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Displaying publications 61 - 69 of 69 in total

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Fulltext Tree shrew lavatories: a novel nitrogen sequestration strategy in a tropical pitcher plant

Clarke CM, Bauer U, Lee CC, Tuen AA, Rembold K, Moran JA

Biol Lett, 2009 Oct 23;5(5):632-5.
PMID: 19515656 DOI: 10.1098/rsbl.2009.0311

Nepenthes pitcher plants are typically carnivorous, producing pitchers with varying combinations of epicuticular wax crystals, viscoelastic fluids and slippery peristomes to trap arthropod prey, especially ants. However, ant densities are low in tropical montane habitats, thereby limiting the potential benefits of the carnivorous syndrome. Nepenthes lowii, a montane species from Borneo, produces two types of pitchers that differ greatly in form and function. Pitchers produced by immature plants conform to the 'typical' Nepenthes pattern, catching arthropod prey. However, pitchers produced by mature N. lowii plants lack the features associated with carnivory and are instead visited by tree shrews, which defaecate into them after feeding on exudates that accumulate on the pitcher lid. We tested the hypothesis that tree shrew faeces represent a significant nitrogen (N) source for N. lowii, finding that it accounts for between 57 and 100 per cent of foliar N in mature N. lowii plants. Thus, N. lowii employs a diversified N sequestration strategy, gaining access to a N source that is not available to sympatric congeners. The interaction between N. lowii and tree shrews appears to be a mutualism based on the exchange of food sources that are scarce in their montane habitat.

Matched MeSH terms: Nitrogen/metabolism*
Fulltext Enhancing microalga Chlorella sorokiniana CY-1 biomass and lipid production in palm oil mill effluent (POME) using novel-designed photobioreactor

Cheah WY, Show PL, Yap YJ, Mohd Zaid HF, Lam MK, Lim JW, et al.

Bioengineered, 2020 12;11(1):61-69.
PMID: 31884878 DOI: 10.1080/21655979.2019.1704536

Chlorella sorokiniana CY-1 was cultivated using palm oil mill effluent (POME) in a novel-designed photobioreactor (NPBR) and glass-made vessel photobioreactor (PBR). The comparison was made on biomass and lipid productions, as well as its pollutants removal efficiencies. NPBR is transparent and is developed in thin flat panels with a high surface area per volume ratio. It is equipped with microbubbling and baffles retention, ensuring effective light and CO2 utilization. The triangular shape of this reactor at the bottom serves to ease microalgae cell harvesting by sedimentation. Both biomass and lipid yields attained in NPBR were 2.3-2.9 folds higher than cultivated in PBR. The pollutants removal efficiencies achieved were 93.7% of chemical oxygen demand, 98.6% of total nitrogen and 96.0% of total phosphorus. Mathematical model revealed that effective light received and initial mass contributes toward successful microalgae cultivation. Overall, the results revealed the potential of NPBR integration in Chlorella sorokiniana CY-1 cultivation, with an aim to achieve greater feasibility in microalgal-based biofuel real application and for environmental sustainability.

Matched MeSH terms: Nitrogen/metabolism
Fulltext Repeated batch fermentation biotechnology for the biosynthesis of lipid and gamma-linolenic acid by Cunninghamella bainieri 2A1

Ganjali Dashti M, Abdeshahian P, Wan Yusoff WM, Kalil MS, Abdul Hamid A

Biomed Res Int, 2014;2014:831783.
PMID: 25147817 DOI: 10.1155/2014/831783

The biosynthesis of biomedical products including lipid and gamma-linolenic acid (GLA) by Cunninghamella bainieri 2A1 was studied in repeated batch fermentation. Three key process variables, namely, glucose concentration, ammonium tartrate concentration, and harvesting time, were optimized using response surface methodology. Repeated batch fermentation was carried out by the cultivation of Cunninghamella bainieri 2A1 in nitrogen-limited medium with various nitrogen concentration (1-4 g/L) and glucose concentration (20-40 g/L) at three time intervals (12 h, 24 h, and 48 h). Experimental results showed that the highest lipid concentration of 6.2 g/L and the highest GLA concentration of 0.4 g/L were obtained in optimum conditions, where 20.2 g/L glucose, 2.12 g/L ammonium tartrate, and 48 h harvesting time were utilized. Statistical results showed that the interaction between glucose and ammonium tartrate concentration had highly significant effects on lipid and GLA biosynthesis (P < 0.01). Moreover, harvesting time had a significant interaction effect with glucose and ammonium tartrate concentration on lipid production (P < 0.05).

Matched MeSH terms: Nitrogen/metabolism
Fulltext Microbial Decolorization of Triazo Dye, Direct Blue 71: An Optimization Approach Using Response Surface Methodology (RSM) and Artificial Neural Network (ANN)

Zin KM, Effendi Halmi MI, Abd Gani SS, Zaidan UH, Samsuri AW, Abd Shukor MY

Biomed Res Int, 2020;2020:2734135.
PMID: 32149095 DOI: 10.1155/2020/2734135

The release of wastewater from textile dyeing industrial sectors is a huge concern with regard to pollution as the treatment of these waters is truly a challenging process. Hence, this study investigates the triazo bond Direct Blue 71 (DB71) dye decolorization and degradation dye by a mixed bacterial culture in the deficiency source of carbon and nitrogen. The metagenomics analysis found that the microbial community consists of a major bacterial group of Acinetobacter (30%), Comamonas (11%), Aeromonadaceae (10%), Pseudomonas (10%), Flavobacterium (8%), Porphyromonadaceae (6%), and Enterobacteriaceae (4%). The richest phylum includes Proteobacteria (78.61%), followed by Bacteroidetes (14.48%) and Firmicutes (3.08%). The decolorization process optimization was effectively done by using response surface methodology (RSM) and artificial neural network (ANN). The experimental variables of dye concentration, yeast extract, and pH show a significant effect on DB71 dye decolorization percentage. Over a comparative scale, the ANN model has higher prediction and accuracy in the fitness compared to the RSM model proven by approximated R2 and AAD values. The results acquired signify an efficient decolorization of DB71 dye by a mixed bacterial culture.

Matched MeSH terms: Nitrogen/metabolism
Fulltext Molybdate reduction to molybdenum blue by an Antarctic bacterium

Ahmad SA, Shukor MY, Shamaan NA, Mac Cormack WP, Syed MA

Biomed Res Int, 2013;2013:871941.
PMID: 24381945 DOI: 10.1155/2013/871941

A molybdenum-reducing bacterium from Antarctica has been isolated. The bacterium converts sodium molybdate or Mo⁶⁺ to molybdenum blue (Mo-blue). Electron donors such as glucose, sucrose, fructose, and lactose supported molybdate reduction. Ammonium sulphate was the best nitrogen source for molybdate reduction. Optimal conditions for molybdate reduction were between 30 and 50 mM molybdate, between 15 and 20°C, and initial pH between 6.5 and 7.5. The Mo-blue produced had a unique absorption spectrum with a peak maximum at 865 nm and a shoulder at 710 nm. Respiratory inhibitors such as antimycin A, sodium azide, potassium cyanide, and rotenone failed to inhibit the reducing activity. The Mo-reducing enzyme was partially purified using ion exchange and gel filtration chromatography. The partially purified enzyme showed optimal pH and temperature for activity at 6.0 and 20°C, respectively. Metal ions such as cadmium, chromium, copper, silver, lead, and mercury caused more than 95% inhibition of the molybdenum-reducing activity at 0.1 mM. The isolate was tentatively identified as Pseudomonas sp. strain DRY1 based on partial 16s rDNA molecular phylogenetic assessment and the Biolog microbial identification system. The characteristics of this strain would make it very useful in bioremediation works in the polar and temperate countries.

Matched MeSH terms: Nitrogen/metabolism*
Fulltext Optimal reduction of chemical oxygen demand and NH3-N from landfill leachate using a strongly resistant novel Bacillus salmalaya strain

Dadrasnia A, Azirun MS, Ismail SB

BMC Biotechnol, 2017 Nov 28;17(1):85.
PMID: 29179747 DOI: 10.1186/s12896-017-0395-9

BACKGROUND: When the unavoidable waste generation is considered as damaging to our environment, it becomes crucial to develop a sustainable technology to remediate the pollutant source towards an environmental protection and safety. The development of a bioengineering technology for highly efficient pollutant removal is this regard. Given the high ammonia nitrogen content and chemical oxygen demand of landfill leachate, Bacillus salmalaya strain 139SI, a novel resident strain microbe that can survive in high ammonia nitrogen concentrations, was investigated for the bioremoval of ammonia nitrogen from landfill leachate. The treatability of landfill leachate was evaluated under different treatment parameters, such as temperature, inoculum dosage, and pH.
RESULTS: Results demonstrated that bioaugmentation with the novel strain can potentially improve the biodegradability of landfill leachate. B. salmalaya strain 139SI showed high potential to enhance biological treatment given its maximum NH3-N and COD removal efficiencies. The response surface plot pattern indicated that within 11 days and under optimum conditions (10% v/v inoculant, pH 6, and 35 °C), B. salmalaya strain139SI removed 78% of ammonia nitrogen. At the end of the study, biological and chemical oxygen demands remarkably decreased by 88% and 91.4%, respectively. Scanning electron microscopy images revealed that ammonia ions covered the cell surface of B. salmalaya strain139SI.
CONCLUSIONS: Therefore, novel resistant Bacillus salmalaya strain139SI significantly reduces the chemical oxygen demand and NH3-N content of landfill leachate. Leachate treatment by B. salmalaya strain 139SI within 11 days.

Matched MeSH terms: Nitrogen/metabolism
Effects of feedstock carbon to nitrogen ratio and organic loading on foaming potential in mesophilic food waste anaerobic digestion

Tanimu MI, Mohd Ghazi TI, Harun MR, Idris A

Appl Microbiol Biotechnol, 2015 May;99(10):4509-20.
PMID: 25761621 DOI: 10.1007/s00253-015-6486-4

Foaming problem which occurred occasionally during food waste (FW) anaerobic digestion (AD) was investigated with the Malaysian FW by stepwise increase in organic loading (OL) from 0.5 to 7.5 g VS/L. The FW feedstock with carbon to nitrogen (C/N) ratio of 17 was upgraded to C/N ratio of 26 and 30 by mixing with other wastes. The digestion which was carried out at 37 °C in 1-L batch reactors showed that foam formation initiated at OL of 1.5 g VS/L and was further enhanced as OL of feedstock was increased. The digestion foaming reached its maximum at OL of 5.5 g VS/L and did not increase further even when OL was increased to 7.5 g VS/Ld. Increase in the C/N ratio of feedstock significantly enhanced the microbial degradation activity, leading to better removal of foam causing intermediates and reduced foaming in the reactor by up to 60%.

Matched MeSH terms: Nitrogen/metabolism*
Evaluation of aeration strategy in moving bed sequencing batch reactor performing simultaneous 4-chlorophenol and nitrogen removal

Lim JW, Lim PE, Seng CE, Adnan R

Appl Biochem Biotechnol, 2013 Jun;170(4):831-40.
PMID: 23613119 DOI: 10.1007/s12010-013-0245-8

The aeration strategy ranging from intermittent to continuous aeration in the REACT period of moving bed sequencing batch reactor (MBSBR) was evaluated for simultaneous removal of 4-chlorophenol (4-CP) and nitrogen. The results show that the removal rates of 4-CP and ammonium nitrogen (NH(4)(+)-N) increased with the increase of continuous aeration period. In the presence of 4-CP, NH(4)(+)-N removal was mainly by the assimilation process. The removal of NH(4)(+)-N to oxidized nitrogen via oxidation was only observed after 4-CP was completely degraded with sufficient aeration period provided indicating the inhibitory effect of 4-CP on nitrification. As the intermittent aeration strategy would lead to slower 4-CP degradation resulting in the delay of nitrification process, continuous aeration would be the preferred strategy in the simultaneous removal of 4-CP and nitrogen in the MBSBR system.

Matched MeSH terms: Nitrogen/metabolism*
Oil palm empty fruit bunch as alternative substrate for acetone-butanol-ethanol production by Clostridium butyricum EB6

Ibrahim MF, Abd-Aziz S, Razak MN, Phang LY, Hassan MA

Appl Biochem Biotechnol, 2012 Apr;166(7):1615-25.
PMID: 22391689 DOI: 10.1007/s12010-012-9538-6

Acetone-butanol-ethanol (ABE) production from renewable resources has been widely reported. In this study, Clostridium butyricum EB6 was employed for ABE fermentation using fermentable sugar derived from treated oil palm empty fruit bunch (OPEFB). A higher amount of ABE (2.61 g/l) was produced in a fermentation using treated OPEFB as the substrate when compared to a glucose based medium that produced 0.24 g/l at pH 5.5. ABE production was increased to 3.47 g/l with a yield of 0.24 g/g at pH 6.0. The fermentation using limited nitrogen concentration of 3 g/l improved the ABE yield by 64%. The study showed that OPEFB has the potential to be applied for renewable ABE production by C. butyricum EB6.

Matched MeSH terms: Nitrogen/metabolism