Bench-Scale Preparation of Mushroom Substrates In Controlled Environments

Abstract

Conventional composting for mushroom cultivation involves a largely uncontrolled phase in which there are wide variations in temperature and oxygen level, resulting in the production of odor pollutants. The experiments reported in this paper investigated environmental conditions for compost preparation in an attempt to minimize odor production. Substrates for mushroom culture were prepared in flasks under controlled temperature and aeration. The temperature (48 to 72°C), 0 2 concentration (0.6 to 8.7 percent v /v) and duration (6 or 20 h) of an initial pasteurization phase were varied before all the substrates were given a standard aerated conditioning period at 47°C Compost decomposition, initial mineralization rates of 14 C labelled glutamic acid (a measure of microbial activity) and actinomycete and fungal populations all decreased as the pasteurization temperature increased from 48°C to 72°C The duration and 0 2 concentration of the pasteurization treatment did not affect the overall decomposition of the substrate, mineralization of 14 C labelled glutamic acid and subsequent mushroom mycelial extension rate and yield from the substrate. Under the controlled temperature conditions, the optimum pasteurization temperature for mushroom mycelial extension rate and sporophore yield was 60°C but possible benefits of higher temperature zones in a large stack situation were identified: 1) a higher concentration of ammonia which may assist substrate degradation over a prolonged period; 2) the development of high populations of intercellular bacteria following pasteurization at 72°C, 0.6 percent 02; 3) the recovery of low rates of mineralization of 14 C labelled glutamic acid following the pasteurization of substrate at 72°C to rates above those of the 48°C and 60°C pasteurization treatments.

Monitoring of Changes in Substrate Characteristics during Mushroom Compost Production

“…Chemical data gave a direct indication of the efficiency of conversion. Reduction in DM between raw material mixing and end of phase I was caused by microorganisms breaking down the substrate (17). Increasing ash content and EC levels, along with a fall in TSC and TSP, indicated that microbial bioconversion had occurred.…”

Olfactory Response to Mushroom Composting Emissions as a Function of Chemical Concentration

“…Composts incubated anaerobically in enclosed flasks (Noble et al, 1997) produced more DMS than H 2 S at moisture contents below 73%, but proportionately more H 2 S in wetter composts (unpublished data, 1997). No effect of compost moisture content on the proportion of DMS and H 2 S emissions was found here; this may be due to variation in moisture content within large stacks.…”

Eradication of Plasmodiophora brassicae during composting of wastes

“…Galls (3-5 g) from young plants were enclosed within fine mesh polyester sample bags and placed in the centre of the compost feedstocks in 2-L Quickfit multiadapter flasks (Fischer Scientific) and immersed in thermostatically controlled water baths or chambers (Noble et al ., 1997). Where required, the flasks were aerated for 2 min in every 30 min at a flow rate of 250 mL min − 1 .…”