The aim of the study was to investigate microbial succession in the mushroom supply chain from compost, casing to fruit body formation and mushroom growth to the point of harvested, packing and point of sale. The microbial population dynamics of compost, casing and mushrooms were determined using a plate count technique, denaturing gradient gel electrophoresis (DGGE) and sequencing of 16S and 18S rDNA. Plating revealed greater abundance of bacteria, fungi and yeasts in mushroom compost compared to casing and fresh mushroom samples. The viable count method also showed that bacteria and yeasts increased significantly after harvest and Page 2 of 38 during cold storage. Sequencing revealed a more diverse culturable bacterial population in casing and on the mushrooms than in the compost. Phylogenetic analysis revealed a general trend of grouping of species from the same sources. In contrast, a higher microbial diversity was recorded in compost when using the DGGE method, which reflects cultural and non-culturable microorganisms. For compost and casing bacteria studied using DGGE, several species formed separate lineages, demonstrating highly diverse communities in these samples. Fungi were shown to be less abundant and less diverse compared to bacteria and yeasts. The study provides baseline knowledge of microbial populations and -succession trends in mushroom production systems using viable and non-viable methods. The information provided in this study may be useful for microbial ecology studies and to identify and develop biocontrol systems for pathogen control during production or to enhance pinning stimulation by knowing when to apply Pseudomonas spp. to ensure increased yield. Finally an insight is provided into microbial survival during cold storage and marketing of mushrooms. Potential antagonistic populations known to prevent spoilage, quality deterioration and extend shelf life are listed in this paper.

The information on fungal diversity and succession in table grapes during preharvest growth stages is critical in the development of a more targeted control strategy, to improve postharvest quality of table grapes.

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Botrytis cinerea is monitored at different phenological stages of table grapes at different agro-climatic sites.  Botrytis cinerea is detected in all evaluated phenological stages using ddPCR on asymptomatic samples.  Full boom stage of table grapes showed the most prevalence of Botrytis cinerea in high rainfall site.  Early preharvest monitoring of B. cinerea can assist growers reduce postharvest decay.

Commercial producers of white button mushrooms utilise a casing material to cover the spawn run compost, which stimulates the mushrooms' reproductive stage. Certain bacteria in this casing are responsible for this stimulation, which is known as pinning. Bacterial species richness and diversity within peat and peat-based casing mixtures made from industrial waste materials (i.e. those containing coir, wattle bark, bagasse and filter cake) were examined using denaturing gradient gel electrophoresis (DGGE) at three phases of mushroom growth: (1) casing, (2) pinning and (3) harvesting. Results from the DGGE established that higher bacterial species richness occurred at pinning and harvesting than at casing. Increases in bacterial population density at pinning were greater in the peat-based mixtures, which contained industrial waste materials, than in peat alone. Peat mixtures containing these alternative materials are therefore favourable substrates for bacterial growth. The DGGE profiles for pasteurised casing materials reflected their ability to rapidly reestablish the original bacterial community. The bacteria found to be dominant in casing materials during pinning were closely related to Pseudomonas, Flavobacterium, alpha-Proteobacterium, beta-Proteobacterium, gamma-Proteobacterium, delta-Proteobacterium and uncultured species.

Highlights • A standard for air quality of postharvest fruit environments is proposed. • Dominant Penicillium air mycoflora in postharvest fruit environments were presented. • Pathogenic Penicillium spp. in the air of fruit handling environment were profiled. • Repack facilities had the highest air mycoflora counts than any other facility.