1. Biotechnology

Category Archives: Biotechnology

Xylan oligosaccharides and cellobiohydrolase I (TrCel7A) interaction and effect on activity

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Background:
The well studied cellulase mixture secreted by Trichoderma reesei (anamorph to Hypocrea jecorina) contains two cellobiohydolases (CBH, TrCel7A and TrCel6a) that are core enzymes for the solubilisation of cellulose. This has attracted significant research interest due the role of the CBHs in the conversion of biomass to fermentable sugars. However, the CHBs are notoriously slow and susceptible to inhibition, and this challenges the commercial utilization of biomass. One cause of reduced activity that has been suggested repeatedly is the xylans and xylan fragments that are also present in the biomass. Yet, the extent and mechanisms of this inhibition remains poorly elucidated. Therefore, we have studied xylan oligoscaccharides (XOS) of variable lengths with respect to their binding and inhibition of both TrCel7A and an enzyme variant without the cellulose binding domain (CBM).
Results:
The binding of xylan oligosaccharides (XOS) to TrCel7A is studied by isothermal titration calorimetry. It is shown that XOS bind to TrCel7A and that the affinity increases commensurate with the XOS length. The cellulose binding domain, on the other hand, does not affect the affinity significantly; this suggests that XOS may bind to the active site. Activity assays of TrCel7a clearly demonstrate the negative effect of the presence of XOS on the turnover number.
Conclusions:
On the basis of these binding data and a comparison of XOS inhibition of the activity of the two enzyme variants towards, respectively, soluble and insoluble substrates, we propose a competitive mechanism for XOS inhibition of TrCel7A with phosphoric swollen cellulose as a substrate.Source:
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Mychonastes afer HSO-3-1 as a potential new source of biodiesel

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Background:
Biodiesel is considered to be a promising future substitute for fossil fuels, and microalgae are one source of biodiesel. The ratios of lipid, carbohydrates and proteins are different in different microalgal species, and finding a good strain for oil production remains a difficult prospect. Strains producing valuable co-products would improve the viability of biofuel production.
Results:
In this study, we performed sequence analysis of the 18S rRNA gene and internal transcribed spacer (ITS) of an algal strain designated HSO-3-1, and found that it was closely related to the Mychonastes afer strain CCAP 260/6. Morphology and cellular structure observation also supported the identification of strain HSO-3-1 as M. afer. We also investigated the effects of nitrogen on the growth and lipid accumulation of the naturally occurring M. afer HSO-3-1, and its potential for biodiesel production. In total, 17 fatty acid methyl esters (FAMEs) were identified in M. afer HSO-3-1, using gas chromatography/mass spectrometry. The total lipid content of M. afer HSO-3-1 was 53.9% of the dry cell weight, and we also detected nervonic acid (C24:1), which has biomedical applications, making up 3.8% of total fatty acids). The highest biomass and lipid yields achieved were 3.29 g/l and 1.62 g/l, respectively, under optimized conditions.
Conclusion:
The presence of octadecenoic and hexadecanoic acids as major components, with the presence of a high-value component, nervonic acid, renders M. afer HSO-3-1 biomass an economic feedstock for biodiesel production.Source:
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Silage produces biofuel for local consumption

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Background:
In the normal process of bio-ethanol production, biomass is transported to integrated large factories for degradation to sugar, fermentation, and recovery of ethanol by distillation. Biomass nutrient loss occurs during preservation and degradation. Our aim was to develop a decentralized ethanol production system appropriate for farm or co-operative level production that uses a solid-state fermentation method for producing bio-ethanol from whole crops, provides cattle feed, and produces no wastes. The idea is to incorporate traditional silage methods with simultaneous saccharification and fermentation. Harvested, fresh biomass is ensiled with biomass-degrading enzymes and yeast. Multiple parallel reactions for biomass degradation and ethanol and lactic acid production are induced in solid culture in hermetically sealed containers at a ranch. After fermentation, ethanol is collected on site from the vapor from heated fermented products.
Results:
The parallel reactions of simultaneous saccharification and fermentation were induced efficiently in the model fermentation system. In a laboratory-scale feasibility study of the process, 250 g of freshly harvested forage rice with 62% moisture was treated with 0.86 filter paper units/g dry matter (DM) of cellulase and 0.32 U/g DM of glucoamylase. After 20 days of incubation at 28 degreesC, 6.4 wt.% of ethanol in fresh matter (equivalent to 169 g/kg DM) was produced. When the 46 wt.% moisture was gathered as vapor from the fermented product, 74% of the produced ethanol was collected. Organic cellular contents (such as the amylase and pronase degradable fractions) were decreased by 63% and organic cell wall (fiber) content by 7% compared to silage prepared from the same material.
Conclusions:
We confirmed that efficient ethanol production is induced in nonsterilized whole rice plants in a laboratory-scale solid-state fermentation system. For practical use of the method, further study is needed to scale-up the fermentation volume, develop an efficient ethanol recovery method, and evaluate the fermentation residue as an actual cattle feed.Source:
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Ensiling of crops for biogas production: effects on methane yield and total solids determination

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Background:
Ensiling is a common method of preserving energy crops for anaerobic digestion, and many scientific studies report that ensiling increases the methane yield. In this study, the ensiling process and the methane yield before and after ensiling were studied for four crop materials.
Results:
The changes in wet weight and total solids (TS) during ensiling were small and the loss of energy negligible. The methane yields related to wet weight and to volatile solids (VS) were not significantly different before and after ensiling when the VS were corrected for loss of volatile compounds during TS and VS determination. However, when the TS were measured according to standard methods and not corrected for losses of volatile compounds, the TS loss during ensiling was overestimated for maize and sugar beet. The same methodological error leads to overestimation of methane yields; when TS and VS were not corrected the methane yield appeared to be 51% higher for ensiled than fresh sugar beet.
Conclusions:
Ensiling did not increase the methane yield of the studied crops. Published methane yields, as well as other information on silage related to uncorrected amounts of TS and VS, should be regarded with caution.Source:
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Biotechnology at the Cutting Edge – Keasling – Video

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Jay Keasling, Berkeley Lab ALD for Biosciences and CEO of the Joint BioEnergy Institute, appears in a video on biotechnology at the Smithsonian's National Museum of American History. The video is part of en exhibit titled "Science in American Life," which examines the relationship between science, technology, progress and culture through artifacts, historical photographs and multimedia technology.

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Biotechnology at the Cutting Edge - Keasling - Video

Unlimited Income Potential in Bio-Technology, Part 1 – Video

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Unlimited Income Potential in Bio-Technology, Part 1 - Video

BioBytes: Forensics and Biotechnology – Video

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How many times have you watched your favorite crime drama and wondered just how that forensic DNA technology actually works? Well, as it turns out, it has a lot to do with biotechnology. By utilizing DNA, scientists are able to create a genetic finger print that is unique to each individual to help find and prosecute crime suspects and identify remains

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BioBytes: Forensics and Biotechnology - Video

Faces of Biotechnology: What is Biotechnology – Video

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People working in biotechnology fields (try to) explain what biotechnology is. This project is 100% funded by a Workforce Innovation in Regional Economic Development (WIRED) grant from the US Department of Labor, Employment and Training Administration, working in partnership with the Governor's Office of Economic Development and the Utah Department of Workforce Services.

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Faces of Biotechnology: What is Biotechnology - Video


  1. Biotechnology