Carotenoids have been used for many years as an added pigment to enhance egg yolk color. One such carotenoid, astaxanthin, has a strong antioxidant activity and is produced by several microorganisms, including the bacterium Paracoccus marcusii, which has shown promise to be used as a feed additive. Therefore, this study investigated the use of P. marcusii as a possible source of pigmentation in layer hen feed to enhance egg yolk color. Paracoccus marcusii was fed to hens in a sucrose solution (10% m/v). The hens were fed daily and all eggs were collected for analysis. Dilutions of egg contents were plated onto selective media to detect the presence of known food pathogens (E. coli, Listeria, and Salmonella). In the feeding trial, there was no negative effect on hen body weight, egg production, or overall egg quality. There was a significant increase (P < 0.05) in yolk color as well as an increase in whole egg and yolk weight. There were also no known food pathogens detected in any of the egg samples. This study has shown promising results in using this bacterium as an effective feed additive for laying hens.

The Acidobacteria is one of the most abundant phyla in most soil types. Fynbos plants are endemic to South Africa, and these soils provide the ideal habitat for Acidobacteria, because of its low pH and oligotrophic properties. However, little is known about their distribution in the fynbos biome and the impact of cultivation of plants on Acidobacterial diversity. Therefore, the aim of this study was to determine the effect of seasonal changes and cultivation on the relative abundance and diversity of Acidobacteria associated with Aspalathus linearis (rooibos) and Cyclopia spp. (honeybush). This study was based on rhizosphere soil. A total of 32 and 31 operational taxonomic units (OTUs) were identified for honeybush and rooibos, respectively. The majority of these were classified as representatives of subdivisions 1, 2, 3, and 10. Significant differences in community compositions were observed between seasons for both honeybush and rooibos, as well as between the cultivated and uncultivated honeybush. Acidobacteria had a significantly positive correlation with pH, C, Ca2+, and P. In this study, we have shown the effect of seasonal changes, in summer and winter, and cultivation farming on the relative abundance and diversity of Acidobacteria present in the soil of rooibos and honeybush.

The Acidobacteriota is ubiquitous and is considered as one of the major bacterial phyla in soils. The current taxonomic classifications of this phylum are divided into 15 class-level subdivisions (SDs), with only 5 of these SDs containing cultured and fully described species. Within the fynbos biome, the Acidobacteriota has been reported as one of the dominant bacterial phyla, with relative abundances ranging between 4–26%. However, none of these studies reported on the specific distribution and diversity of the Acidobacteriota within these soils. Therefore, in this study we aimed to first determine the relative abundance and diversity of the Acidobacteriota in three pristine fynbos nature reserve soils, and secondly, whether differences in the acidobacterial composition can be attributed to environmental factors, such as soil abiotic properties. A total of 27 soil samples were collected at three nature reserves, namely Jonkershoek, Hottentots Holland, and Kogelberg. The variable V4-V5 region of the 16S rRNA gene was sequenced using the Ion Torrent S5 platform. The mean relative abundance of the Acidobacteriota were 9.02% for Jonkershoek, 14.91% for Kogelberg, and most significantly (p<0.05), 18.42% for Hottentots Holland. A total of 33 acidobacterial operational taxonomic units (OTUs) were identified. The dominant subdivisions identified in all samples included SDs 1, 2, and 3. Significant differences were observed in the distribution and composition of these OTUs between nature reserves. The SD1 were negatively correlated to soil pH, hydrogen (H+), potassium (K+) and carbon (C). In contrast, SD2, was positively correlated to soil pH, phosphorus (P), and K+, and unclassified members of SD3 was positively correlated to H+, K, and C. This study is the first to report on the specific acidobacterial distribution in pristine fynbos soils in South Africa.

The Cape Floristic Region (CFR) is globally known for its plant biodiversity, and its flora is commonly referred to as fynbos. At the same time, this area is under severe pressure from urbanization, agricultural expansion and the threat of invasive alien plants. Acacia, Eucalyptus and Pinus are the common invasive alien plants found across the biome and considerable time, effort and resources are put into the removal of invasive alien plants and the rehabilitation of native vegetation. Several studies have shown that invasion not only affects the composition of plant species, but also has a profound effect on the soil chemistry and microbial populations. Over the last few years, a number of studies have shown that the microbial populations of the CFR are unique to the area, and harbour many endemic species. The extent of the role they play in the invasion process is, however, still unclear. This review aims to provide an insight into the current knowledge on the different microbial populations from this system, and speculate what their role might be during invasion. More importantly, it places a spotlight on the lack of information about this process.

Aan die begin van die 21ste eeu het die toepassing van molekulêre tegnieke ‘n nuwe en opwindende wêreld vir wetenskaplikes oopgemaak. Hierdie tegnieke het gelei tot die ontdekking van groot hoeveelhede onbekende mikroörganismes regoor die wêreld wat aan die filum Acidobacteria behoort. Hierdie groep het in 1997 filumstatus ontvang met slegs drie gekweekte verteenwoordigers en vier hoofsubgroepe waarvan elke subgroep ooreenstem met ’n klas. Hierdie filum is vernoem na die eerste gekweekte verteenwoordiger, Acidobacterium capsulatum. Sedertdien het die aantal subgroepe toegeneem na 26 met ongeveer 60 gekweekte verteenwoordigers. Hierdie groep bakterieë kom algemeen in die grond voor, maar kan ook gevind word in varswatersediment, warmwaterbronne, suurmynmere en vele ander habitatte. Die Acidobacteria kom veral voor in grond met ‘n lae pH en lae voedingstoflading. Daarom is die fynbosbioom van Suid-Afrika die ideale habitat vir Acidobacteria.

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