Fundamentals and Application Potential of Arsenic-Resistant Bacteria for Bioremediation in Rhizosphere: A Review

As a hazardous environmental metalloid toxicant, arsenic (As)—at elevated levels in water and soil—has created a major public health concern through its entry into the food chain by accumulation in crops. Among the various methods reported thus far for reclamation of As-contaminated crop fields, bioremediation using bacteria with plant-growth-promoting traits has been found to be a most promising solution. There is every possibility that bacterial isolates with the ability to remove or immobilize As could be used for successful bioremediation. However, bioremediation needs to define its boundaries between promise and field application, as most studies have been restricted to laboratory results only. Rhizosphere interactions play a critical role in monitoring As bioavailability to crop plants, thus a better understanding of it might improve rhizoremediation technologies. The challenges rely on the application of these novel approaches under field conditions. Despite some limitations, the prospect for successful stimulation and exploitation of microbial metabolism for As rhizoremediation appears to be very promising.     

Contrasting ability of deep and shallow rooting rice genotypes to grow through plough pans containing simulated biopores and cracks

Plant and Soil - Cracks and biopores in compacted soil such as plough pans could aid deep rooting, mitigating constraints to seasonal upland use of paddy fields for rice production. This research...     

Biological control of streptococcal infection in Nile tilapia Oreochromis niloticus (Linnaeus, 1758) using filter‐feeding bivalve mussel Pilsbryoconcha exilis (Lea, 1838)

Since bivalve mussels are able to graze heavily on bacteria, in this paper it is hypothesized that when mussels are cultured with fish, the filtering efficiency of the mussels will keep the bacterial population below a certain threshold and thus assist in reducing the risk of bacterial disease outbreaks. The ability of the filter‐feeding bivalve mussel Pilsbryoconcha exilis to control Streptococcus agalactiae was tested in a laboratory‐scale tilapia culture system. Juvenile Nile tilapia (Oreochromis niloticus), the bivalve mussel as well as the bacteria were cultured at different combinations using four treatments: treatment‐1: mussel and bacteria but no fish, treatment‐2: tilapia and mussel but no bacteria, treatment‐3: tilapia and bacteria but no mussel, and treatment‐4: tilapia, mussels, and bacteria. All treatments were run in three replicates; stocking rates were 10 tilapia juveniles; five mussels; and about 3.5 × 10⁵ colony forming units (CFU) ml^?1 of bacteria in 50‐L aquaria with 40‐L volume. The mussel reduced the bacterial population by 83.6–87.1% in a 3‐week period whereas in the absence of the mussel, the bacterial counts increased by 31.5%. Oresence of the mussel also resulted in significantly higher growth and lower mortality of tilapia juveniles than when the mussel was absent. The results of this experiment suggest that the freshwater mussel P. exilis could control the population of S. agalactiae in a laboratory‐scale tilapia culture system. Future studies should focus on the dynamic interactions among fish, mussels, and bacteria as well as on how input such as feed and other organic materials affect these interactions.     

Respiratory Viruses Associated Hospitalization among Children Aged <5 Years in Bangladesh: 2010-2014

Background

We combined hospital-based surveillance and health utilization survey data to estimate the incidence of respiratory viral infections associated hospitalization among children aged < 5 years in Bangladesh.

Methods

Surveillance physicians collected respiratory specimens from children aged <5 years hospitalized with respiratory illness and residing in the primary hospital catchment areas. We tested respiratory specimens for respiratory syncytial virus, parainfluenza viruses, human metapneumovirus, influenza, adenovirus and rhinoviruses using rRT-PCR. During 2013, we conducted a health utilization survey in the primary catchment areas of the hospitals to determine the proportion of all hospitalizations for respiratory illness among children aged <5 years at the surveillance hospitals during the preceding 12 months. We estimated the respiratory virus-specific incidence of hospitalization by dividing the estimated number of hospitalized children with a laboratory confirmed infection with a respiratory virus by the population aged <5 years of the catchment areas and adjusted for the proportion of children who were hospitalized at the surveillance hospitals.

Results

We estimated that the annual incidence per 1000 children (95% CI) of all cause associated respiratory hospitalization was 11.5 (10–12). The incidences per 1000 children (95% CI) per year for respiratory syncytial virus, parainfluenza, adenovirus, human metapneumovirus and influenza infections were 3(2–3), 0.5(0.4–0.8), 0.4 (0.3–0.6), 0.4 (0.3–0.6), and 0.4 (0.3–0.6) respectively. The incidences per 1000 children (95%CI) of rhinovirus-associated infections among hospitalized children were 5 (3–7), 2 (1–3), 1 (0.6–2), and 3 (2–4) in 2010, 2011, 2012 and 2013, respectively.

Conclusion

Our data suggest that respiratory viruses are associated with a substantial burden of hospitalization in children aged <5 years in Bangladesh.     

Novel effect of plant lectins on the inhibition of Streptococcus mutans biofilm formation on saliva-coated surface

Aims:  Dental caries is caused by the disturbance in oral homeostasis, marked by a notable increase in the population of Streptococcus mutans . Lectins are a group of plant proteins that are capable of recognizing the glycoconjugates present on the bacterial surface. The aim of this study was to evaluate the effect of seven plant lectins on the growth and initial adhesion of S. mutans .
Methods and Results:  Lectins of different carbohydrate specificities were isolated from plant sources by conventional methods of protein purification. The effect on growth of S. mutans was evaluated following CLSI guidelines. None of the lectins used in this study inhibited the bacterial growth and multiplication. The adherence and biofilm formation of bacteria to saliva-coated polystyrene plates was tested in the presence of plant lectins. All the plant lectins tested, inhibited both the adherence and biofilm in a concentration dependent manner. Confocal microscopy and scanning electron microscopy were employed to assess the biofilm formation in the presence of plant lectin (glucose/mannose-specific) at sub-minimal inhibitory concentrations. These evaluations revealed that lectins inhibited the clumping and attachment of S. mutans .
Conclusions:  Lectins tested here inhibited initial biofilm formation by S. mutans. Glucose/Mannose-specific lectin altered the adhesion arrangement of the bacteria on the saliva-coated surfaces.
Significance and Impact of the Study:  The plant lectins used in this study may offer a novel strategy to reduce development of dental caries by inhibiting the initial adhesion and subsequent biofilm formation of S. mutans.     

The impact of mass media family planning programmes on current use of contraception in urban Bangladesh

A sample of 871 currently married urban Bangladeshi women was used to assess the impact of mass media family planning programmes on current contraceptive use. The analyses suggested that radio had been playing a significant role in spreading family planning messages among eligible clients; 38% of women with access to a radio had heard of family planning messages while the figures for TV and newspaper were 18.5% and 8.5% respectively. Education, number of living children and current contraceptive use were important predictors of exposure to any mass media family planning messages. There was a negative relationship between breast-feeding and the current use of contraception indicating a low need for contraception among women who were breast-feeding.     

Evaluation of Porcine Intestinal Epitheliocytes as an In vitro Immunoassay System for the Selection of Probiotic Bifidobacteria to Alleviate Inflammatory Bowel Disease

Probiotics and Antimicrobial Proteins - The use of in vitro systems that allow efficient selection of probiotic candidates with immunomodulatory properties could significantly minimize the use of...     

Assessment of Zoonotic Transmission of Giardia and Cryptosporidium between Cattle and Humans in Rural Villages in Bangladesh

Giardia and Cryptosporidium are important causes of diarrhoea in Bangladesh. The high prevalence of both parasites in humans and cattle in rural Bangladesh and the common use of water ponds by village inhabitants and their animals suggest a potential for zoonotic transmission. Direct transmission of Giardia and Cryptosporidium between cattle and their handlers and indirect transmission through water ponds was investigated. Faecal/stool samples were collected from 623 calves and 125 calf handlers in a cross-sectional survey. In two villages, water samples were collected monthly from water ponds and faecal/stool samples were collected monthly from inhabitants and their cattle. Giardia cysts and Cryptosporidium oocysts were detected in water samples and in faecal/stool samples and positive samples were genotyped, to determine their human or animal origin. The prevalence of Giardia and Cryptosporidium in calves was 22% and 5% respectively. In calf handlers, the prevalence of Giardia and Cryptosporidium was 11.2% and 3.2% respectively. Both in the cross-sectional survey and in the longitudinal study in the villages, G. duodenalis assemblage E was most prevalent in calves, while in humans assemblage AII, BIII and BIV were found. In cattle, Cryptosporidium parvum, C. bovis and C. andersoni were identified, but no Cryptosporidium sequences were obtained from humans. Giardia and Cryptosporidium were detected in 14/24 and 12/24 water samples respectively. G. duodenalis assemblage E and BIV (-like), as well as C. andersoni and C. hominis were identified. Although the presence of Giardia and Cryptosporidium in both water ponds suggests that water-borne transmission of Giardia and Cryptosporidium is possible, the genotyping results indicate that there is no significant direct or indirect (water-borne) transmission of Giardia between cattle and people in this area of rural Bangladesh. No conclusions could be drawn for Cryptosporidium, because of the low number of sequences that were obtained from human and water samples.     

Molecular dynamics and combined docking studies for the identification of Zaire ebola virus inhibitors

Ebola virus (EBOV) is a lethal human pathogen with a risk of global spread of its zoonotic infections, and Ebolavirus Zaire specifically has the highest fatality rate amongst other species. There is a need for continuous effort towards having therapies, as a single licensed treatment to neutralize the EBOV is yet to come into reality. This present study virtually screened the MCULE database containing almost 36 million compounds against the structure of a Zaire Ebola viral protein (VP) 35 and a consensus scoring of both MCULE and CLCDDW docking programs remarked five compounds as potential hits. These compounds, with binding energies ranging from –7.9 to –8.9?kcal/mol, were assessed for predictions of their physicochemical and bioactivity properties, as well as absorption, distribution, metabolism, excretion, and toxicity (ADMET) criteria. The results of the 50?ns molecular dynamics simulations showed the presence of dynamic stability between ligand and protein complexes, and the structures remained significantly unchanged at the ligand-binding site throughout the simulation period. Both docking analysis and molecular dynamics simulation studies suggested strong binding affinity towards the receptor cavity and these selected compounds as potential inhibitors against the Zaire Ebola VP 35. With respect to inhibition constant values, bioavailability radar and other physicochemical properties, compound A (MCULE-1018045960-0-1) appeared to be the most promising hit compound. However, the ligand efficiency and ligand efficiency scale need improvement during optimization, and also validation via in vitro and in vivo studies are necessary to finally make a lead compound in treating Ebola virus diseases.

Communicated by Ramaswamy H. Sarma