Growth requirements and the establishment of a chemically defined minimal medium inZymomonas mobilis

Summary A chemically defined minimal medium which fulfils the growth requirements of differentZymomonas mobilis strains has been established. The kinetics of ethanol production of the strains ATCC 10988, CU1, CP4 and 11163 grown on the minimal medium at different glucose concentrations were measured. All strains produced ethanol at rates similar to those on complete medium. The minimal medium described is suitable to study spontaneous metabolic deficiciencies and regulation of enzyme activities inZ.mobilis.     

Screening of thermostable leucine and alanine dehydrogenases in thermophilicBacillus strains

Summary Screening of leucine and alanine dehydrogenases in thermophilicBacillus strains was carried out to develop their utilization for industrial and analytical catalysts. Out of the 28 thermophilic strains tested, four strains,Bacillus sp. DSM 405, 730 and 1521, andB. sphaericus DSM 462, abundantly produce both the enzymes. Both the enzyme activities in these thermophiles are enhanced by addition of the substrates to a polypeptone medium.     

CMCase production by Spicellum roseum in liquid and solid culture

Summary CMCase was produced by 7 strains of Spicellum roseum in both liquid and wheat bran solid substrate cultures. No growth occurred above 35°C. Maximum enzyme production occurred at 30°C, whereas best enzyme activity occurred at pH 5.0 and 50°C. In liquid cultures of S. roseum, NRRL strains 13103, 13104, and 13106 produced activities of ca. 1.1, 1.5, and 1.5 mg glucose per hr/ml culture supernate at 1 week and 2.9, 1.5, and 2.1, respectively at 3 weeks compared to Trichoderma reesei NRRL 11236 (MCG77), which produced activities of 2.8 and 1.3 at 1 and 3 weeks.The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Simultaneous production of cellulase complex and glucose isomerase by Streptomyces flavogriseus

Summary Fermentations of Streptomyces flavogriseus were carried out at 30° C on media containing either Avicel, hay or acid hay hydrolysate as the principal carbon source. Under these conditions the strains produced simultaneously the enzymes of the cellulase complex as well as glucose isomerase. The enzyme activities were induced by hay, hay extract and D-xylose.     

Selection of yeast able to produce ethanol from glucose at 40° C

Summary A total of 55 yeast strains selected from 7 genera known to ferment carbohydrates to ethanol were screened for their ability to ferment glucose to ethanol in shaken flask culture at 37°, 40° and 45°C. Yields of more than 50% of the theoretical maximum were obtained with 28 strains at 37°C, but only 12 at 40°C. Only 6 could grow at 45°C, but they produced poor yields. In general Kluyveromyces strains were more thermotolerant than Saccharomyces and Candida strains, but Saccharomyces strains produced higher ethanol yields. The 8 strains with the highest yields at 40°C were evaluated in batch fermentations. Three of these, two Saccharomyces and one Candida, were able to meet minimum commercial targets set at 8% (v/v) ethanol from 14% (w/v) glucose at 40°C.     

Brassica grown gall tumourigenesis and in vitro of transformed tissue

A number of Brassica species and cultivars were tested and found to be highly susceptible to crown gall induction by both nopaline and octopine strains of Agrobacterium tumefaciens. Only B. napus did not form tumours when inoculated with octopine strains. Seedlings of very young plants were poor hosts but efficient infection occurred after 8–10 weeks of growth. Teratomas arising on tumours in planta were relatively frequent on induction with nopaline strains. Axenically cultured tumour calli of Brassicas were very active in opine synthase activity and stably maintained this transformed phenotype; however, transformed plants could not be regenerated. These results suggest that disarmed nopaline Ti plasmid vectors are well suited for the genetic engineering of this important crop family.     

Genome sequence analyses of two isolates from the recent <Emphasis Type="Italic">Escherichia coli</Emphasis> outbreak in Germany reveal the emergence of a new pathotype: Entero-Aggregative-Haemorrhagic <Emphasis Type="Italic">Escherichia coli</Emphasis> (EAHEC)

The genome sequences of two Escherichia coli O104:H4 strains derived from two different patients of the 2011 German E. coli outbreak were determined. The two analyzed strains were designated E. coli GOS1 and GOS2 (German outbreak strain). Both isolates comprise one chromosome of approximately 5.31 Mbp and two putative plasmids. Comparisons of the 5,217 (GOS1) and 5,224 (GOS2) predicted protein-encoding genes with various E. coli strains, and a multilocus sequence typing analysis revealed that the isolates were most similar to the entero-aggregative E. coli (EAEC) strain 55989. In addition, one of the putative plasmids of the outbreak strain is similar to pAA-type plasmids of EAEC strains, which contain aggregative adhesion fimbrial operons. The second putative plasmid harbors genes for extended-spectrum β-lactamases. This type of plasmid is widely distributed in pathogenic E. coli strains. A significant difference of the E. coli GOS1 and GOS2 genomes to those of EAEC strains is the presence of a prophage encoding the Shiga toxin, which is characteristic for enterohemorrhagic E. coli (EHEC) strains. The unique combination of genomic features of the German outbreak strain, containing characteristics from pathotypes EAEC and EHEC, suggested that it represents a new pathotype Entero-Aggregative-Haemorrhagic E scherichia c oli (EAHEC).     

Comparative evaluation of ethanol production by xylose-fermenting yeasts presented high xylose concentrations

Summary Three strains ofPichia stipitis and three ofCandida shehatae were compared withPachysolen tannophilus in their abilities to ferment xylose at concentrations as high as 200 g/L when subjected to both aerobic and microaerophilic conditions. Evaluations based on accumulated ethanol concentrations, ethanol productivities, xylose consumption, and ethanol and xylitol yields were determined from batch culture time courses. Of the strains considered,P.stipitis NRRL Y-7124 seemed most promising since it was able to utilize all but 7 g/L of 150 g/L xylose supplied aerobically to produce 52 g/L ethanol at a yield of 0.39 g per gram xylose (76% of theoretical yield) and at a rate comparable to the fastest shown byC.shehatae NRRL Y-12878. For all strains tested, fermentation results from aerobic cultures were more favorable than those from microaerophilic cultures.The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Fermentation of cellobiose and wood sugars to ethanol byCandida shehatae andPichia stipitis

Summary Three pentose fermenting yeast strains ofCandida shehatae and three ofPichia stipitis were examined for their ability to produce ethanol from cellobiose and from sugars liberated by hydrolysis of lignocellulosic biomass. All of thePichia strains tested produced some ethanol;P. stipitis CBS 5776 gave the highest yield: 10.3 g/L on complete fermentation of 25 g/L cellobiose within 48 hours. This yeast also produced considerably more ethanol from the wood sugar mixture.     

Different temperature profiles of enzyme secretion by two common strains ofTrichoderma reesei

Summary We have investigated the effects of high and low temperature on the synthesis and secretion of cellulases and other enzymes by two common and readily available strains ofTrichoderma reesei. While some effects were similar in both strains QM9414 and RUT-C30 (a reduction in cellulase production but stimulation of xylanase production at high temperature, and alterations in expression of the cellulase complex at low temperature), some specific differences between the strains were determined, most significantly an enhanced specific secretion rate (secretion/growth) at low growth temperature for QM9414.     

New yeast strains for alcoholic fermentation at higher sugar concentration

Summary New yeast strains for alcoholic fermentation were isolated from samples collected from Brazilian alcohol factories at the end of the sugar cane crop season. They were selected by their capacity of fermenting concentrated sugar cane syrup as well as high sucrose concentrations in synthetic medium with a conversion efficiency of 89–92%. The strains were identified asSaccharomyces cerevisiae.     

Foaming and enzyme activity in fungal cultures grown on sugar beet cosette

Summary Enzyme synthesis, foaming behaviour and its effects were studied using two common cellulolytic fungi;Trichoderma reesei andSporotrichum pulverulentum in a medium containing sugar beet cosette as a cellulosic substrate. Cellulase enzyme activities in the culture broth were found to be higher than the enzyme activities in natural and experimentally forced foam layers.     

Screening of yeast strains capable of hyperproducing amylolytic enzymes

Summary Fifteen strains of yeast, which produced an extracellular amylolytic enzymes, were isolated from nature. One of them produced more than 100 times the enzyme activity in comparison with the 14 strains and the extremely hyperproducing strain of yeast was identified asCandida sp. 347. Paper chromatograms of the amylolytic enzyme demonstrated activity of amyloglucosidase. The optimum pH for activity of the enzyme was 5.5–6.0 and optimum temperature was 60°C.     

Production of glucose isomerase by different strains ofStreptomyces

Summary The glucose isomerase activity ofStreptomyces haeochromogenes strains 1 and 2 varies considerably with the assay conditions (pH, glucose concentration,etc.). Nine other species of streptomyces were tested under conditions optimal forS.phaeochromogenes 2. The highest enzyme activity was found inS.nigrificans 3014.     

Production and localization of cellulases and β-glucosidase from the thermophilic fungusThielavia terrestris

Summary The enzyme production and localization ofThielavia terrestris strains C464 and NRRL 8126 were compared to determine their optimum temperature and pH for cellulase activity. High levels of intracellular -glucosidase activity were detected in the former strain. The intracellular -glucosidase of both strains were more thermostable than the extracellular enzyme; the half life ofT.terrestris (C464) endoglucanase activity at 60°C was greater than 96 hrs.     

Transformation of white spruce and other conifer species byAgrobacterium tumefaciens

Studies of the ability ofAgrobacterium to transform white spruce (Picea glauca), Engelmann spruce (P. engelmanni), Sitka spruce (P. sitchensis) and Douglas-fir (Pseudotsuga menziesii) showed frequencies of gall formation from 0–80% depending upon the strain ofAgrobacterium, and the conifer species. Thirty sixA. tumefaciens strains and oneA. rhizogenes strain were tested on 6 month old white spruce seedlings. NineA. tumefaciens strains induced gall formation on more than 50% of the inoculated trees and at greater than 10% of the inoculated sites. One strain, B2/74 gave rise to galls at 28% of the inoculated sites on white spruce and induced the highest overall frequency of gall formation on all the conifer species tested. Relative frequency of gall formation was consistent among species, although the overall frequency was much higher on Douglas-fir. Of the well characterized strains for which disarmed derivatives are available only A281 (carrying the supervirulent tumor inducing plasmid, pTiBo542) gave efficient transformation. Stable integration of T-DNA encoded genes has been confirmed by the expression of opine synthesis and hormone autonomous growth. The transfer and long-term stable expression of kanamycin resistance and firefly luciferase activity using binary vector systems was also achieved.     

Transformation ofBacillus subtilis with the treatment by alkali cations

Summary ExposingBacillus subtilis cultures to high concentrations of alkali cations, especially K⁺, allows efficient transformation by plasmids. The method allows transformation with unfractionated plasmid DNA, monomeric plasmid DNA as well as linear plasmid DNA.B. subtilis strains, not amenable to natural transformation, were also transformed by the present method.     

Genotypic and phenotypic correlationships among some strains ofLactobacillus helveticus

Summary Evidence for the presence of extrachromosomal elements inLactobacillus helveticus ATCC 15009 and the absence of plasmid DNA in two other strains ofL. helveticus is reported. These three strains did not show any difference in regard to lactose metabolism, proteolytic activity, and antibiotic resistance or in N-acetyl-D-glucosamine fermentation. The only difference found is a higher resistance to arsenate forL. helveticus ATCC 15009, suggesting linkage of this resistance to plasmids present in this strain.     

Extracts of Marine cyanobacteria stimulated somatic embryogenesis of Daucus carota L.

Twenty five strains of marine cyanobacteria were screened for their ability to promote carrot somatic embryogenesis. Hot water extracts prepared from 21 of these strains promoted plantlet formation. Extracts from four strains increased plantlet numbers to an average of over 3.7-fold. Dialysates and nondialysates of each of these extracts also increased plantlet formation. For extracts from filamentous cyanobacteria, Nostoc sp. and Anabaena sp., dialysate was more effective (4.2-fold increase) than nondialysate (3.0-fold increase), whereas for unicellular strains Synechococcus sp. and Xenococcus sp., nondialysate was more effective (5.2-fold increase) than the dialysate (3.2-fold increase). These cyanobacterial extracts also promoted embryolike structure formation from two-year old carrot cell cultures which were unable to produce plantlets using the usual methods. Here, we demonstrate the existence in marine cyanobacterial extracts of low and high molecular weight factors which strongly promote somatic embryogenesis in carrot cell cultures.Abbreviations MS Murashige and Skoog medium - 2, 4-D 2, 4-dichlorophenoxyacetic acid - PCV packed cell volume     

Determination of population balances in a mixed culture by specific cell adhesion

Summary Specific cell adhesion can be used to monitor the population balance in a mixed culture. A mixture of twoEscherichia coli strains were separated and monitored based on their different expression of thelamB protein. The results are compared to those obtained by differential plate counts.