Phylogeny of Three Palmwine Yeasts Genera

Sequences from three palm wine yeast genera namely Saccharomyces cerevisiae, Pichia kudriavzevii, and Candida ethanolica were analyzed to establish their phylogenetic relationships, geographical origin, and food matrix source of their close relatives. Up to 600 sequences present in yeasts representing close relatives of palm wine yeasts were examined. Pyhlogenetic trees constructed showed polyphyletic relationships in C. ethanolica whereas close relatives of S. cerevisiae and P. kudriavzevii showed little divergence. Sequence data for both Elaeis sp. and Raphia sp. palm trees showed that highest number of palm wine yeasts relatives sequence submissions to the Genbank were from China and beverages were mainly the sources of close relatives of S. cerevisiae and P. kudriavzevii whereas C. ethanolica closest relatives were from various non-food sources. Overall relatives of palm wine yeasts were not specific to any particular food or fermentation mix. The guanine-cytosine (G+C) content in P. kudriavzevii (57–58%) and C. ethanolica (56–57%) was higher than that of S. cerevisiae (47.3–51%). This suggests that the P. kudriavzevii and C. ethanolica have a higher recombination rate than S. cerevisiae strains analyzed. The data may help to understand palm wine yeast conservation and the diverse food matrixes and geographical origins where their close relatives exist

Molecular serotype and evolutionary lineage of Listeria monocytogenes isolated from different Nigerian food items

The molecular serotypes and the evolutionary lineage of Listeria monocytogenes isolated from various foods in Nigeria are yet to be documented. Consequently, popular uncooked food items known locally as Okazi Utazi, Onugbu, Ogbono, Garri and Egusi obtained from plants botanically known as Gnetum africanum, Gongronema latifolium, Vernonia amygdalina, Irvingia gabonensis, Manihot esculanta Crantz and Colocynthis Citrullus, respectively were analyzed. Molecular serotype of three chosen isolates was determined using multiplex polymerase chain reaction (PCR) serotyping before analysis based on prfA virulence gene cluster of L. monocytogenes was carried out to establish the evolutionary lineage. There was no L. monocytogenes detected in foods from I. gabonensis, M. esculanta Crantz and C. citrullus. However, the vegetables from G. africanum, G. latifolium and V. amygdalina showed the presence of the organism and chromogenic tests carried out on the three strains chosen from oxford formulation media indicated that they were not other non-pathogenic strains of Listeria. The V3 region of 16S rRNA gene of one strain showed that a close relative of the isolate is a strain implicated in an outbreak of listeriosis. Leafy vegetables could be a major vehicle for transmission of L. monocytogenes in Nigeria since this pathogenic bacterium occured in different vegetables analyzed.Key words: Listeria monocytogenes, serotype, lineage, pathogenic potential, Nigerian food

Data on evolutionary relationships of Aeromonas hydrophila and Serratia proteamaculans that attach to water tanks

Here the data on evolutionary relationships of persistent bacteria from water tanks and their close relatives are shown. Curated sequences of the hypervariable region of ribosomal ribonucleic acid (rRNA) obtained from a strain of Aeromonas hydrophila and two strains of Serratia proteamaculans after searches in the GenBank® database were analyzed. The analysis which included 104 other bacteria strains, was carried out using molecular evolutionary genetic analysis (MEGA 7.0) software

Optimization of ozone decomposition time and its effect on physicochemical and bacteriological quality of table water

Ozone is widely used in water disinfection and the concentration needed for the effective microbial elimination depends on the water source. In many bottled water producing industries, products containing ozone are quarantined after application to allow decomposition into diatomic oxygen molecules and oxygen atoms in order to eliminate any toxic effect. A process optimization was carried out to determine the ozone decomposition time in a table water producing factory in southern Nigeria. To this end, bottled water products injected with the ozone were collected from a bottling line immediately after production and monitored for ozone decomposition. Parameters like total dissolved solids, temperature and pH were determined and bacteriological analyses for total bacteria count and presence of Pseudomonas and coliforms were carried out. It was found that the ozone half-life was under 30 minutes and was no longer detectable after two and a half hours. For all analyzed stored products, the pH was in the range of 7.0-7.06, while the temperature was between 23 and 25 °C. The total dissolved solids ranged from 0.05 to 0.09 mg/mL, and there was no significant difference (p > 0.05) for the bottled products stored for 24 or 48 hours after the production. No bacteria were detected. The shorter quarantine period allows quicker distribution and highlights the importance of ozone decomposition testing for the process optimization, especially if equipment or water source change over time

The effect of growth conditions on the surface properties of Listeria monocytogenes

Due to the recent persistence of Listeria monocytogenes in food factory environments and an increase in outbreaks of Listeriosis, in particular some associated with duck meat products, an investigation was carried out to establish the potential effects of different growth conditions on the hydrophobicity of L. monocytogenes cells and to determine the behaviour of the cells in a minimal nutrient environment. It was found that duck meat extracts increased growth rate but did not alter the surface charge of the cells and when grown in minimal 010 and MCDB202 media the cells flocculated and showed more hydrophobicity than when grown in the rich media BHI. The modified surface of the organism behaved like an emulsifier and this led to the discovery for the first time, that there was formation of capsular exopolymeric substances (EPS) on the surface of planktonic cells of L. monocytogenes. After confirmation of the capsular EPS by two capsule stains, namely Nigrosin and Giemsa, the EPS was purified and proved to play a role in holding the cells together. It was also found to absorb water rapidly and can retain water for long periods suggesting that the EPS can contribute to the desiccation tolerance of L. monocytogenes cells embedded in a biofilm matrix. Chemical characterization of the EPS showed high levels of glycerol and phosphate indicating that the EPS is amphiphatic and may contain mainly glycerolphosphates

The effect of growth conditions on the surface properties of Listeria monocytogenes

Due to the recent persistence of Listeria monocytogenes in food factory environments and an increase in outbreaks of Listeriosis, in particular some associated with duck meat products, an investigation was carried out to establish the potential effects of different growth conditions on the hydrophobicity of L. monocytogenes cells and to determine the behaviour of the cells in a minimal nutrient environment. It was found that duck meat extracts increased growth rate but did not alter the surface charge of the cells and when grown in minimal 010 and MCDB202 media the cells flocculated and showed more hydrophobicity than when grown in the rich media BHI. The modified surface of the organism behaved like an emulsifier and this led to the discovery for the first time, that there was formation of capsular exopolymeric substances (EPS) on the surface of planktonic cells of L. monocytogenes. After confirmation of the capsular EPS by two capsule stains, namely Nigrosin and Giemsa, the EPS was purified and proved to play a role in holding the cells together. It was also found to absorb water rapidly and can retain water for long periods suggesting that the EPS can contribute to the desiccation tolerance of L. monocytogenes cells embedded in a biofilm matrix. Chemical characterization of the EPS showed high levels of glycerol and phosphate indicating that the EPS is amphiphatic and may contain mainly glycerolphosphates

Bacteriological Quality of Borehole and Sachet Water from a Community in Southeastern Nigeria

Water from boreholes and packaged commercial sachet water from different areas in a community in southern Nigeria was analyzed with membrane filtration for a snapshot of heterotrophic count and coliforms. Two boreholes out of the 20 analyzed had counts of over 500 Cfu/mL and 7 boreholes indicated the presence of coliforms. Sixteen samples out of 20 sachet water brands analyzed showed a regulatory product registration code, whereas 4 samples had no number or code indicating that they were not registered. The heterotrophic count of all sachet water was well within the limit for all samples analyzed, and coliform was detected in only two samples. The overall quality of borehole water in the community studied was rated D (65%), whereas the sachet water was rated C (90%) according to the World Health Organization (WHO) surveillance guidelines. Improvements in water quality structure in the community studied are required to help achieve WHO sustainable development goals on water sanitation. The etiology, virulence properties, epidemiology, and pathogenicity of bacteria associated with borehole and sachet water are also discussed

Improving food safety culture in Nigeria:A review of practical issues

As a developing nation and the most populous nation in Africa, Nigeria has enormous challenges connected with food safety culture. To produce and provide safe, secure and nutritious food, consumers and food businesses must abide by a set of shared values known as food safety culture. In Nigeria, food safety culture is a complex subject due to Nigeria’s heterogeneous and diverse nature, as demonstrated by its over 250 ethnic groups. As Nigeria becomes more urbanized and incomes continue to fluctuate at robust rates, few Nigerians are conscious of food safety issues. In addition, oversight from government regulators around food safety require improvement. Public engagement in food safety issues has not witnessed a promising trajectory in recent years. In this article, we provide a review of the food safety culture in Nigeria and its role and influence on various cases of food safety issues in Nigeria. Of interest to this paper are studies exploring consumer and food handler perceptions and behavior regarding food safety. In addition, keen attention is devoted to areas that are in need of additional research to help address practical and on-the-ground challenges associated with Nigeria’s food safety practices. This article suggests that improving food safety culture in Nigeria requires both applying the best management and communication approaches in different regions and understanding the local food safety practices