scholarly journals Preparation and Characterization of Polylactic Acid Microspheres Containing Water-Soluble Anesthetics with Small Molecular Weight.

1997 ◽  
Vol 45 (3) ◽  
pp. 513-517 ◽  
Author(s):  
Takahiro UCHIDA ◽  
Kazushi YOSHIDA ◽  
Yoichi NAKADA ◽  
Noriko NAGAREYA ◽  
Yuriko KONISHI ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Polylactic Acid ◽  
Water Soluble ◽  
Small Molecular Weight

Characterization of water soluble pentosans of enzyme supplemented dough and breads/ Caracterización de las pentosanas solubles en agua extraídas de masa y pan conteniendo enzimas comerciales

2000 ◽  
Vol 6 (3) ◽  
pp. 197-205 ◽  
Author(s):  
T. Jimenez ◽  
M.A. Martinez-Anaya
Keyword(s):  
Molecular Weight ◽  
Ferulic Acid ◽  
Synergistic Effects ◽  
Extraction Yield ◽  
Water Soluble ◽  
Sugar Composition ◽  
Enzyme Preparations ◽  
Processing Enzyme ◽  
Enzyme Source

Water soluble pentosans (WSP) from doughs and breads made with different enzyme preparations are characterized according to extraction yield, sugar composition, xylose/arabinose ratio and molecular weight (MW) distribution. Extraction yield was greater for dough than for bread samples, ranging from 0.94 to 1.64%, but bread extracts had a higher purity. Percent of pentoses in purified WSP was greater in pentosanase supplemented samples (28-55%) than in control and amylase containing samples (23-32%). Major sugars were xylose and arabinose, but glucose and mannose also appeared in the extracts. The xylose/arabinose (Xyl/Ara) ratio was 1.3-1.6 and underwent small changes during processing. Enzyme addition caused an increase in Xyl/Ara ratio, attributable to a debranching of arabinoxylans (AX) with higher degree of Ara substitution by arabinofuranosidase. Addition of pentosanases had a significant effect in increasing WSP with MW over 39 000, whereas those of low MW changed only slightly. MW distribution depended on enzyme source, and whereas some enzymes showed activity during fermentation others increased their activity during baking. No synergistic effects were observed in studied variables due to the combination of amylases with pentosanases. Protein in WSP extracts eluted together with ferulic acid suggesting they were linked, but not associated with a determined carbohydrate fraction.

Isolation and characterization of a bacteriocin produced by Bacillus stearothermophilus strain NU-10

1976 ◽  
Vol 22 (12) ◽  
pp. 1743-1750 ◽  
Author(s):  
Ronald Yule ◽  
B. D. Barridge
Keyword(s):  
Molecular Weight ◽  
Stationary Phase ◽  
Bacillus Stearothermophilus ◽  
Proteolytic Enzymes ◽  
Small Molecular Weight ◽  
Optimal Production ◽  
Chemical Treatments ◽  
Neutral Ph ◽  
Isolation And Characterization

Broth-grown cultures of Bacillus stearothermophilus strain NU-10 produce a bacteriocin which exerts lethal activity on other strains of the bacterium. Optimal production occurs during late maximum stationary phase of growth, at neutral pH, and 55–65 °C. The bacteriocin can be substantially purified by a combination of precipitations, centrifugations, and gel filtrations. The thermocin is composed of protein and carbohydrate. It is partially destroyed by proteolytic enzymes but is resistant to DNase, RNase, and various chemical treatments. The bacteriocin has a small molecular weight and exhibits considerable thermostability.

scholarly journals Construction of soil defined media using quantitative exometabolomic analysis of soil metabolites

2017 ◽  
Author(s):  
Stefan Jenkins ◽  
Tami L Swenson ◽  
Rebecca Lau ◽  
Andrea Rocha ◽  
Alex Aaring ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Molecular Weight ◽  
Organic Carbon ◽  
Quantitative Information ◽  
Water Soluble ◽  
Gas Chromatography Mass Spectrometry ◽  
Isolation And Characterization ◽  
Defined Media ◽  
Chromatography Mass Spectrometry

Exometabolomics enables analysis of metabolite utilization of low molecular weight organic substances by soil isolates. Environmentally-based defined media are needed to examine ecologically relevant patterns of substrate utilization. Here, we describe an approach for the construction of defined media using untargeted characterization of water soluble soil metabolites. To broadly characterize soil metabolites, both liquid chromatography mass spectrometry (LC/MS) and gas chromatography mass spectrometry (GC/MS) were used. With this approach, 96 metabolites were identified, including amino acids, amino acid derivatives, sugars, sugar alcohols, mono- and di-carboxylic acids, osmolytes, nucleobases, and nucleosides. From this pool of metabolites, 25 were quantified. Water soluble organic carbon was fractionated by molecular weight and measured to determine the fraction of carbon accounted for by the quantified metabolites. This revealed that, much like soil microbial community structures, these soil metabolites have an uneven quantitative distribution, with a single metabolite, trehalose accounting for 9.9 percent of the (< 1 kDa) water extractable organic carbon. This quantitative information was used to formulate two soil defined media (SDM), one containing 23 metabolites (SDM1) and one containing 46 (SDM2). To evaluate SDM for supporting the growth of bacteria found at this field site, we examined the growth of 30 phylogenetically diverse soil isolates obtained using standard R2A medium. The simpler SDM1 supported the growth of up to 13 isolates while the more complex SDM2 supported up to 25 isolates. One isolate, Pseudomonas corrugata strain FW300-N2E2 was selected for a time-series exometabolomics analysis to investigate SDM1 substrate preferences. Interestingly, it was found that this organism preferred lower-abundance substrates such as guanine, glycine, proline and arginine and glucose and did not utilize the more abundant substrates maltose, mannitol, trehalose and uridine. These results demonstrate the viability and utility of using exometabolomics to construct a tractable environmentally relevant media. We anticipate that this approach can be expanded to other environments to enhance isolation and characterization of diverse microbial communities.

Synthesis and Characterization of Low Molecular Weight Polylactic Acid

2002 ◽  
Vol 34 (1) ◽  
pp. 49-63 ◽  
Author(s):  
C. S. Proikakis ◽  
P. A. Tarantili ◽  
A. G. Andreopoulos
Keyword(s):  
Molecular Weight ◽  
Polylactic Acid ◽  
Synthesis And Characterization ◽  
Low Molecular Weight

scholarly journals Degradation of Polylactic Acid Using Sub-Critical Water for Compost

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2434
Author(s):  
Toshiharu Goto ◽  
Mikitaka Kishita ◽  
Yin Sun ◽  
Takeshi Sako ◽  
Idzumi Okajima
Keyword(s):  
Molecular Weight ◽  
Polylactic Acid ◽  
Food Packaging ◽  
Crystallization Rate ◽  
General Purpose ◽  
Water Soluble ◽  
Decomposition Rates ◽  
Scanning Calorimetry ◽  
Reaction Conditions ◽  
Decomposition Products

Polylactic acid (PLA) is expected to replace many general-purpose plastics, especially those used for food packaging and agricultural mulch. In composting, the degradation speed of PLA is affected by the molecular weight, crystallinity, and microbial activity. PLA with a molecular weight of less than 10,000 has been reported to have higher decomposition rates than those with higher molecular weight. However, PLA degradation generates water-soluble products, including lactic acid, that decrease the pH of soil or compost. As acidification of soil or compost affects farm products, their pH should be controlled. Therefore, a method for determining suitable reaction conditions to achieve ideal decomposition products is necessary. This study aimed to determine suitable reaction conditions for generating preprocessed PLA with a molecular weight lower than 10,000 without producing water-soluble contents. To this end, we investigated the degradation of PLA using sub-critical water. The molecular weight and ratio of water-soluble contents (WSCs) affecting the pH of preprocessed products were evaluated through kinetic analysis, and crystallinity was analyzed through differential scanning calorimetry. Preprocessed PLA was prepared under the determined ideal conditions, and its characteristics in soil were observed. The results showed that the crystallization rate increased with PLA decomposition but remained lower than 30%. In addition, the pH of compost mixed with 40% of preprocessed PLA could be controlled within pH 5.4–5.5 over 90 days. Overall, soil mixed with the preprocessed PLA prepared under the determined ideal conditions remains suitable for plant growth.

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