This study aimed to characterize the role of Pseudomonas aeruginosa low-molecular-mass penicillin-binding proteins (LMM PBPs), namely, PBP4 (DacB), PBP5 (DacC), and PBP7 (PbpG), in peptidoglycan composition, ␤-lactam resistance, and ampC regulation. For this purpose, we constructed all single and multiple mutants of dacB, dacC, pbpG, and ampC from the wild-type P. aeruginosa PAO1 strain. Peptidoglycan composition was determined by high-performance liquid chromatography (HPLC), ampC expression by reverse transcription-PCR (RT-PCR), PBP patterns by a Bocillin FL-binding test, and antimicrobial susceptibility by MIC testing for a panel of ␤-lactams. Microscopy and growth rate analyses revealed no apparent major morphological changes for any of the mutants compared to the wild-type PAO1 strain. Of the single mutants, only dacC mutation led to significantly increased pentapeptide levels, showing that PBP5 is the major DD-carboxypeptidase in P. aeruginosa. Moreover, our results indicate that PBP4 and PBP7 play a significant role as DD-carboxypeptidase only if PBP5 is absent, and their DD-endopeptidase activity is also inferred. As expected, the inactivation of PBP4 led to a significant increase in ampC expression (around 50-fold), but, remarkably, the sequential inactivation of the three LMM PBPs produced a much greater increase (1,000-fold), which correlated with peptidoglycan pentapeptide levels. Finally, the ␤-lactam susceptibility profiles of the LMM PBP mutants correlated well with the ampC expression data. However, the inactivation of ampC in these mutants also evidenced a role of LMM PBPs, especially PBP5, in intrinsic ␤-lactam resistance. In summary, in addition to assessing the effect of P. aeruginosa LMM PBPs on peptidoglycan structure for the first time, we obtained results that represent a step forward in understanding the impact of these PBPs on ␤-lactam resistance, apparently driven by the interplay between their roles in AmpC induction, ␤-lactam trapping, and DD-carboxypeptidase/␤-lactamase activity. Pseudomonas aeruginosa is a frequent cause of nosocomial infections, especially affecting patients in intensive care units (ICUs) with mechanical ventilation-associated pneumonia or burn wound infections, both of which are associated with a high mortality rate (1). This pathogen is also the major cause of chronic respiratory infections in patients with cystic fibrosis and other underlying chronic respiratory diseases (2). One of the most striking features of P. aeruginosa is its extraordinary capacity for developing resistance to almost any available antibiotic by the selection of mutations in chromosomal genes (3). Among the mutationmediated ␤-lactam resistance mechanisms, particularly noteworthy are those leading to the constitutive overexpression of the inducible chromosomal cephalosporinase AmpC, which confers resistance to penicillins, cephalosporins, and monobactams (4). Additionally, mutations that lead to the repression or inactivation of the porin OprD, acting synergistically with inducible or cons...

New strategies must be developed to improve poultry performance and health. One of these strategies is the use of supplementations as sodium butyrate (SB) to improve the physiological status and then increasing the growth performance, but the best period of age in which the addition of SB is more effective on birds is not well understood. Therefore, the aim of this study was to investigate the effect of dietary inclusion of SB supplementation through the first, second or whole growth period on some physiological indices and growth performance of growing Japanese quail. In total, 240 unsexed 1-day-old quail chicks were divided into four groups (three replicates per group of 20 chicks in each). The first group was fed basal diet without SB from 1 to 42 days (control, T1), while SB at a rate of 1 g/kg basal diet was mixed with the feed of the 2nd, 3rdand 4thgroups of chicks from 1 to 21 days (SB 1 to 21, T2), 1 to 42 days (SB 1 to 42, T3) and 22 to 42 days (SB 22 to 42, T4) of age, respectively. The results stated that addition of SB significantly improved live BW at 21 days, feed conversion ratio (FCR) and BW gain (BWG) during 1 to 21 days in T2 and T3 groups compared to T1 and T4 groups. During the whole period, group T3 had higher BWG and better FCR than the other groups (T1, T2 and T4). At 21 days, no significant differences among all treatments were detected on haematology and serum biochemistry except total protein and cholesterol. At 42 days, SB supplementation significantly improved most serum constituents, haematological parameters, villus height and width of intestine and morphometry of immune organs. The group fed SB throughout the experiment (T3) showed the best results. In conclusion, it is recommended feeding quail on diets containing SB through the whole growth period to show its affirmative impact on the growth and physiological indices.

The twenty-two bacterial isolates were screened for cellulolytic activity using Congo red stain on Carboxymethylcellulose (CMC) agar plates inoculated with the isolates. All the isolates were found to hydrolyze Carboxymethylcellulose. Five bacterial isolates (FAY88, FAY103, FAY117. FAY136 and FAY182) were selected according to their higher production of carboxymethyl cellulase (CMCase). A Gram stain test was carried out to identify five isolates as Gram-positive rods, all associated mainly with members of the Bacillus. Their CMCase activities were 1.49, 1.26, 1.21, 1.21 and 1.24 U/ml, respectively. Genetic distances for the five selected strains with high cellulase activity based on the 79 bands obtained from the results of RAPD revealed the similarity according to the morphological characterization agrees with genetic distance. The SDS-PAGE analysis was revealed that, the molecular weight of crude cellulase isolated from Bacillus isolates was found approximately of 54 kDa.

Purpose This study aims to investigate profoundly the protection of oil painting from deterioration using molybdenum trisulphide quantum dots (MoS3 QDs) against microbe, dirt accumulation and ultraviolet (UV) degradation. Design/methodology/approach The protection of painting against different deterioration factors necessitates the sustainable methods and advanced techniques. Scanning electron microscopy and transmission electron microscopy have been used to investigate the morphological structure of the painting and MoS3 QDs, respectively, and optical microscopy was used to examine antibacterial activity of MoS3 QDs towards different types of bacteria. To investigate the protection of painting against deterioration, the Fourier transform IR spectroscopy (FTIR) was used to investigate the paintings left in open air for a year. Chemical composition and crystal structure of MoS3 QDs have been studied using X-ray diffraction and X-ray photoelectron spectroscopy analysis, respectively. Findings The addition of MoS3 nanoparticles into painted coatings enhances the durability of linseed oil-based paintings toward UV ageing regarding the change in colour which confirmed by FTIR analysis. The protection of oil painting opposed to various deterioration factors was developed by involving of MoS3 QDs in the coating of the painting. Antibacterial effect of MoS3 QDs was tested against different types of bacteria such as Pseudomonas aeruginosa confirming that the MoS3 QDs involved in the coatings of oil paintings produces a high protection layer for the paintings against several microbial attacks. In addition, coatings containing MoS3 QDs reduce the accumulation of dirt on oil paintings when subjected to open air for a year. Originality/value The novel MoS3 QDs was used to form a protective and transparent coating layer for the oil painting to overcome the deterioration, displays the promising protection and can be applied for different oil paintings.

Entomology Journal publishes original research papers and reviews from any entomological discipline or from directly allied fields in ecology, behavioral biology, Of eight termite species found in Egypt, the subterranean termite Psammotermes hypostoma Desneux is considered as the most important serious pest, which destroy the wooden structures in buildings and other wood products or any material containing cellulose. Therefore, cellulases enzymes are considered the main enzymes in the digestive system of termite. The termite digestive system is considered a target for best control.This report discusses the descriptive variations of alimentary canals for the worker and the soldier, also, the detection of three digestive enzymes; two of them belonging to cellulases enzymes (endo-β-1,4-glucanase, and cellobiase (β -glucosidase) and the third is amylase in guts extracts from the termite workers and soldiers. The workers had higher endo-β-1,4-glucanase and amylase activities, while soldiers had higher cellobiase (β-gl`ucosidase) activity. It is clear that the presence of α-amylase in the digestive system of P. hypostoma workers and soldiers means that this species of termite is able to decompose starch, which explains why termites attack grain silos.Effect of temperature and PH on enzyme activity showed that the optimum temperature /PH for workers were 70 °C/ PH6 for endoβ-1,4-glucanase, 50 °C/PH6 for cellobiase (β -glucosidase) and 70 °C/pH 7 for amylase, while, in case of soldiers, optimum temperature/pH were 70 °C/PH6 for endo-β-1,4-glucanase, 40 °C/PH6 for cellobiase (β-glucosidase) and 60 °C/PH 7 for amylase.This work is the first in Egypt concerning the study of the enzymes activities of the digestive system of termite and may be considered an initial step to contribute to control this species of termite by the development of new termiticides.

No abstract