On assessing individual differences in rumination on sadness.

The Rumination on Sadness Scale (RSS), an individual-difference measure of rumination on sadness, was developed as an alternative to the Ruminative Responses scale of the Response Styles Questionnaire (RRRSQ; Nolen-Hoeksema & Morrow, 1991). Research has shown the RRRSQ to consist of multiple, not highly intercorrelated factors; only I factor explicitly addresses rumination. In Study 1, a 1-factor solution to a principal components analysis was shown to hold for responses to the RSS. The RSS was also shown to be reliable. In Study 2, convergent and discriminant validity of the RSS were assessed. In Study 3, individuals with high RSS scores exhibited more distress regarding current concerns with the introduction of a delay period (to allow them to ruminate) after a sad mood induction.

Effects of the Fusarium spp. mycotoxins fusaric acid and deoxynivalenol on the growth of Ruminococcus albus and Methanobrevibacter ruminantium.

The Fusarium spp. mycotoxins fusaric acid and deoxynivalenol (DON) were tested for antimicrobial activity against Ruminococcus albus and Methanobrevibacter ruminantium. The growth of both organisms was inhibited by fusaric acid as low as 15 micrograms/mL (84 microM) but not by DON, at levels as high as 100 micrograms/mL (338 microM). No synergistic inhibitory effect was observed with DON plus fusaric acid. Neither organism was able to adapt to the fusaric acid and responses of each organism to the compound were different. The optical density (OD) maximum for R. albus, but not for M. ruminantium, was diminished after 28 days incubation at concentrations of fusaric acid below 240 micrograms/mL. Inhibition of R. albus started before significant growth had occurred, while M. ruminantium doubled twice before the onset of inhibition. Responses to picolinic acid, an analog of fusaric acid, were also dramatically different between the two microorganisms with M. ruminantium exhibiting a severe lag followed by a complete recovery of growth, while R. albus was only slightly inhibited with no lag. These results suggest that the mechanism of fusaric acid inhibition is specific to each microorganism. This is the first demonstration of the common mycotoxin fusaric acid inhibiting the growth of rumen bacteria.

Effects of polychlorinated biphenyl congener concentration and sediment supplementation on rates of methanogenesis and 2,3,6-trichlorobiphenyl dechlorination in an anaerobic enrichment.

We have employed a method of enrichment that allows us to significantly increase the rate of reductive polychlorinated biphenyl (PCB) dechlorination. This method shortens the time required to investigate the effects that culture conditions have on dechlorination and provides an estimate of the potential activity of the PCB-dechlorinating anaerobes. The periodic supplementation of sterile sediment and PCB produced an enhanced, measurable, and sustained rate of dechlorination. We observed volumetric rates of the dechlorination of 2,3,6-trichlorobiphenyl (2,3,6-CB) to 2,6-dichlorobiphenyl (2,6-CB) of more than 300 mumol liter day when the cultures were supplemented daily. A calculation of this activity that is based on an estimate of the number of dechlorinating anaerobes present indicates that 1.13 pmol of 2,3,6-CB was dechlorinated to 2,6-CB day bacterial cell. This rate is similar to that of the reductive dechlorination of 3-chlorobenzoate by Desulfomonile tiedjei. Methanogenesis declined from 585.3 to 125.9 mumol of CH(4) liter day, while dechlorination increased from 8.2 to 346.0 mumol of 2,3,6-CB dechlorinated to 2,6-CB liter day.

Subculturing of a polychlorinated biphenyl-dechlorinating anaerobic enrichment on solid media.

An anaerobic culture capable of dechlorinating polychlorinated biphenyls was subcultured under strict anaerobic conditions on solid media containing sterilized river sediment. The dechlorination activity was transferred as a bacterial colony on a solid medium three times. After two transfers on solid medium, the culture was no longer methanogenic but still dechlorinated a mixture of tri- and tetrachlorobiphenyls. This demonstrates that anaerobic bacteria are responsible for the polychlorinated biphenyl dechlorination and can be grown without polychlorinated biphenyl on solid media.

Monohydroxylation of phenol and 2,5-dichlorophenol by toluene dioxygenase in Pseudomonas putida F1.

Pseudomonas putida F1 contains a multicomponent enzyme system, toluene dioxygenase, that converts toluene and a variety of substituted benzenes to cis-dihydrodiols by the addition of one molecule of molecular oxygen. Toluene-grown cells of P. putida F1 also catalyze the monohydroxylation of phenols to the corresponding catechols by an unknown mechanism. Respirometric studies with washed cells revealed similar enzyme induction patterns in cells grown on toluene or phenol. Induction of toluene dioxygenase and subsequent enzymes for catechol oxidation allowed growth on phenol. Tests with specific mutants of P. putida F1 indicated that the ability to hydroxylate phenols was only expressed in cells that contained an active toluene dioxygenase enzyme system. 18O2 experiments indicated that the overall reaction involved the incorporation of only one atom of oxygen in the catechol, which suggests either a monooxygenase mechanism or a dioxygenase reaction with subsequent specific elimination of water.

Plasmid pCBI carries genes for anaerobic benzoate catabolism in Alcaligenes xylosoxidans subsp. denitrificans PN-1.

Pseudomonas sp. strain PN-1 is reclassified as Alcaligenes xylosoxidans subsp. denitrificans PN-1. Strain PN-1 is a gram-negative, rod-shaped organism, is motile by means of lateral flagella, is oxidase positive, and does not ferment sugars. Plasmid pCBI, carrying genes for the anaerobic degradation of benzoate in strain PN-1, is 17.4 kilobase pairs in length and is transmissible to a number of denitrifying Pseudomonas aeruginosa and Pseudomonas stutzeri strains. A restriction endonuclease map was constructed.