Evaluation of a novel thermo-alkaline Staphylococcus aureus lipase for application in detergent formulations

AbstractAn extracellular lipase of a newly isolated S. aureus strain ALA1 (SAL4) was purified from the optimized culture medium. The SAL4 specific activity determined at 60°C and pH 12 by using olive oil emulsion or TC4, reached 7215U/mg and 2484U/mg, respectively. The 38 NH2-terminal amino acid sequence of the purified enzyme starting with two extra amino acid residues (LK) was similar to known staphylococcal lipase sequences. This novel lipase maintained almost 100% and 75% of its full activity in a pH range of 4.0–12 after a 24h incubation or after 0.5h treatment at 70°C, respectively. Interestingly, SAL4 displayed appreciable stability toward oxidizing agents, anionic and non-ionic surfactants in addition to its compatibility with several commercial detergents. Overall, these interesting characteristics make this new lipase promising for its application in detergent industry

Genetic Background of Antimicrobial Resistance in Multiantimicrobial-Resistant Escherichia Coli Isolates From Feces Of Healthy Broiler Chickens In Tunisia

Multiantimicrobial-resistant Escherichia coli isolates are a global human health problem causing increasing morbidity and mortality. Genes encoding antimicrobial resistance are mainly harbored on mobile genetic elements (MGEs) such as transposons and plasmids as well as integrons, which enhance their rapid spread. The aim of this study was to characterize 83 multiantimicrobial-resistant E. coli isolates recovered from healthy broiler chickens. Among 78 tetracycline-resistant isolates, the tetA, tetB, and tetC genes were detected in 59 (75.6%), 14 (17.9%), and one (1.2%) isolates, respectively. The sul1, sul2, and sul3 genes were detected 31 (46.2%), 16 (23.8%), and 6 (8.9%) isolates, respectively, among 67 sulfonamide-resistant isolates. The PCR-based replicon typing method showed plasmids in 29 isolates, IncFIB (19), IncI1-Iγ (17), IncF (14), IncK (14), IncFIC (10), IncP (8), IncY (3), IncHI2 (1), and IncX (1). The class 1 and 2 integrons were detected in 57 and 2 isolates, respectively; one isolate harbored both integrons. Seven and one gene cassette arrays were identified in class 1 and class 2 integrons, respectively. Our findings show that multiantimicrobial-resistant E. coli isolates from chickens serve as reservoirs of highly diverse and abundant tet and sul genes and plasmid replicons. Such isolates and MGEs pose a potential health threat to the public and animal farming

Comparison of Nanopore and Synthesis-Based Next-Generation Sequencing Platforms for SARS-CoV-2 Variant Monitoring in Wastewater

Shortly after the beginning of the SARS-CoV-2 pandemic, many countries implemented sewage sentinel systems to monitor the circulation of the virus in the population. A fundamental part of these surveillance programs is the variant tracking through sequencing approaches to monitor and identify new variants or mutations that may be of importance. Two of the main sequencing platforms are Illumina and Oxford Nanopore Technologies. Here, we compare the performance of MiSeq (Illumina) and MinION (Oxford Nanopore Technologies), as well as two different data processing pipelines, to determine the effect they may have on the results. MiSeq showed higher sequencing coverage, lower error rate, and better capacity to detect and accurately estimate variant abundances than MinION R9.4.1 flow cell data. The use of different variant callers (LoFreq and iVar) and approaches to calculate the variant proportions had a remarkable impact on the results generated from wastewater samples. Freyja, coupled with iVar, may be more sensitive and accurate than LoFreq, especially with MinION data, but it comes at the cost of having a higher error rate. The analysis of MinION R10.4.1 flow cell data using Freyja combined with iVar narrows the gap with MiSeq performance in terms of read quality, accuracy, sensitivity, and number of detected mutations. Although MiSeq should still be considered as the standard method for SARS-CoV-2 variant tracking, MinION’s versatility and rapid turnaround time may represent a clear advantage during the ongoing pandemic

Evaluation of a novel thermo-alkaline Staphylococcus aureus lipase for application in detergent formulations

An extracellular lipase of a newly isolated S. aureus strain ALA1 (SAL4) was purified from the optimized culture medium. The SAL4 specific activity determined at 60 °C and pH 12 by using olive oil emulsion or TC4, reached 7215 U/mg and 2484 U/mg, respectively. The 38 NH2-terminal amino acid sequence of the purified enzyme starting with two extra amino acid residues (LK) was similar to known staphylococcal lipase sequences. This novel lipase maintained almost 100% and 75% of its full activity in a pH range of 4.0–12 after a 24 h incubation or after 0.5 h treatment at 70 °C, respectively. Interestingly, SAL4 displayed appreciable stability toward oxidizing agents, anionic and non-ionic surfactants in addition to its compatibility with several commercial detergents. Overall, these interesting characteristics make this new lipase promising for its application in detergent industry. Keywords: Staphylococcus aureus lipase, Purification, Characterization, Thermo-alkaline, Detergent-stabl

Removal of Astrovirus from Water and Sewage Treatment Plants, Evaluated by a Competitive Reverse Transcription-PCR

Quantification of human astrovirus genogroups A and B was undertaken with sewage and water samples, collected from the Greater Cairo area in Egypt from November 1998 to October 1999, by a competitive reverse transcription (RT)-PCR with an internal control. The number of RNA copies of genogroup A/liter in quantifiable samples ranged from 3.4 × 10(3) to 5.6 × 10(6) in raw sewage and from 3.4 × 10(3) to 1.1 × 10(4) in treated effluents, while the number of infectious units per liter in these samples as determined by cell culture RT-PCR (CC-RT-PCR U/liter) ranged from 3.3 × 10(1) to 3.3 × 10(3) in raw sewage and was 3.3 × 10(0) in treated effluents. On the other hand, the number of RNA copies/liter in quantifiable genogroup B samples ranged from 1.1 × 10(4) to 8.7 × 10(6) in raw sewage and from 1.1 × 10(3) to 6.2 × 10(5) in treated effluents, while the number of infectious units ranged from 3.3 × 10(1) to 3.3 × 10(5) CC-RT-PCR U/liter in raw sewage and from 3.3 × 10(1) to 3.3 × 10(2) CC-RT-PCR U/liter in treated effluents. These higher numbers of both RNA copies/liter and infectious particles of genogroup B may indicate the emergence of genogroup B in the area. Additionally, genogroup B astrovirus exhibited a higher resistance to removal treatments with regard to the number of RNA copies per ml. When the equipment for real-time approaches is unavailable, a competitive PCR or RT-PCR with an internal control may be employed for virus quantification in validations of the efficiency of virus removal treatments

Prevalence of cattle ticks in various agro-ecological zones of Khyber Pakhtunkhwa, and evaluation of botanical extracts against Hyalomma detritum

Background: The occurrence of infestation by ticks on livestock is a significant challenge in several semi-tropical and tropical countries including Pakistan. Polluted environment and adapted tolerance by ticks against acaricide are the limiting factors that restrict the management of ticks globally. Methods: In this study, we evaluated the infestation by ticks on cattle from numerous livestock farms present in different districts and agroecological areas of Khyber Pakhtunkhwa, a province in Pakistan. Furthermore, we compared the anti-tick efficacy of different botanicals using ethanolic and aqueous extracts to control Hyalomma detritum. Results: The prevalence rate was 1.78, 35.37, 36.23, 8.15, 15.50, 0.29 and 2.67 percent for Amblyoma varigatum (A. varigatum), Hyalomma anatolicum (H. anatolicum), H. detritum, Hylomma rufipes (H. rufipes), Hyalomma truncatem (H. truncatum), Rhipicephalus microplus (R. microplus), and Hyalomma kashmirensis (H. kashmirensis), respectively. In terms of high mortality rate of ticks, extracts derived from Calotropis procera flower (93.33%), Citrullus colocynthis fruit (95.0%) and Calotropis procera flower (89.4%) showed significantly high efficancy (P < 0.05) than the extracts derived from other plants. In terms of their efficacy in causing mortality of H. detritum tick, Calotropis procera flower, Citrullus colocynthis fruit and Calotropis procera leaves extracts displayed non-significant variation. Conclusion: This work revealed that the cattle tick H. detritum can be successfully controlled by employing both ethanolic and aqueous plant extracts. The intensive use of insecticides and chemical drugs are costly and may affect human health negatively due to residual effects in milk and animal meat

Machine milking parameters for an efficient and healthy milking in dairy camels (Camelus dromedarius)

International audienceThe effect of vacuum level and pulsation rate on machine milking efficiency in lactating dromedary camels were studied in 2 separate experiments. In the first experiment, a total of 14 multiparous camels in early (n=7) and late (n=7) lactation were used to study the effects of vacuum level (45 and 50 kPa) and pulsation rate (52 and 60 pulsations/min) on milk fractionation and flows traits. At the morning milking, volumes of machine milk (MM), machine stripping milk (MSM) and residual milk (RM) were recorded at two different days. For the second experiment, another 10 multiparous dromedary camels at mid stage of lactation were used to evaluate teat condition and udder health during 10 weeks. Milk samples were collected weekly at each milking and analysed for major milk constitutes and udder health. The 50 kPa vacuum level and 60 pulsations/min decreased (P<0.05) the MSM (from 15.2 to 5.9%) and RM (from 44.1 to 29.8%) compared to 45 kPa and 52 pulsation rate. Moreover, milking camels at high vacuum level resulted in significantly more milk in a shorter time with higher milk flows rate at early stage of lactation. No subclinical mastitis was detected in any of udders quarters as indicated by the CMT (<1), SCC (387x10(3)+/- 86 cells/ mL) and bacteriology (coliform=0 and total flora=32097 +/- 396 ufc/mL) test. There were no differences in teat diameters, texture and color before and after milking. In conclusion, dromedary camels are readily to milk efficiently at 50 kPa and 60 pulsations/min without affecting negatively teat condition or udder health

Effects of different host plants on population fitness of pea aphid (Acyrthosiphon pisum)

Background: Host plants not only provide and living places and energy materials for insects, but also influence insect population parameters and population fitness. Methods: This study examined the influence of various host plant species on the fitness of pea aphid (Acyrthosiphon pisum). The biological parameters and population parameters of pea aphid on 6 different host plants (Vicia fabae, Pisum sativum, Medicago sativa, Trifolium pratense, Onobrychis viciaefolia and Melilotus officinalis) were observed and counted by ecological experiments, which were carried out in a control chamber. Results: The results showed that the developmental duration of 1st and 2nd instar nymphs of pea aphids on T. pratense and P. sativum was significantly prolonged, whereas that of 3rd and 4th instar nymphs on O. viciaefolia and M. officinalis was significantly shortened. Compared with the pea aphid on the V. faba, the longevity of adults on M. officinalis and P. sativum was significantly prolonged, but only the generation time on P. sativum was significantly prolonged. Moreover, the survival rate of nymphs was significantly lower on O. viciaefolia and M. sativa than on others. Net reproductive rate and mean generation time on V. faba were significantly higher than in other host plants. The intrinsic rate of increase (rm) and finite rate of increase (λ) of pea aphid feeding of A. pisum on P. sativum and O. viciaefolia decreased. However, those on the double population time on P. sativum and O. viciaefolia were significantly higher than the others. Conclusion: The findings will clarify the population fitness of pea aphids on different hosts and guide the rational distribution of different host plants, and provide new references for aphid control strategies

<span style="color:rgb( 34 , 34 , 34 )">Dynamic and Seasonal Distribution of Enteric Viruses in Surface and Well Water in Riyadh (Saudi Arabia).</span>

Enteric viruses are the major cause of gastroenteritis and enteric hepatitis worldwide, but in some areas like Saudi Arabia, little is known about their presence in water sources. The available information from clinical samples is not enough to figure out their actual prevalence. The aim of this study was to gather information for the first time in Saudi Arabia on the presence of the Norovirus (NoV) genogroup GI and GII, hepatitis A virus (HAV), and hepatitis E virus (HEV) in water. For this purpose, thirteen monthly samples were collected from Lake Wadi Hanifa and surrounding wells from December 2014 to November 2015. Viruses were detected and quantified using real-time RT-qPCR. Despite HEV findings being anecdotic, our results highlight interesting behaviors of the other viruses. There was a higher prevalence of noroviruses in Wadi Hanifa samples than in well water samples (46.43% vs. 12.5% of NoV GI; 66.67% vs. 8.33% of NoV GII). On the contrary, similar levels of HAV positivity were observed (40.48% in surface water vs. 43.06% in well water). Also, a strong influence of flooding events on HAV and NoV GI occurrence was observed in both surface and well water samples, with NoV GII apparently not affected