curvularia oryzae. Methods and results:The efficacy of antifungal compounds RM-1-138 against the three strains of fungal oil palm pathogen was evaluated both in vitro and on oil palm leaf segments. In vitro studies using confrontation tests on glucose yeast-malt extract (GYM) agar plates indicated that the strain RM-1-138 inhibited the growth of all three fungal pathogenic strains. The antifungal compounds produced in the GYM medium exhibited significantly higher inhibition (79%-100%) against the three fungal pathogens than using the diluted POME (50%) medium (80%-83% inhibition). The optimum condition for the production of antifungal compounds from the strain RM-1-138 was as following: POME of 47,966 mg L −1 chemical oxygen demand (COD), the initial pH at 7.0 and supplemented with yeast extract (0.4%). Meanwhile, severe morphological and internal abnormalities in C. oryzae hyphae were observed under a scanning electron microscope and transmission electron microscope. In vivo experiment on oil palm leaf segments indicated that the efficacy of the antifungal compounds RM-1-138 (DSI = 1.3) were not significantly difference in the suppression of Curvularia leaf spot compared with the two commercial chemical fungicides of mancozeb ® (DSI = 1.0) and tetraconazole ® (DSI = 1.3). Conclusions:Antifungal compounds produced by S. philanthi RM-1-138 grown in POME have the potential to inhibit fungal pathogens. Significance and impact of the study:The POME (about 47 mg L −1 COD) with the initial pH of 7.0 and supplementation of 0.4% nitrogen could be used as a culture medium for the growth and production of antifungal compounds of S. philanthi RL-1-138. In addition, the antifungal compound RM-1-138 could suppress the three strains of oil palm fungal pathogen tested on oil palm leaf segment.