Rapid screening method for isolation of glycerol-consuming bacteria for ethanol production

Large numbers of glycerol-consuming bacteria are present in nature; hence bioconversion of glycerol into biofuel which is bioethanol is one of the interests. The effective screening procedure is needed to screen and isolate broad ranges of bacteria from environment. The screening method was modified based on enzymatic oxidation of ethanol, which is correlated to reduction of 2,6-dichlorophenol-indophenol dye that resulted in the formation of yellow zone. Approximately 300 colonies were able to grow on minimal media using glycerol as sole carbon. Only about 70 isolates showed positive result when using the modified ethanol production assay after pre-screening stage. The formation of decolourized zone was apparent using modified assay containing 5 mL/L of 0.05M 2,6-dichlorophenol-indophenol, 10 mL of reaction mixture and 500 μl/L of enzyme, respectively. The ethanol production capability of the isolates was further proven by anaerobic fermentation as a quantitative method. This modified method is applicable in screening for ethanol producer from glycerol as carbon source allows rapid and more bacteria can be screened

Glycerol as alternative substrate for bioethanol production using free and immobilized Escherichia coli SS1

Increase in the crude oil price and the concern about climatic change has resulted in the rapid increase of biodiesel production. In the production of this biofuel, glycerol will essentially generate as by-product. As a result, the production of glycerol has also increased. Biofuel from glycerol can be categorized as second generation of biofuels where it can be used to replace the first generation of biofuel including glucose and vegetable oils as feedstock to reduce the competition between biofuel and food production. Thus the aim of this study is to carry out bioethanol production using glycerol in batch and continuous fermentation by free and immobilized Escherichia coli SS1. Bioethanol production was carried out using both free and immobilized cells in 2 liter bioreactor with 800 mL working volume. Glycerol concentration of 20 g/L, 35 g/L and 45 g/L were used as initial substrate concentration in batch free cells fermentations. Dilution rate of 0.1/h and 0.2/h were used and was selected based on the maximum specific growth rate from batch fermentation. Immobilization of E.coli SS1 was done by using sodium alginate and calcium chloride as crossed link agent. Optimization study was done to determine the stability and rigidity of alginate beads. Parameters involved in this optimization study were sodium alginate concentration, calcium chloride concentration, beads diameter and initial pH of medium. The optimum conditions for cell immobilization were 0.2 M calcium chloride, at pH 7 with 3% concentration of sodium alginate and beads diameter of 3 mm. Results showed that high glycerol concentration did not affect the yield of ethanol with the yield was closed to theoretical yield; 1 mol ethanol per 1 mol glycerol. Dilution rate of 0.1/h was the optimum dilution rate to be used in this fermentation where glycerol consumption and ethanol production was similar to batch fermentation by yielding 1 mol ethanol per mol glycerol. Continuous fermentation of immobilized E. coli SS1 was done by using the optimized beads with the dilution rate of 0.2/h and 20 g/L. The results showed that immobilized cells can last up to 3rd cycle of continuous fermentation. Ethanol production obtained was 6.17 g/L by utilizing approximately 19 g/L glycerol. The yield achieved was 0.65 mol ethanol per mol glycerol. Compare with other studies, the result in this experiment was slightly lower where other managed to obtain about 0.6 to 0.8 mol ethanol per mol glycerol, respectively

The putative roles and functions of indel, repetition and duplication events in alphavirus non-structural protein 3 hypervariable domain (NSP3 HVD) in evolution, viability and re-emergence

Alphavirus non-structural proteins 1–4 (nsP1, nsP2, nsP3, and nsP4) are known to be crucial for alphavirus RNA replication and translation. To date, nsP3 has been demonstrated to mediate many virus–host protein–protein interactions in several fundamental alphavirus mechanisms, particularly during the early stages of replication. However, the molecular pathways and proteins networks underlying these mechanisms remain poorly described. This is due to the low genetic sequence homology of the nsP3 protein among the alphavirus species, especially at its 30 C-terminal domain, the hypervariable domain (HVD). Moreover, the nsP3 HVD is almost or completely intrinsically disordered and has a poor ability to form secondary structures. Evolution in the nsP3 HVD region allows the alphavirus to adapt to vertebrate and insect hosts. This review focuses on the putative roles and functions of indel, repetition, and duplication events that have occurred in the alphavirus nsP3 HVD, including characterization of the differences and their implications for specificity in the context of virus–host interactions in fundamental alphavirus mechanisms, which have thus directly facilitated the evolution, adaptation, viability, and re-emergence of these viruses

Risk factors and clinical outcome of profound thrombocytopenia in adult patients with DENV infections

Severe thrombocytopenia is common in dengue virus (DENV) infections. However, studies focusing on the role of profound thrombocytopenia (PT) (nadir platelet counts ≤ 20 000/mm3) in DENV infections are scarce. This study aims to identify the associated features and outcome of DENV patients with PT. It involves 237 adult hospitalized patients who were DENV PCR positive. The presence of comorbidity (AOR = 4.625; 95% CI = 1.113–19.230), higher admission hematocrit (AOR = 1.213; 95% CI = 1.067–1.379), lower admission albumin (AOR = 0.870; 95% CI = 0.766–0.988) and lower admission platelets (AOR = 0.980; 95% CI = 0.969–0.991) was associated with platelets ≤ 20 000/mm3 in multivariate logistic regression. PT was not affected by DENV serotypes, coinfections and secondary DENV infections. Patients with PT had significantly higher risk of experiencing warning signs (AOR = 3.709, 95% CI = 1.089–12.634) and longer hospital stay (AOR = 1.943, 95% CI = 1.010–3.774). However, severe dengue disease, hemorrhagic manifestations and need for intensive care were not significantly associated with PT

The Putative Roles and Functions of Indel, Repetition and Duplication Events in Alphavirus Non-Structural Protein 3 Hypervariable Domain (nsP3 HVD) in Evolution, Viability and Re-Emergence

Alphavirus non-structural proteins 1–4 (nsP1, nsP2, nsP3, and nsP4) are known to be crucial for alphavirus RNA replication and translation. To date, nsP3 has been demonstrated to mediate many virus–host protein–protein interactions in several fundamental alphavirus mechanisms, particularly during the early stages of replication. However, the molecular pathways and proteins networks underlying these mechanisms remain poorly described. This is due to the low genetic sequence homology of the nsP3 protein among the alphavirus species, especially at its 3′ C-terminal domain, the hypervariable domain (HVD). Moreover, the nsP3 HVD is almost or completely intrinsically disordered and has a poor ability to form secondary structures. Evolution in the nsP3 HVD region allows the alphavirus to adapt to vertebrate and insect hosts. This review focuses on the putative roles and functions of indel, repetition, and duplication events that have occurred in the alphavirus nsP3 HVD, including characterization of the differences and their implications for specificity in the context of virus–host interactions in fundamental alphavirus mechanisms, which have thus directly facilitated the evolution, adaptation, viability, and re-emergence of these viruses

Impact of dengue virus (DENV) co-infection on clinical manifestations, disease severity and laboratory parameters

BACKGROUND: The co-circulation of 4 DENV serotypes in geographically expanding area, has resulted in increasing occurrence of DENV co-infections. However, studies assessing the clinical impact of DENV co-infections have been scarce and have involved small number of patients. This study explores the impact of DENV co-infection on clinical manifestations and laboratory parameters. METHODS: This retrospective study involved consecutive hospitalized patients with non-structural protein 1 (NS1) antigen positivity during an outbreak (Jan to April 2014). Multiplex RT-PCR was performed directly on NS1 positive serum samples to detect and determine the DENV serotypes. All PCR-positive serum samples were inoculated onto C6/36 cells. Multiplex PCR was repeated on the supernatant of the first blind passage of the serum-infected cells. Random samples of supernatant from the first passage of C6/36 infected cells were subjected to whole genome sequencing. Clinical and laboratory variables were compared between patients with and without DENV co-infections. RESULTS: Of the 290 NS1 positive serum samples, 280 were PCR positive for DENV. Medical notes of 262 patients were available for analysis. All 4 DENV serotypes were identified. Of the 262 patients, forty patients (15.3 %) had DENV co-infections: DENV-1/DENV-2(85 %), DENV-1/DENV-3 (12.5 %) and DENV-2/DENV-3 (2.5 %). Another 222 patients (84.7 %) were infected with single DENV serotype (mono-infection), with DENV- 1 (76.6 %) and DENV- 2 (19.8 %) predominating. Secondary dengue infections occurred in 31.3 % patients. Whole genome sequences of random samples representing DENV-1 and DENV-2 showed heterogeneity amongst the DENVs. Multivariate analysis revealed that pleural effusion and the presence of warning signs were significantly higher in the co-infected group, both in the overall and subgroup analysis. Diarrhoea was negatively associated with co-infection. Additionally, DENV-2 co-infected patients had higher frequency of patients with severe thrombocytopenia (platelet count < 50,000/mm(3)), whereas DENV-2 mono-infections presented more commonly with myalgia. Elevated creatinine levels were more frequent amongst the co-infected patients in univariate analysis. Haemoconcentration and haemorrhagic manifestations were not higher amongst the co-infected patients. Serotypes associated with severe dengue were: DENV-1 (n = 9), DENV-2 (n = 1), DENV-3 (n = 1) in mono-infected patients and DENV-1/DENV-2 (n = 5) and DENV-1/DENV-3 (n = 1) amongst the co-infected patients. CONCLUSION: DENV co-infections are not uncommon in a hyperendemic region and co-infected patients are skewed towards more severe clinical manifestations compared to mono-infected patients