摘要:

Cell-bound and extracellular acid and alkaline phosphatase activity have been studied inMyxococcus xanthusstrains DK101, DK1050, DK2834, and DK2836. Both phosphatases were released into a liquid medium during vegetative growth and the levels were similar in all strains. On solid media,M.xanthusDK101 showed maximum activity at the end of the developmental process, when mature myxospores appeared. An increase in phosphatase activity was also observed in glycerol-induced myxospores. A transitory increase in phosphatase activity occurred during the germination of both glycerol-induced and fruiting-body myxospores, although the activity of both phosphatases in fruiting-body myxospores was greater than that in glycerol-induced ones.Key words: acid phosphatase, alkaline phosphatase,Myxococcus xanthus.

ISSN:0008-4166    

DOI:10.1139/m91-011

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

Two cultures ofThiobacillus ferrooxidansenriched from Indian mine samples and grown autotrophically on FeSO4– basal salts medium for periods ranging from several months to years contained acidophilic, heterotrophic bacterial contaminants. The heterotrophs (strains KM2 and H8) were isolated by selective growth in a mineral salts – glucose – yeast extract medium of pH 3 and were purified as single colonies on an agarose medium. Mannose, galactose, sucrose, lactose, citrate, mannitol, and glycerol supported the growth of these strains in the presence of yeast extract. The heterotrophs grew poorly or failed to grow in media without yeast extract. They could not grow autotrophically with Fe2+, or with sulfur and its oxidizable derivatives, as the sole source of energy. Although they exhibited many characteristics of the genusAcidiphilium, they differed fromAcidiphilium cryptumand other species of this genus in some physiological properties, notably in their ability to grow at higher glucose (5%, w/v) and Mn2+(20 mM) concentrations. The G+C mol% contents (58.8 and 60.2) of strains KM2 and H8, respectively, determined from melting temperature (Tm) values were close to that ofA.cryptum(62.7%). Strains KM2 and H8 showed 70–80% DNA homology with each other and about 60% withA.cryptum. All of the strains, includingA.cryptum, responded similarly to several metal ions and antibiotics. SDS–PAGE of whole-cell proteins exhibited striking similarity between these two isolated strains, which were unlike that ofA.cryptum. The strains were also agglutinated with a few common lectins and differed strongly fromA.cryptumin respect to wheat-germ agglutinin and concanavalin A. Considering all these characteristics, we propose that strains KM2 and H8 be designated as a new species:Acidiphilium symbioticum. The type strain ofA.symbioticumis strain KM2 (= MTCC 566).Key words:Acidiphilium symbioticum,Acidiphilium cryptum,Thiobacillus ferrooxidans, acidophilic bacteria.

ISSN:0008-4166    

DOI:10.1139/m91-012

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

A 7.7-kilobase (kb)Penicillium urticaegenomic DNA fragment containing the 3′ terminus of the 6-methylsalicylic acid polyketide synthetase gene was cloned using a 41-mer mixed oligodeoxynucleotide probe which was based on a cyanogen bromide cleavage peptide of 35 amino acids obtained from pure synthetase. Nucleotide sequence analysis of a 2.2-kb region of the cloned fragment revealed a large open reading frame of 1866 bases which was devoid of introns and which corresponded to amino acids of the carboxyl terminus of the enzyme. This was followed by a putative transcription termination–polyadenylation signal. A putative acyl carrier protein domain at the 3′ terminus was preceded by a β-ketoreductase domain. These functionalities were identified by amino acid sequences known to be characteristic of the active sites of fatty acid synthetase functional domains. Their relative positions contrast with those in yeast andP.urticaefatty acid synthetase genes where the two functional domains are located at the 5′ terminus and in reverse order. Furthermore, amino acid sequence identities indicated a striking homology with vertebrate rather than either yeast orP.urticaefatty acid synthetases.Key words: multifunctional enzyme, mycotoxin,Pencillium, polyketide synthetase, secondary metabolism.

ISSN:0008-4166    

DOI:10.1139/m91-013

出版商:NRC Research Press    

年代:1991

数据来源: NRC