Impact of egg disinfection of hatching eggs on the eggshell microbiome and bacterial load

Disinfection of hatching eggs is essential to ensure high quality production of broilers. Different protocols are followed in different hatcheries; however, only limited scientific evidence on how the disinfection procedures impact the microbiome is available. The aim of the present study was to characterize the microbiome and aerobic bacterial load of hatching eggs before disinfection and during the subsequent disinfection steps. The study included a group of visibly clean and a group of visibly dirty eggs. For dirty eggs, an initial wash in chlorine was performed, hereafter all eggs were submitted to two times fumigation and finally spray disinfection. The eggshell microbiome was characterized by sequencing of the total amount of 16S rRNA extracted from each sample, consisting of shell surface swabs of five eggs from the same group. In addition, the number of colony forming units (cfu) under aerobic conditions was established for each disinfection step. The disinfection procedure reduced the bacterial load from more than 104 cfu (initially visibly clean eggs) and 105 cfu (initially visibly dirty eggs) to less than 10 cfu per sample after disinfection for both groups of eggs. The microbiome of both initially visibly clean and initially visibly dirty eggs had the highest abundances of the phyla Firmicutes, Proteobacteria and Bacteroidetes. Within the phyla Firmicutes the relative abundances of Clostridiales decreased while Lactobacillus increased from before to after final disinfection. In conclusion, the investigated disinfection procedure is effective in reducing the bacterial load, and by adding a chlorine wash for initially visibly dirty eggs, the microbiome of initially visibly clean and initially visibly dirty eggs had a highly similar microflora after the final disinfection step.

Role of plant growth promoting rhizobacteria and Ag-nano particle in the bioremediation of heavy metals and maize growth under municipal wastewater irrigation

The investigation evaluated the role of plant growth promoting rhizobacteria (PGPR) and Ag-nano particle on the growth and metabolism of maize irrigated with municipal wastewater (MW). Three PGPR isolated from MW were identified on the basis of 16S-rRNA gene sequence analyses as Pseudomonas sp., Pseudomonas fluorescence, and Bacillus cereus. The municipal waste water was used to irrigate the maize seeds inoculated with 3 isolated PGPR. The isolated PGPR had catalase and oxidase enzymes, solubilize insoluble bound phosphate and exhibit antifungal and antibacterial activities. The colony forming unit (cfu) of the PGPR was inhibited by Ag-nano particle, but was stimulated by the municipal wastewater. The Ag-nano particles augmented the PGPR induced increase in root area and root length. The root-shoot ratio was also changed with the Ag-nano particles. The plants irrigated with municipal wastewater had higher activities of peroxidase and catalase which were further augmented by Ag-nano particle. The Ag- nano particle application modulated level of ABA (34%), IAA (55%), and GA (82%), increased proline production (70%) and encountered oxidative stress and augmented the bioremediation potential of PGPR for Pb, Cd, and Ni. Municipal wastewater needs to be treated with PGPR and Ag nano particle prior to be used for irrigation. This aims for the better growth of the plant and enhanced bioremediation of toxic heavy metals.

Evaluation of heterotrophic plate and chromogenic agar colony counting in water quality laboratories

The enumeration of bacteria using plate-based counts is a core technique used by food and water microbiology testing laboratories. However, manual counting of bacterial colonies is both time and labour intensive, can vary between operators and also requires manual entry of results into laboratory information management systems, which can be a source of data entry error. An alternative is to use automated digital colony counters, but there is a lack of peer-reviewed validation data to allow incorporation into standards. We compared the performance of digital counting technology (ProtoCOL3) against manual counting using criteria defined in internationally recognized standard methods. Digital colony counting provided a robust, standardized system suitable for adoption in a commercial testing environment. The digital technology has several advantages:•Improved measurement of uncertainty by using a standard and consistent counting methodology with less operator error.•Efficiency for labour and time (reduced cost).•Elimination of manual entry of data onto LIMS.•Faster result reporting to customers.

A comparison of two probiotic strains of bifidobacteria in premature infants

OBJECTIVE

To determine the impact of 2 probiotic bifidobacteria on the fecal microbiota of premature infants fed either human milk or formula.

STUDY DESIGN

In the first of two phase 1 clinical trials, 12 premature infants receiving formula feedings were assigned randomly to receive either Bifidobacterium longum ssp infantis or Bifidobacterium animalis ssp lactis in increasing doses during a 5-week period. In the second, 9 premature infants receiving their mother's milk received each of the two bifidobacteria for 2 weeks separated by a 1-week washout period. Serial stool specimens from each infant were analyzed by terminal restriction fragment-length polymorphism and quantitative polymerase chain reaction for bacterial composition.

RESULTS

Among the formula-fed infants, there was a greater increase in fecal bifidobacteria among infants receiving B infantis (Binf) than those receiving B lactis (Blac). This difference was most marked at a dose of 1.4 × 10(9) colony-forming units twice daily (P < .05). Bacterial diversity improved over dose/time in those infants receiving Binf. Among the human milk-fed infants, greater increases in fecal bifidobacteria and decreases in γ-Proteobacteria followed the administration of Binf than Blac. The B longum group (which includes Binf but not Blac) was the dominant bifidobacteria among the human milk-fed infants, regardless of the probiotic administered.

CONCLUSIONS

Binf was more effective at colonizing the fecal microbiota than Blac in both formula-fed and human milk-fed premature infants. The combination of human milk plus Binf resulted in the greatest fecal levels of bifidobacteria.

Identification and characterization of starvation induced msdgc-1 promoter involved in the c-di-GMP turnover

C-di-GMP [Bis-(3'-5')-cyclic-dimeric-guanosine monophosphate], a second messenger is involved in intracellular communication in the bacterial species. As a result several multi-cellular behaviors in both Gram-positive and Gram-negative bacteria are directly linked to the intracellular level of c-di-GMP. The cellular concentration of c-di-GMP is maintained by two opposing activities, diguanylate cyclase (DGC) and phosphodiesterase (PDE-A). In Mycobacterium smegmatis, a single bifunctional protein MSDGC-1 is responsible for the cellular concentration of c-di-GMP. A better understanding of the regulation of c-di-GMP at the genetic level is necessary to control the function of above two activities. In this work, we have characterized the promoter element present in msdgc-1 along with the +1 transcription start site and identified the sigma factors that regulate the transcription of msdgc-1. Interestingly, msdgc-1 utilizes SigA during the initial phase of growth, whereas near the stationary phase SigB containing RNA polymerase takes over the expression of msdgc-1. We report here that the promoter activity of msdgc-1 increases during starvation or depletion of carbon source like glucose or glycerol. When msdgc-1 is deleted, the numbers of viable cells are ~10 times higher in the stationary phase in comparison to that of the wild type. We propose here that msdgc-1 is involved in the regulation of cell population density.

Protein aggregation propensity is a crucial determinant of intracellular inclusion formation and quality control degradation

Protein aggregation is linked to many pathological conditions, including several neurodegenerative diseases. The aggregation propensities of proteins are thought to be controlled to a large extent by the physicochemical properties encoded in the primary sequence. We have previously exploited a set of amyloid β peptide (Aβ42) variants exhibiting a continuous gradient of intrinsic aggregation propensities to demonstrate that this rule applies in vivo in bacteria. In the present work we have characterized the behavior of these Aβ42 mutants when expressed in yeast. In contrast to bacteria, the intrinsic aggregation propensity is gated by yeast, in such a way that this property correlates with the formation of intracellular inclusions only above a specific aggregation threshold. Proteins displaying solubility levels above this threshold escape the inclusion formation pathway. In addition, the most aggregation-prone variants are selectively cleared by the yeast quality control degradation machinery. Thus, both inclusion formation and proteolysis target the same aggregation-prone variants and cooperate to minimize the presence of these potentially dangerous species in the cytosol. The demonstration that sorting to these pathways in eukaryotes is strongly influenced by protein primary sequence should facilitate the development of rational approaches to predict and hopefully prevent in vivo protein deposition.