Several actinomycetes isolated from nature were able to use both natural rubber (NR) and syntheticcis-1,4-polyisoprene rubber (IR) as a sole source of carbon. According to their degradation behavior, they were divided into two groups. Representatives of the first group grew only in direct contact to the rubber substrate and led to considerable disintegration of the material during cultivation. The second group consisted of weaker rubber decomposers that did not grow adhesively, as indicated by the formation of clear zones (translucent halos) around bacterial colonies after cultivation on NR dispersed in mineral agar. Taxonomic analysis of four selected strains based on 16S rRNA similarity examinations revealed twoGordoniasp. strains, VH2 and Kb2, and oneMycobacterium fortuitumstrain, NF4, belonging to the first group as well as oneMicromonospora aurantiacastrain, W2b, belonging to the second group. Schiff's reagent staining tests performed for each of the strains indicated colonization of the rubber surface, formation of a bacterial biofilm, and occurrence of compounds containing aldehyde groups during cultivation with NR latex gloves. Detailed analysis by means of scanning electron microscopy yielded further evidence for the two different microbial strategies and clarified the colonization efficiency. Thereby, strains VH2, Kb2, and NF4 directly adhered to and merged into the rubber material, while strain W2b produced mycelial corridors, especially on the surface of IR. Fourier transform infrared spectroscopy comprising the attenuated total reflectance technique was applied on NR latex gloves overgrown by cells of theGordoniastrains, which were the strongest rubber decomposers. Spectra demonstrated the decrease in number ofcis-1,4 double bonds, the formation of carbonyl groups, and the change of the overall chemical environment, indicating that an oxidative attack at the double bond is the first metabolic step of the biodegradation process.

The effect of pretreatment of several cis-1,4-polyisoprene containing rubbers on their biodegradability was examined. Tests were carried out with six

Background. Lack of knowledge about appropriate handwashing practices has caused great concerns for human health, especially in the risk of many communicable diseases. The objective of the current study is to determine the level of handwashing knowledge, attitudes, and practices among school students in Eastern Province Schools, Saudi Arabia. A cross-sectional survey was recruited from November 2019 to March 2020 to assess the level of the students’ handwashing knowledge. A reliable questionnaire was prepared (Cronbach’s alpha = 0.608) and conducted using a two-stage sampling technique. A total of 271 students participated in the study from primary, middle, and high schools; 80% were boys, most of whom displayed an acceptable level of knowledge on hand hygiene. Nearly 75% and 74% of boys and girls, respectively, gained knowledge about hand hygiene practices from their parents. Only 46% of the students thought that handwashing is a potential protective measure against diseases, whereas 34% thought it only removes dirt. Prevalence of handwashing with soap after using the toilet was recognized among 52% of the students. Additionally, 93% of the students used water and soap to wash their hands ( value < 0.001) and 97% suggested that soap and water are the best methods to wash their hands ( value < 0.001). There was a positive correlation between the mother’s education and hand hygiene practices ( value = 0.044). Results collectively indicated that handwashing knowledge and practices among school students in the Eastern Province are acceptable interventions in preventing the transmission of infectious diseases such as COVID-19. Indeed, further improvement conducted through specific health education programs to emphasize the role of handwashing in health hygiene is highly recommended.

Among several bacterial species belonging to the general Gordonia , Mycobacterium , Micromonospora , Pseudomonas , and Rhodococcus , only two mycobacterial isolates, Mycobacterium fortuitum strain NF4 and the new isolate Mycobacterium ratisbonense strain SD4, which was isolated from a sewage treatment plant, were capable of utilizing the multiply branched hydrocarbon squalane (2,6,10,15,19,23-hexamethyltetracosane) and its analogous unsaturated hydrocarbon squalene as the sole carbon source for growth. Detailed degradation studies and high-pressure liquid chromatography analysis showed a clear decrease of the concentrations of squalane and squalene during biomass increase. These results were supported by resting-cell experiments using strain SD4 and squalane or squalene as the substrate. The degradation of acyclic isoprenoids and alkanes as well as of acids derived from these compounds was also investigated. Inhibition of squalane and squalene degradation by acrylic acid indicated the possible involvement of β-oxidation in the degradation route. To our knowledge, this is the first report demonstrating the biodegradation of squalane by using defined axenic cultures.

Twenty‐six different bacterial strains were isolated from samples taken from different locations Dammam, Saudi Arabia, for screening of their polyhydroxyalkanoate (PHA) production capability. The initial screening was conducted by staining with Sudan Black B and Nile Red, followed by examination under fluorescence and electron microscopes to characterize PHA granule formation. The PHA‐producing bacterial isolates were identified using 16S rRNA gene analyses; the most potent bacterial strain was identified as Pseudomonas sp. strain‐P(16). The PHA production capability of this strain in the presence of different low‐cost carbon sources, such as rice bran, dates, and soy molasses, was analyzed. PHA production in the presence of rice bran, dates, and soy molasses was 90.9%, 82.6%, and 91.6%, respectively.