Towards a risk-based food safety management system in the fresh produce supply chain in Da Nang, Viet Nam.

Food safety has emerged as a paramount concern for both Vietnamese consumers and the government. However, limited data are available on food safety management systems in Viet Nam. This study identified significant gaps in good agricultural and hygienic practices along the fresh produce chain (farmers and traditional wholesalers/market sellers) in the region of Da Nang, Viet Nam. This was achieved through a survey on good agricultural and hygienic practices for farmers (n = 100) and sellers (n = 100), which researchers further supplemented by microbiological analysis for E. coli, Salmonella spp., and Listeria monocytogenes on leafy greens, water in contact with produce and contact surfaces (hands). The results indicated that 86.0 % of farmers and 54.0 % of sellers received food safety training in the last 3 years; and women dominated both vegetable cultivation but also trading. Farm-level deficiencies included inadequate handwashing practices, lack of documentation for manure application schedules, improper washing and drying of harvest tools, failure to keep containers elevated off the ground, improper storage of vegetables, and inadequate covering of containers, with respectively 34.0 %, 30.3 %, 12.1 %, 41.7 % and 7.9 % of farmers executing the practice as prescribed by the WHO/FAO '5 keys of growing safer fruits and vegetables'. As for sellers, the most dominant gaps (<50.0 % compliance) were the way of handwashing and the practice of keeping containers elevated off the ground before, during, and after harvesting. The microbiological analysis confirmed that, in a total of 36 fresh produce samples including mustard greens, cucumber, lettuce, and crown daisy, the number of samples positive for E. coli, Salmonella spp., and L. monocytogenes were 12, 2, and 10 respectively. Samples of hands and the irrigation water showed high contamination with E. coli. Based on identified gaps, risk communication tools were developed and distributed amongst farmers, sellers, and Da Nang food safety management authority (governmental organisation performing inspections in the traditional food markets). As intervention, two farmers and two sellers were trained in safe agricultural practices for the cultivation of fresh vegetables (managerial intervention) and instructed to use tap water as irrigation water instead of uncontrolled surface water (technological intervention). A post-assessment was conducted, including redoing the survey on good practices and microbiological analysis. The outcome of these interventions showed positive results in terms of good agricultural and hygienic practices resulting in improved hygiene levels and safety of the fresh produce. The findings from this research have the potential to provide a model for the development of a science-based risk management strategy in alternative food chains or geographic areas in emerging countries.

Whole-genome analysis and secondary metabolites production of a new strain Brevibacillus halotolerans 7WMA2: A potential biocontrol agent against fungal pathogens.

The extensive usage of synthetic fungicides against fungal diseases has caused adverse impacts on both human and agricultural crops. Therefore, the current study aims to establish a new bacterium 7WMA2, as a biocontrol agent to achieve better antifungal results. The strain 7WMA2 was isolated from marine sediment, displayed a broad spectrum of several fungi that includes Alternaria alternata, Cladosporium sp., Candida albicans, Fusarium oxysporum, Trichosporon pullulans, and Trichophyton rubrum. The 16S rRNA phylogeny inferred that strain 7WMA2 was a member of Brevibacillus. The phylogenetic and biochemical analyses revealed that the strain 7WMA2 belongs to the species of Brevibacillus halotolerans. The complete genome sequence of Brevibacillus halotolerans 7WMA2 consists of a circular chromosome of 5,351,077 bp length with a GC content of 41.39 mol %, including 4433 CDS, 111 tRNA genes, and 36 rRNA genes. The genomic analysis showed 23 putative biosynthetic secondary metabolite gene clusters responsible for non-ribosomal peptides, polyketides and siderophores. The antifungal compounds concentrated from cell-free fermentation broth demonstrated strong inhibition of fungi, and the compounds are considerably thermal stable and adaptable to pH range 2-12. This complete genome sequence has provided insight for further exploration of antagonistic ability and its secondary metabolite compounds indicated feasibility as biological control agents against fungal infections.

Isolation of indole-3-acetic acid-producing Azospirillum brasilense from Vietnamese wet rice: Co-immobilization of isolate and microalgae as a sustainable biorefinery.

Production of indole-3-acetic acid (IAA) is well documented in various studies for the bacteria that inhabit the rhizosphere of plants, but with roots of wet rice, the outstandings have been not yet elucidated. This study began with the isolation of bacteria type strain Azospirillum sp. and developed the investigation to a screening of their ability in IAA production. This screening conducted a selection of only bacteria that was capable of the production of IAA with its content of over 25 µg. mL-1 for sequencing. Of 10 isolates only one resulted from the type strain Azospirillum brasilense (A. brasilense) with a similarity of 100%. Various factors that influence A. brasilense in biosynthesizing IAA such as temperature, pH, nitrogen presence and concentration of tryptophan in the culture medium were examined. The results indicated that the culture conditions were suitable for IAA biosynthesis at pH 6.5, 30 °C, culture media with nitrogen, and 0.1% trytophan. The next survey on the role of the immobilization of this bacteria with microalgae in alginate was highlighted to its support in microalgal growth. With the co-immobilization of bacteria and microalgae, the density of Chlorella vulgaris was significantly increased during 15-day culture, inducing 2.2 times of cell content in culture batch microalgae immobilized A. brasilense higher than that free-bacteria.