芽孢乳杆菌发酵葡萄糖制备D(-)-乳酸的研究

在国内首次报道了发酵法制备D(-)-乳酸,采用芽孢乳杆菌(Sporolactobacillus sp．)从葡萄糖发酵制备D-乳酸。该发酵为微需氧,发酵培养基组成(g/L):葡萄糖60,酵母膏6,玉米浆5,NH4NO3l,麸皮2,NaH2PO4 4,CaCO340。发酵液的初始pH为7．0.在最佳条件下,37℃发酵72h可产40．7g/L的D-乳酸,葡萄糖转化率67．83％。通过离子配位色谱分析,产物的D-乳酸光学纯度为96．04％e．e．。     

Production of D(-)-lactic acid from cellulose by simultaneous saccharification and fermentation using Lactobacillus coryniformis subsp. torquens

D(–)-Lactic acid was produced from cellulose by simultaneous saccharification and fermentation (SSF) in media containing cellulolytic enzymes and Lactobacillus coryniformis subsp. torquens ATCC 25600 at 39 °C and pH 5.4, yielding 0.89 g D(–)-lactic acid g^–1 cellulose at a mean volumetric productivity of 0.5 g l^–1 h^–1. No L(+)-lactic acid was found in the medium.     

Colorimetric method for the determination of ketoses using phenol-acetone-boric acid reagent (PABR)

A purplish pink color developed when ketose solution (100 μl) was mixed with phenolacetone-boric acid reagent (0.5 ml 5% phenol, 2% acetone, 4% boric acid) and then treated with 96% sulfuric acid (1.4 ml). The absorbance of the reaction mixture was measured at 568 nm after 60 min at 37°C. This method allowed the simple determination of 3–50 nmol of d-fructose with coefficient of variation 7.8% for 3 nmol and 2.8% for 50 nmol. Carbohydrates other then ketoses did not interfere with this reaction. The influence of various chemicals on the colorimetric reaction and applicability of the method for determination of ketoses in natural products are presented.     

A simple method for the quantitative determination of muramic acid

A simple method for microdetermination of muramic acid is elaborated. The method is based on the degradation of muramic acid to lactic acid, followed by degradation of the latter to acetaldehyde which can be determined colorimetrically with p-hydroxydiphenyl (PHD). A linear relationship exists between the concentration of muramic acid (up to 20 μg), and absorbance at 560 nm. Substances usually present in the hydrolysates of bacterial cell wall peptidoglycan do not interfere in the determination.     

A method for the isolation and determination of ferric ethylenediamine di(o-hydroxyphenylacetic acid) in soil studies

Summary Contraversal results about the behaviour of Fe-EDDHA in soils is thought to be due to the indirect methods used for determining the iron chelate compound in soils. The purpose of this investigation is to develop a method for isolation of Fe-EDDHA from soil extracts inorder to be determined separatly. A 4% solution of tetra-n-heptylammonium iodide in ethyl alcohol was found effective in forming a water-insoluble but n-amyl alcohol-soluble compound of Fe-EDDHA. It was found that the absorption spectra of the iron chelate extracted with n-amyl alcohol has an absorption maximum of 480 mμ corresponding to that of iron chelate of the aqueous solution. The extracted iron chelate adhers to Beer's low in the range of 0 to 120 ppm of Fe-EDDHA. The method of Fe-EDDHA extraction was found to be selective for the isolation of the iron chelate from other soluble compounds. The procedure was also found to be highly efficient in quantitative isolation of Fe-EDDHA, with percent recovery ranging from 97–100. The incubation study of Fe-EDDHA in different soils indicated that the loss of Fe-EDDHA is associated with the organic matter content in the soil. The colorimetric determination of the total metal chelates did not indicate any replacement of other metals for the chelated iron in the soil.     

A novel method for nucleic acid sequence determination

We describe a novel sequencing methodology which should be readily and completely automated. The method relies on fragmentation of a nucleotide or deoxynucleotide sequence into short fragments, and subsequent quantitation of the fragments by hybridization to oligo-deoxynucleotides on a solid support. The original sequence may be reconstructed from the resulting table of fragment frequencies. We present a specific protocol which would allow practical implementation of this approach.     

A rapid method for the determination of bacterial fatty acid composition

Heat treatment of spores of non-proteolytic strains of Clostridium botulinum at 75–90°C, and enumeration of survivors on a nutrient medium containing lysozyme gave biphasic survival curves. A majority of spores were inactivated rapidly by heating, and the apparent heat-resistance of these spores was similar to that observed by enumeration on medium without lysozyme. A minority of spores showed much greater heat-resistance, due to the fact that the spore coat was permeable to lysozyme, which diffused into the spore from the medium and replaced the heat-inactivated germination system. The proportion of heated spores permeable to lysozyme was between 0.2 and 1.4% for spores of strains 17B (type B) and Beluga (type E), but was about 20% for spores of strain Foster B96 (type E). After treatment of heated spores with alkaline thioglycolate, all were permeable to lysozyme. D-values for heated spores that were permeable to lysozyme (naturally and after treatment with thioglycolate) were: for strain 17B, D₈₅°C, 100 min; D₉₀°C, 18.7 min; D₉₅°C, 4.4 min; for strain Beluga, D₈₅°C, 46 min; D₉₀°C, 11.8 min; D₉₅°C, 2.8 min. The z-values for these spores of strains 17B and Beluga were 7.6°C and 8.3°C.