Death of the Escherichia coli K-12 strain W3110 in soil and water.

Whether Escherichia coli K-12 strain W3110 can enter the "viable but nonculturable" state was studied with sterile and nonsterile water and soil at various temperatures. In nonsterile river water, the plate counts of added E. coli cells dropped to less than 10 CFU/ml in less than 10 days. Acridine orange direct counts, direct viable counts, most-probable-number estimates, and PCR analyses indicated that the added E. coli cells were disappearing from the water in parallel with the number of CFU. Similar results were obtained with nonsterile soil, although the decline of the added E. coli was slower. In sterile water or soil, the added E. coli persisted for much longer, often without any decline in the plate counts even after 50 days. In sterile river water at 37 degrees C and sterile artificial seawater at 20 and 37 degrees C, the plate counts declined by 3 to 5 orders of magnitude, while the acridine orange direct counts remained unchanged. However, direct viable counts and various resuscitation studies all indicated that the nonculturable cells were nonviable. Thus, in either sterile or nonsterile water and soil, the decline in plate counts of E. coli K-12 strain W3110 is not due to the cells entering the viable but nonculturable state, but is simply due to their death.

Potential for gene transfer from recombinant Escherichia coli K-12 used in bovine somatotropin production to indigenous bacteria in river water.

This study examined the transfer of the plasmid pBGH1, an expression vector for bovine somatotropin (BST), from Escherichia coli K-12 strain W3110G [pBGH1] to indigenous microorganisms present in flasks containing Missouri River water. Strain LBB269 is a nalidixic acid-resistant derivative of W3110G which was used as a plasmid-free control strain in these studies. Water samples were inoculated with strains W3110G [pBGH1] and LBB269; after 21 days of incubation the number of viable colony-forming units (CFU) of W3110G [pBGH1] and LBB269 were reduced from an initial level of about 1 x 10(7) CFU per ml to less than 1 CFU per 100 ml. At this time indigenous microbes resistant to both ampicillin and tetracycline (the antibiotic resistance markers on pBGH1) were isolated from 100 ml of water from each of the flasks inoculated with either strain W3110G [pBGH1] or LBB269. Plasmid DNA was isolated from these organisms and examined for sequences containing the gene for BST from pBGH1, using a polymerase chain reaction (PCR) assay. As expected, the day 0 sample from the flask inoculated with E. coli K-12 strain W3110G [pBGH1] gave a positive PCR response and the day 0 sample from the flask inoculated with E. coli K-12 strain LBB269 gave a negative PCR response. All of the day 21 samples containing indigenous microbes isolated from flasks that were inoculated with either W3110G [pBGH1] or LBB269 were negative in the PCR assay, indicating that the target sequence from pBGH1 was not present in any of these indigenous microorganisms.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of mode of presentation on comprehension of below average, average and above average readers.

300 subjects in Grades 4, 5, and 6 were randomly blocked into three conditions (reading only, listening only, or reading and listening) according to reading level (above average, average, and below average). The subjects were presented a 1500-word social studies passage and required to answer 25 multiple-choice questions concerning that passage. A 3 (grade) by 3 (reading level) by 3 (exposure condition) analysis of variance showed better performance by above average readers, poorest by those below average. Reading and listening and reading only gave higher scores.

Contrasting adaptive behavior ratings of male and female institutionalized residents across two settings.

Twenty-two mentally retarded male and 22 retarded female residents from a state institution in central Ohio were compared on Adaptive Behavior Scale, Part Two, ratings across two settings (cottage and classroom). A multivariate analysis of variance did not reveal an overall interaction of sex and setting nor an overall effect for sex differences. Results did indicate a significant overall effect for setting. Significant differences were found in the following domains: Rebellious Behavior, Stereotyped Behavior and Odd Mannerisms, Unacceptable Vocal Habits, Hyperactive Tendencies, and Psychological Tendencies. Higher scores (negative direction) were noted in the classroom setting.