Flagellin gene structure offlaA andflaB and adjacent gene loci in urease-positive thermophilicCampylobacter (UPTC)

Comparative genomics of the Campylobacter lari group

The Campylobacter lari group is a phylogenetic clade within the epsilon subdivision of the Proteobacteria and is part of the thermotolerant Campylobacter spp., a division within the genus that includes the human pathogen Campylobacter jejuni. The C. lari group is currently composed of five species (C. lari, Campylobacter insulaenigrae, Campylobacter volucris, Campylobacter subantarcticus, and Campylobacter peloridis), as well as a group of strains termed the urease-positive thermophilic Campylobacter (UPTC) and other C. lari-like strains. Here we present the complete genome sequences of 11 C. lari group strains, including the five C. lari group species, four UPTC strains, and a lari-like strain isolated in this study. The genome of C. lari subsp. lari strain RM2100 was described previously. Analysis of the C. lari group genomes indicates that this group is highly related at the genome level. Furthermore, these genomes are strongly syntenic with minor rearrangements occurring only in 4 of the 12 genomes studied. The C. lari group can be bifurcated, based on the flagella and flagellar modification genes. Genomic analysis of the UPTC strains indicated that these organisms are variable but highly similar, closely related to but distinct from C. lari. Additionally, the C. lari group contains multiple genes encoding hemagglutination domain proteins, which are either contingency genes or linked to conserved contingency genes. Many of the features identified in strain RM2100, such as major deficiencies in amino acid biosynthesis and energy metabolism, are conserved across all 12 genomes, suggesting that these common features may play a role in the association of the C. lari group with coastal environments and watersheds.

An investigation into the kinetics and mechanism of the removal of cyanobacteria by extract of Ephedra equisetina root

An aqueous extract of Ephedra equisetina root was found to induce cyanobacterial cell death. The extract displayed no negative effects on the fish populations but instead, improved the habitat conditions for the growth of macrophytes, zooplankton and bacteria because the inhibiting effects of the extracts on cyanobacteria helped clear up the water column. The removal kinetics of cyanobacteria by E. equisetina extract appears to be a first order process with the rate constant being extract-dose-dependent. Compounds including the flavonoids found in E. equisetina root kill the cyanobacteria in vitro at a dose of 5.0 µg extract per 100 mL water or above. The extract constituents act to disrupt the thylakoid membrane, interrupt the electronic transport, decrease the effective quantum yield, and eventually lead to the failure of photosynthesis in Microcystis aeruginosa. This study presents an easily-deployed, natural and promising approach for controlling cyanobacterial blooms as an emergency measure, and also provides insight into the dynamics and mechanism of the extract consisting of multiple compounds synergistically removing algae.

Phylogenetic analysis of urease-positive thermophilic Campylobacter (UPTC) strains based on the molecular characterization of the flaA gene

Molecular cloning, nucleotide sequencing, and characterization of the flaA gene from additional isolates of urease-positive thermophilic Campylobacter (UPTC) were performed. These isolates were obtained from the natural environment in Northern Ireland (n = 9 from mussels) and in England (n = 1 from sea water). All isolates carried the shorter flaA gene, [open reading frames (ORFs), 1,461 to 1,503 base pairs], without any internal termination codons, and did not carry any flaA pseudogenes. The UPTC isolates were well discriminated by the neighbor joining (NJ) phylogenetic tree constructed based on the putative flaA genes ORFs nucleotide sequence information. In addition, the NJ tree constructed based on the flaA-short variable region sequence information discriminated the Campylobacter lari isolates with a similar degree of discrimination power.

Evaluating adsorption and biodegradation mechanisms during the removal of microcystin-RR by periphyton

Microcystin-RR (MCRR) is among the cyanobacterial toxins of significant concern due to their negative effects on water quality and human health. In this study, periphyton dominated by bacteria and diatoms was applied to remove MCRR from water. The maximum removal rate of MCRR by periphyton was observed in the first day (the latent adaptation period). Within this period, 85.2%, 73.3%, 83.5%, and 86.5% of the total MCRR removed (through adsorption and biodegradation) was by the adsorption of periphyton when the periphyton biomasses were 1.32 g, 3.96 g, 6.60 g, and 9.24 g, respectively. The amount of MCRR adsorbed increased with the increasing ratio of periphyton biomass to MCRR in solution. The adsorption process fitted well to the Freundlich, Langmuir, and Dubinin-Radushkevich (D-R) models, implying that the bioadsorption process has mechanistic relevance. The MCRR adsorption by periphyton is physical in nature and thermodynamically spontaneous. This study provided strong evidence that adsorption was the main mechanism for the removal of MCRR and other microcystins by periphyton and similar microbial aggregates in the latent adaptation period. Thereafter, biodegradation of periphyton dominated the toxin removal process. These results show that periphyton can be employed for an environmentally benign and effective solution for MCRR removal.