Optimization and microbial community analysis for production of biogas from solid waste residues of palm oil mill industry by solid-state anaerobic digestion.

This study investigated the improvement of biogas production from solid-state anaerobic digestion (SS-AD) of oil palm biomass by optimizing of total solids (TS) contents, feedstock to inoculum (F:I) ratios and carbon to nitrogen (C:N) ratios. Highest methane yield from EFB, OPF and OPT of 358, 280 and 324m(3)CH4ton(-1)VS, respectively, was achieved at TS content of 16%, C:N ratio of 30:1 and F:I ratio of 2:1. The main contribution to methane from biomass was the degradation of cellulose and hemicellulose. The highest methane production of 72m(3)CH4ton(-1) biomass was achieved from EFB. Bacteria community structure in SS-AD process of oil palm biomass was dominated by Ruminococcus sp. and Clostridium sp., while archaea community was dominated by Methanoculleus sp. Oil palm biomass has great potential for methane production via SS-AD.

Characterization of polyhydroxyalkanoates (PHAs) biosynthesis by isolated Novosphingobium sp. THA_AIK7 using crude glycerol.

Biodiesel-contaminated wastewater was used to screen for PHAs-producing bacteria by using crude glycerol as the sole carbon source. A gram-negative THA_AIK7 isolate was chosen as a potential PHAs producer. The 16S rRNA phylogeny indicated that THA_AIK7 isolate is a member of Novosphingobium genus which is supported by a bootstrap percentage of 100% with Novosphingobium capsulatum. The 1,487 bp of 16S rRNA gene sequence of THA_AIK7 isolate has been deposited in the GenBank database under the accession number HM031593. Polymer content of 45% cell dry weight was achieved in 72 h with maximum product yield coefficient of 0.29 g PHAs g⁻¹ glycerol. Transmission electron micrograph results exhibited the PHAs granules accumulated inside the bacterial cell. PHAs polymer production in mineral salt media supplemented with 2% (w/v) of crude glycerol at initial pH 7 was extracted by the sodium hypochlorite method. Polymer film spectrographs from Nuclear magnetic resonance displayed a pattern of signal virtually identical to spectra of commercial PHB. Thermal analysis by Differential scanning calorimeter showed a melting temperature at 179°C. Molecular weight analysis by Gel permeation chromatography showed two main peaks of 133,000 and 700 g mol⁻¹ with weight-average molecular weight value of 23,800 and number-average molecular weight value of 755. Endotoxinfree of PHAs polymer was preliminarily assessed by a negative result of the gel-clot formation, Pyrotell® Single test vial, at sensitivity of 0.25 EU ml⁻¹. To our knowledge, this is the first reported test of endotoxin-free PHAs naturally produced from gram-negative bacteria which could be used for biomedical application.

L-Ascorbate biosynthesis in peach: cloning of six L-galactose pathway-related genes and their expression during peach fruit development.

The L-ascorbate (AsA) content and the expression of six L-galactose pathway-related genes were analyzed in peach flesh during fruit development. Fluctuation of AsA during peach fruit development was divided into four phases based on the overall total AsA (T-AsA) content per fruit: AsA I, 0-36 days after full bloom (DAFB); AsA II, 37-65 DAFB; AsA III, 66-92 DAFB and AsA IV, 93-112 DAFB. Phase AsA III was a lag phase for AsA accumulation, but did not coincide with the lag phase for fruit development. The T-AsA concentration was highest at the early stage until 21 DAFB [2-3 micromol per gram of fresh weight (g(-1) FW)], and decreased to 1/4 and 1/15 of this value at 50 and 92 DAFB, respectively. T-AsA then remained at 0.15-0.20 micromol g(-1) FW until harvest at 112 DAFB. More than 90% of the T-AsA was in the reduced form until 21 DAFB. The proportion of reduced form of AsA then decreased concomitantly with the decrease in AsA concentration. To determine the main pathway of AsA biosynthesis and the AsA biosynthetic capacity of peach flesh, several precursors were incubated with immature whole fruit (59 DAFB). The AsA concentration increased markedly with L-galactono-1,4-lactone or L-galactose (Gal), but d-galacturonate and L-gulono-1,4-lactone failed to increase AsA, indicating dominance of the Gal pathway and potent AsA biosynthetic capabilities in immature peach flesh. The expression of genes involved in the last six steps of the Gal pathway was measured during fruit development. The genes studied included GDP-d-mannose pyrophosphorylase (GMPH), GDP- d-mannose-3',5'-epimerase (GME), GDP- L-galactose guanylyltransferase (GGGT), L-galactose-1-phosphate phosphatase (GPP), L-galactose-1-dehydrogenase (GDH) and L-galactono-1,4-lactone dehydrogenase (GLDH). GMPH, GME and GGGT had similar expression patterns that peaked at 43 DAFB. GPP, GDH and GLDH also had similar expression patterns that peaked twice at 21 and 91 DAFB, although the expression of GDH was quite low. High level of T-AsA concentration was roughly correlated with the level of gene expression in the early period of fruit development (AsA I), whereas no such relationships were apparent in the other periods (e.g. AsA III and IV). On the basis of these findings, we discuss the regulation of AsA biosynthesis in peach fruit.

Water environment conservation in a closed water body by high concentrated oxygen water.

In this study, the method of using high concentrated oxygen water to purify the bottom sediment was confirmed to be effective. The high concentrated oxygen dissolver was developed and the lab scale experiment was performed. High rate, high efficiency oxygen dissolver was developed, the optimum running condition of the apparatus and the method of producing high concentrated oxygen water was discussed and determined in this study. In addition, the effective prevention of phosphorus release from anaerobic bottom sediment was also studied. As a result, it is found that high concentrated oxygen water was effective for prevention of phosphorus release from anaerobic bottom sediment. On the basis of the fundamental knowledge from the laboratory-scale study, pilot scale apparatus was set up and the pilot study was carried out. It is showed that the introduction of high concentrated oxygen water did not destroy the thermocline of dam reservoir.

Factors affecting hydrogen production from cassava wastewater by a co-culture of anaerobic sludge and Rhodospirillum rubrum.

Series of batch experiments were used to investigate the effects of environmental factors, i.e., total nitrogen and total phosphorus concentrations, initial pH, illumination pattern and stirring conditions on hydrogen production from cassava wastewater by a co-culture of anaerobic sludge and Rhodospirillum rubrum. The maximum of the hydrogen yield of 150.46 and 340.19 mL g-COD(-1) was obtained at the total nitrogen and total phosphorus concentrations of 0.2 and 0.04 M, respectively. An effect of initial pH was investigated at COD:N:P ratio of 100:10:1. Results indicated that an optimum initial pH for hydrogen production was pH 7 with a high hydrogen yield of 158.78 mL g-COD(-1) was obtained. No significantly different (p < 0.05) in the effect of illumination pattern (24 h of light and 12 h dark/light cycle) on hydrogen production were observed under continuous-illumination and periodic-illumination with hydrogen yield of 131.84 and 126.92 mL g-COD(-1), respectively. Therefore, a periodic-illumination was applicable in hydrogen fermentation due to its cost-effective. Hydrogen fermentation with a stirring at 100 rpm provided more effective hydrogen production (164.83 mL g-COD(-1)) than static-fermentation (93.93 mL g-COD(-1)). The major soluble products from hydrogen fermentation were acetic and butyric acids, in the ranges of 28.33-48.30 and 35.23-66.07%, respectively, confirming an ability of a co-culture to produce hydrogen from cassava wastewater.