Attachment as a factor in the protection of Enterobacter cloacae from chlorination

Enterobacter cloacae attached to drinking water distribution particles was subjected to chlorination. Attachment resulted in the protection of these organisms from disinfection. This effect was found to be dependent upon both the level of chlorine in the system and attachment time. The results obtained in this study indicate that attached organisms may play an important role in coliform outbreaks.     

Attachment as a factor in the protection of Enterobacter cloacae from chlorination.

Enterobacter cloacae attached to drinking water distribution particles was subjected to chlorination. Attachment resulted in the protection of these organisms from disinfection. This effect was found to be dependent upon both the level of chlorine in the system and attachment time. The results obtained in this study indicate that attached organisms may play an important role in coliform outbreaks.     

Study of elastase-type activity in blister fluids of recessive dystrophic epidermolysis bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is characterized clinically by blister formation due to minor trauma and ultrastructurally by a progressive disappearance of anchoring fibrils at the dermoepidermal junction and of the oxytalan-type fibers which belong to the elastic fiber system. In this study, we determined the elastase-type activity in blister fluid obtained from 8 patients suffering from RDEB as compared to the suction fluid of experimental blisters in a healthy person and to the blister fluid of a patient suffering from epidermolysis bullosa simplex. One patient with dominant dystrophic epidermolysis of the albopapuloid type was also studied. Seven of the eight children with RDEB showed highly elevated values. The eighth child, treated with etretinate, as well as the patient suffering from dominant epidermolysis bullosa had moderately increased values. The determination of elastase-type activity in the blister fluid could therefore be useful to establish the differential diagnosis of recessive dystrophic epidermolysis bullosa.     

Enumeration of chlorine-stressed organisms with acridine orange 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (AOINT)

Direct microscopic enumeration ofEnterobacter cloacae with the acridine orange 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride technique (AOINT) was compared with spread plate counts on nonselective media to establish the usefulness of the former technique in the enumeration of chlorine-stressed cells. Results indicate that the techniques are comparable when the organisms are not stressed. However, AOINT is more sensitive than are plate counts in the detection of chlorine-stressed cells.     

The effect of cycloheximide on Euglena gracilis phenylalanyl-tRNA synthetases

The effect of cycloheximide on the chloroplastic, cytoplasmic and mitochondrial phenylalanyltransferRNA synthetases of Euglena gracilis was studied by growing both logarithmic and stationary phase cultures in the presence of the antibiotic. Enzyme activity was measured relative to untreated control cultures. At very low concentrations of cycloheximide (1 g/ml), all three log phase enzymes showed an increase in activity of 40–50%. At slightly higher concentrations (2.5 g/ml), the phenylalanyl-tRNA synthetase activities were comparable to those of the control cultures. At a cycloheximide concentration of 5g/ml the enzyme activities from stationary phase cultures showed only very slight decreases (5–20%). The cytoplasmic and mitochondrial enzymes behaved similarly in log phase cultures at this concentration. However, the chloroplastic phenylalanyl-tRNA synthetase from log phase cultures treated with 5g/ml cycloheximide showed a marked decrease in activity (70%). A further increase in antibiotic concentration to 10g/ml resulted in significant losses of activity of all three enzymes, from both growth stages. The implications of the data with regard to identification of the site(s) of chloroplast enzyme synthesis are discussed.     

Interactions between the diatom Thallasiosira pseudonanna and an associated pseudomonad in a mariculture system.

The marine diatom Thallasiosira pseudonanna (3H) and several bacteria associated with it were isolated from batch cultures at the University of Delaware mariculture facility. The interaction between the algae and each of the bacteria was investigated. One of the isolates, T827/2B (Pseudomonas sp.), was incapable of surviving in f/2 culture medium unless the algae were present. When the algae and T827/2B were grown together in the f/2 medium, the bacterial growth was stimulated and the algal growth was inhibited. Bacterial filtrate had a similar effect on the algae, indicating that the bacterial effect is an indirect one most likely resulting from the excretion of a harmful compound into the medium. Preliminary characterization of the material excreted by the bacteria indicates that it s proteinaceous in nature. The interactions observed does not fit into any single category of interactions but can be explained as a combination of competition and indirect parasitism.     

Sensitive fluorescence in situ hybridization signal detection in maize using directly labeled probes produced by high concentration DNA polymerase nick translation

The signal produced by fluorescence in situ hybridization (FISH) often is inconsistent among cells and sensitivity is low. Small DNA targets on the chromatin are difficult to detect. We report here an improved nick translation procedure for Texas red and Alexa Fluor 488 direct labeling of FISH probes. Brighter probes can be obtained by adding excess DNA polymerase I. Using such probes, a 30?kb yeast transgene, and the rp1, rp3 and zein multigene clusters were clearly detected.     

Biodeterioration of Mayan buildings at uxmal and tulum,Mexico

Uxmal and Tulum are two important Mayan sites in the Yucatan peninsula. The buildings are mainly composed of limestone and grey/black discoloration is seen on exposed walls and copious greenish biofilms on inner walls. The principal microorganisms detected on interior walls at both Uxmal and Tulum were cyanobacteria; heterotrophic bacteria and filamentous fungi were also present. A dark‐pigmented mitosporic fungus and Bacillus cereus, both isolated from Uxmal, were shown to be acidogenic in laboratory cultures. Cyanobacteria belonging to rock‐degrading genera Synechocystis and Gloeocapsa were identified at both sites. Surface analysis previously showed that calcium ions were present in the biofilms on buildings at Uxmal and Tulum, suggesting the deposition of biosolubilized stone. Apart from their potential to degrade the substrate, the coccoid cyanobacteria supply organic nutrients for bacteria and fungi, which can produce organic acids, further increasing stone degradation.