Exploring the operating factors controlling Kouleothrix (type 1851), the dominant filamentous bacterial population, in a full-scale A2O plant.

This study reveals that the abundance of the filament Kouleothrix (Eikelboom type 1851) correlated positively with poor settleability of activated sludge biomass in a Japanese full-scale nutrient removal wastewater treatment plant sampled over a one-year period. 16S rRNA amplicon sequence data confirmed that Kouleothrix was the dominant filament in the plant, with a relative abundance of 3.06% positively correlated with sludge volume index (SVI) (R = 0.691). Moreover, Kouleothrix (type 1851) appeared to form interfloc bridges, typical of bulking sludge, regardless of season. Together with earlier studies that indicated the responsibility of Kouleothrix (type 1851) on bulking events, these data suggest that their high relative abundances alone may be responsible for sludge bulking. 16S rRNA qPCR data for this filament showed changes in its relative abundance correlated with changes in several operational parameters, including mixed liquor temperature, sludge retention time, and suspended solids concentration, and it may be that manipulating these may help control Kouleothrix bulking.

Segregation and linkage analysis of 75 novel microsatellite DNA markers in pair crosses of Japanese abalone (Haliotis discus hannai) using the 5'-tailed primer method.

We present novel microsatellite markers of the Japanese abalone (Haliotis discus hannai) for general mapping studies in this species. A total of 75 microsatellite markers were developed, and the allele-transmission patterns of these markers were studied in three families generated by pair crosses. For allele scoring, we employed the 5'-tailed primer polymerase chain reaction (PCR) technique, which substantially reduces the cost for fluorescent labeling of primers. Of the 225 possible marker-family combinations (75 markers x 3 families), 18 cases of informative null-allele segregation were inferred. When such null-allele segregations were allowed, more than 70% of the 75 markers in the families turned out to be markers with an expected segregation ratio of 1:1:1:1, allowing maximal exploitation of the codominant nature of microsatellite markers. There were 16 instances of segregation distortion at the 5% significance level. The test for independence of segregation assigned the 75 markers into 17 linkage groups, which is in close agreement with the haploid chromosome number of H. discus hannai (n = 18). Six markers could not be placed into any linkage group. We suggest that these markers could help construct a H. discus hannai linkage map.

Inheritance of microsatellite DNA markers in the Pacific abalone Haliotis discus hannai.

Microsatellite markers have been developed for a variety of abalones, and locus-specific homozygote excesses at population level have been recorded for microsatellite loci. To ascertain whether null alleles exist at microsatellite loci in the Pacific abalone, we studied the mode of inheritance of 7 microsatellite loci in 4 families with a reciprocal cross of 2 females x 2 males. All loci segregated codominantly, but only 3 loci ( Hdh1321, Hdh78, and Hdd108C) conformed to Mendelian segregation and can be used for parental analysis and population genetic studies. When null alleles were considered, 2 loci (Hdh1761 and Hdh1457) confirmed Mendelian expectations in all families, while the remaining 2 loci (Hdd114B and Hdd229) showed deviation from Mendelian segregation in at least one family even though null alleles were considered. These results indicated the need to test the inheritance pattern for microsatellite markers in abalones before using them for population genetic of parentage analysis.