Escherichia coli is the most completely characterized prokaryotic model organism and one of the dominant indicator organisms for food and water quality testing, yet comparatively little is known about the structure of E. coli populations in their various hosts. The diversities of E. coli populations isolated from the feces of three host species (human, cow, and horse) were compared by two subtyping methods: ribotyping (using HindIII) and antibiotic resistance analysis (ARA). The sampling effort required to obtain a representative sample differed by host species, as E. coli diversity was consistently greatest in horses, followed by cattle, and was lowest in humans. The diversity of antibiotic resistance patterns isolated from individuals was consistently greater than the diversity of ribotypes. E. coli populations in individuals sampled monthly, over a 7-to 8-month period, were highly variable in terms of both ribotypes and ARA phenotypes. In contrast, E. coli populations in cattle and humans were stable over an 8-h period. Following the cessation of antibiotic therapy, the E. coli population in the feces of one human experienced a rapid and substantial shift, from a multiply antibioticresistant phenotype associated with a particular ribotype to a relatively antibiotic-susceptible phenotype associated with a different ribotype. The high genetic diversity of E. coli populations, differences in diversity among hosts, and temporal variability all indicate complex population dynamics that influence the usefulness of E. coli as a water quality indicator and its use in microbial source tracking studies.The structure of Escherichia coli populations influences several aspects of public health. Pathogenic subtypes of E. coli are known to cause illness around the world (18), and an increased understanding of the genetic variability of populations in animal reservoirs can inform epidemiological studies. E. coli is also one of the standard indicator organisms for fecal pollution in environmental waters (1). The natural host range of E. coli includes all warm-blooded animals, some cold-blooded animals (12), and environmental reservoirs, such as sediments (2, 32) and free-living strains (24); therefore, the source of fecal pollution in water bodies is often ambiguous. Knowledge of indicator organism source is necessary for risk assessment and remediation of polluted waters, including application, such as total maximum daily load assessment. Consequently, the field of microbial source tracking (MST), which seeks to determine the origin of fecal material in water, has emerged (4, 7, 10, 14, 23, 31, 35).Many microbial source tracking methods rely on the premise that, in their gastrointestinal tracts, animal species contain distinct subtypes of E. coli that are shed in their feces. Matching the subtypes of E. coli identified in polluted watersheds to those isolated from known sources would hypothetically allow the identification of the source of the pollution (28). Many MST methods require a library of E. coli subtypes isolated fr...

Forty four marine actinomycetes of the family Microccocaceae isolated from sponges collected primarily in Florida Keys (USA) were selected from our strain collection to be studied as new sources for the production of bioactive natural products. A 16S rRNA gene based phylogenetic analysis showed that the strains are members of the genera Kocuria and Micrococcus. To assess their biosynthetic potential, the strains were PCR screened for the presence of secondary metabolite genes encoding nonribosomal synthetase (NRPS) and polyketide synthases (PKS). A small extract collection of 528 crude extracts generated from nutritional microfermentation arrays was tested for the production of bioactive secondary metabolites against clinically relevant strains (Bacillus subtilis, methicillin-resistant Staphylococcus aureus (MRSA), Acinetobacter baumannii and Candida albicans). Three independent isolates were shown to produce a new anti-MRSA bioactive compound that was identified as kocurin, a new member of the thiazolyl peptide family of antibiotics emphasizing the role of this family as a prolific resource for novel drugs.

Stimulated production of reactive oxygen species (ROS) by plasma membrane-associated nicotinamide adenine dinucleotide phosphate oxidases (Nox) in non-phagocytic cells regulates a number of biological processes including growth, vessel tone, and oxygen sensing. The purpose of this study was to investigate H 2 O 2 -stimulated ROS production in primary adult cardiac fibroblasts (CF). Results demonstrate that CF express an H 2 O 2 -inducible oxidant generating system that is inhibitable by diphenylene iodonium (DPI) and sensitive to antioxidants. In addition to H 2 O 2 , generation of ROS was stimulated potently by 1-oleoyl-2-acetyl-sn-glycerol (OAG) and arachidonic acid (AA) in a protein kinase C-independent manner. Pretreatment with arachidonyl trifluoromethyl ketone was nearly as effective as DPI at reducing H 2 O 2 -and OAG-stimulated oxidant generation indicating a central role for phospholipase A 2 (PLA 2 ) in this signaling pathway. Co-stimulation with H 2 O 2 and OAG did not increase ROS generation as compared to OAG alone suggesting both agonists signal through a shared, rate-limited enzymatic pathway involving PLA 2 . Co-stimulation with H 2 O 2 and AA had additive effects indicating these two agonists stimulate oxidant production through a parallel activation pathway. Reverse transcriptase-coupled polymerase chain reaction and Western blotting demonstrate primary cardiac fibroblasts express transcripts and protein for Nox4, p22, p47, and p67 phox. Transfections with Nox4 small inhibitory ribonucleic acid oligonucleotides or p22 phox antisense oligonucleotides significantly downregulated stimulated Nox activity. Inhibitors of nitric oxide synthases were without effect. We conclude adult CF express Nox4/p22 phox-containing oxidant generating complex activated by H 2 O 2 , OAG, and AA through a pathway that requires activation of PLA 2 .

A new thiazolyl peptide, kocurin (1), was isolated from culture broths of a marine-derived Kocuria palustris. Its structural elucidation was accomplished using a combination of spectroscopic and chemical methods, including HRMS, extensive 1D and 2D NMR analysis, MS/MS fragmentation, and chemical degradation and Marfey’s analysis of the resulting amino acid residues. The structure herein reported corrects that previously assigned to PM181104 (3). Kocurin displayed activity against methicillin-resistant Staphylococcus aureus (MRSA), with MIC values in the submicromolar range.

Increasing petroleum costs and climate change have resulted in microalgae receiving attention as potential biofuel producers. Little information is available on the diversity and functions of bacterial communities associated with biofuel-producing algae. A potential biofuel-producing microalgal strain, Nannochloropsis oceanica IMET1, was grown in Permian groundwater. Changes in the bacterial community structure at three temperatures were monitored by two culture-independent methods, and culturable bacteria were characterized. After 9 days of incubation, N. oceanica IMET1 began to aggregate and precipitate in cultures grown at 30°C, whereas cells remained uniformly distributed at 15°C and 25°C. The bacterial communities in cultures at 30°C changed markedly. Some bacteria isolated only at 30°C were tested for their potential for aggregating microalgae. A novel bacterium designated HW001 showed a remarkable ability to aggregate N. oceanica IMET1, causing microalgal cells to aggregate after 3 days of incubation, while the total lipid content of the microalgal cells was not affected. Direct interaction of HW001 and N. oceanica is necessary for aggregation. HW001 can also aggregate the microalgae N. oceanica CT-1, Tetraselmis suecica, and T. chuii as well as the cyanobacterium Synechococcus WH8007. 16S rRNA gene sequence comparisons indicated the great novelty of this strain, which exhibited only 89% sequence similarity with any previously cultured bacteria. Specific primers targeted to HW001 revealed that the strain originated from the Permian groundwater. This study of the bacterial communities associated with potential biofuel-producing microalgae addresses a little-investigated area of microalgal biofuel research and provides a novel approach to harvest biofuel-producing microalgae by using the novel bacterium strain HW001.