Oxygen transfer rates in shaken culture vessels from Fernbach flasks to microtiter plates.

By a sulfite oxidation method, oxygen transfer rates (OTRs) were determined in 11 types of culture vessels from 2.8-L Fernbach (FB) flasks to 96-, 48-, and 24-well square deepwell microtiter plates (MTPs). OTRs ranged from 140 mM/h in 250-mL Ultrayield™ flasks shaken at 300 rpm with a 50 mm diameter shaker throw to 5 mM/h in unbaffled FBs shaken at 200 rpm with a 25 mm throw.

Metabolic engineering of Escherichia coli for industrial production of glucosamine and N-acetylglucosamine.

Glucosamine and N-acetylglucosamine are currently produced by extraction and acid hydrolysis of chitin from shellfish waste. Production could be limited by the amount of raw material available and the product potentially carries the risk of shellfish protein contamination. Escherichia coli was modified by metabolic engineering to develop a fermentation process.

The pathway of L-ascorbic acid biosynthesis in the colourless microalga Prototheca moriformis.

When mutant strain UV77-247 of Prototheca moriformis Kruger was fed d-[1-13C]Glc, it synthesized l-ascorbic acid (AA) with approximately three-quarters of the label at the C-1 position and the remaining label at the C-6 position, showing that AA is made by a non-inversion (retention) pathway, i.e. C-1 of Glc becomes C-1 of AA.

Extracellular production of L-ascorbic acid by Chlorella protothecoides, Prototheca species, and mutants of P. moriformis during aerobic culturing at low pH.

Nine strains of Chlorella protothecoides and 43 strains representing the five species of Prototheca were screened in flask culture for their ability to synthesize L-ascorbic acid (AA). Ascorbic acid was detected in all strains, ranging from 4.8 to 0.

Branched DNA amplification multimers for the sensitive, direct detection of human hepatitis viruses.

Branched oligonucleotides (bDNA) have been synthesized containing a unique primary segment and a set of identical secondary fragments covalently attached to the primary sequence through branch points. The primary sequence is designed to hybridize (directly or indirectly) to a target nucleic acid, such as hepatitis B virus (HBV) or hepatitis C virus (HCV) genomic DNA or RNA, respectively. The secondary fragments are used to direct the binding of multiple copies of a small oligonucleotide labelled with alkaline phosphatase.

Rapid nucleic acid assay for detection of bacteria with tetM-mediated tetracycline resistance.

A novel nucleic acid assay has been developed to screen bacterial populations for the presence of the tetM structural gene. The method involves the specific hybridization of several synthetic oligonucleotides to the gene in a crude bacterial lysate solution. As few as 1.

Application of a rapid non-radioisotopic nucleic acid analysis system to the detection of sexually transmitted disease-causing organisms and their associated antimicrobial resistances.

We devised a versatile method for detecting nucleic acids in crude lysates of biological samples. A controlled network of nucleic acid hybrids composed of the target fragment, several oligonucleotide probes, branched DNA amplifiers, and labeled oligonucleotides is produced on a solid phase to ultimately incorporate 60 to 300 molecules of alkaline phosphatase, which are detected with a chemiluminescent substrate. The visible light output can be recorded on a luminometer or on instant black-and-white film.

A rapid chemiluminescent DNA hybridization assay for the detection of Chlamydia trachomatis.

With an estimated 3-4 million new cases per year, human infections from Chlamydia trachomatis are probably the most prevalent sexually transmitted disease (STD) in the United States. Diagnosis of Chlamydia is usually conducted by tissue culture methods. Direct immunofluorescence and ELISA tests have become available, but there remains a need for a test with better specificity and sensitivity.

A comparison of non-radioisotopic hybridization assay methods using fluorescent, chemiluminescent and enzyme labeled synthetic oligodeoxyribonucleotide probes.

N4-[N-(6-trifluoroacetylamidocaproyl)-2-aminoethyl]-5'-O-dimethoxy trityl -5-methyl-2'-deoxycytidine-3'-N,N-diisopropyl-methylphosphoramidite++ + has been synthesized. This N4-alkylamino deoxycytidine derivative has been incorporated into oligonucleotide probes during chemical DNA synthesis. Subsequent to deprotection and purification, fluorescent (fluorescein, Texas Red and rhodamine), chemiluminescent (isoluminol), and enzyme (horseradish peroxidase, alkaline phosphatase) labels have been specifically incorporated.

A novel method for the rapid detection of specific nucleotide sequences in crude biological samples without blotting or radioactivity; application to the analysis of hepatitis B virus in human serum.

The detection of a little as 0.2 pg (60,000 molecules) of hepatitis B viral (HBV) DNA in human serum samples in 4 h has been demonstrated using a solution-hybridization and bead-capture method. An amplification method based on chemically crosslinked oligodeoxyribonucleotides was coupled with a horseradish peroxidase-labeling scheme for the ultimate detection of the analyte.