Banana crop produces large quantities of post-harvest biomass wastes that can be valorized as a renewable source of raw materials or bioenergy. However, their lignocellulosic nature and high water content prevent a broader use. They can be a potential source of natural biodegradable fibers, which can be used in papers and textile, and as reinforcement in the manufacture of several composite materials for aeronautics and cars. For this purpose, sustainable fiber extraction and isolation techniques need to be developed. In this study, we tested the conversion of soft peduncles tissues from three banana varieties to biogas and assessed the yield of recovery of the less digestible fibers. The process was found to be effective as a method for fiber extraction from banana peduncles. The amount and the quality of recovered fiber strongly depended both on the duration of anaerobic digestion and the banana variety. The tested cooking banana variety allowed the recovery of a significant amount of fibers while the soft tissues were converted to biomethane. The optimum digestion time for fibers and biogas recovery was identified as about 40 days, with yields of 0.2 ton_dry_fiber/ha/year and 349 m 3 _CH4/ha/year. These natural fibers have attractive technical, economic and environmental advantages. Dessert banana varieties were found to be more convenient for the biomethane production, as fiber degraded in less than 20 days of digestion time, and the total methane produced annually from banana peduncles ranged from 200 to 204 m 3 /ha/year. These results confirm that banana peduncles biomass can be considered as a source of renewable raw materials and energy in developing countries like Cameroon.

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Background Despite the global roll-out of rotavirus vaccines (RotaTeq/Rotarix / ROTAVAC/Rotasiil), mortality and morbidity due to group A rotavirus (RVA) remains high in sub-Saharan Africa, causing 104,000 deaths and 600,000 hospitalizations yearly. In Cameroon, Rotarix™ was introduced in March 2014, but, routine laboratory diagnosis of rotavirus infection is not yet a common practice, and vaccine effectiveness studies to determine the impact of vaccine introduction have not been done. Thus, studies examining RVA prevalence post vaccine introduction are needed. The study aim was to determine RVA prevalence in severe diarrhoea cases in Littoral region, Cameroon and investigate the role of other diarrheagenic pathogens in RVA-positive cases. Methods We carried out a study among hospitalized children < 5 years of age, presenting with acute gastroenteritis in selected hospitals of the Littoral region of Cameroon, from May 2015 to April 2016. Diarrheic stool samples and socio-demographic data including immunization and breastfeeding status were collected from these participating children. Samples were screened by ELISA (ProSpecT™ Rotavirus) for detection of RVA antigen and by gel-based RT-PCR for detection of the VP6 gene. Co-infection was assessed by multiplexed molecular detection of diarrheal pathogens using the Luminex xTAG GPP assay. Results The ELISA assay detected RVA antigen in 54.6% (71/130) of specimens, with 45, positive by VP6 RT-PCR and 54, positive using Luminex xTAG GPP. Luminex GPP was able to detect all 45 VP6 RT-PCR positive samples. Co-infections were found in 63.0% (34/54) of Luminex positive RVA infections, with Shigella (35.3%; 12/34) and ETEC (29.4%; 10/34) detected frequently. Of the 71 ELISA positive RVA cases, 57.8% (41/71) were fully vaccinated, receiving two doses of Rotarix. Conclusion This study provides insight on RVA prevalence in Cameroon, which could be useful for post-vaccine epidemiological studies, highlights higher than expected RVA prevalence in vaccinated children hospitalized for diarrhoea and provides the trend of RVA co-infection with other enteric pathogens. RVA genotyping is needed to determine circulating rotavirus genotypes in Cameroon, including those causing disease in vaccinated children.

The objective of this study was to devise a rapid mouse model for the in vivo screening of new anti Helicobacter pylori products. Six to eight week-old mice pretreated (7 days) with Amoxicillin/Metronidazole (25 mg/kg) to eliminate all Helicobacter-like organisms were inoculated (4x per week) with 200 µl of a bacterial culture (10 8 CFU/ml of H. pylori CCUG-39500). Colonisation of mouse stomach was assessed from day 1 to 15 post inoculation by the Gram stain, rapid urease test and antral mucus culture. These findings were used as a mouse model of Helicobacter pylori infection to assess the in vivo anti Helicobacter activities of two plant-derived molecules with proven cytoprotective, ulcer healing and in vitro anti Helicobacter properties (TN, a tabersonine chloride alkaloid from the fruits of Voacanga Africana and PAL, a protoberberine alkaloid ((7,8-dihydro-8-hydroxy-palmatine) from the bark of Enantia chlorantha). For up to 6 days post inoculation, the test organisms were recoverable by culture from 87.5% of the antral mucus samples while 100% of Gram stains were positive. The infection tended to clear naturally from day 9. Fifteen days post infection, only Gram stains were still positive (37.5%). Three-day oral administration of TN, PAL (50 mg/kg) and Metronidazole (25 mg/kg) completely eliminated the bacterial strain from the gastric antral mucus compared with the controls. This 4-week model is proposed as a rapid screening tool for in vivo evaluation of new anti H. pylori products in order to select candidates for detailed investigations.

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