SUMMARYNine volatile hydrocarbons, as well as methyl chloride, carbonyl sulphide and carbon disulphide, have been identified by mass spectrometry as products of Agaricus bisporus in the compost used in commercial mushroom beds. Of these, only ethylene showed a pattern of production that could be correlated with developmental phases of the crop, high levels being produced whenever fruit bodies were rapidly enlarging.In laboratory flask cultures, under controlled conditions, high levels of ethylene occurred whenever young fruit bodies entered the expansion phase. The enhanced rate of ethylene production continued over several days, irrespective of whether fruit bodies were removed. Production occurred within the colonized compost; no ethylene was evolved by the fruit body itself.When the first fruit bodies expanded, either in beds or culture flasks, laccase levels in the compost fell and those of a P-1,4-glucanase (cellulase) rose. The enzyme switch occurred once only, during maturation of the first fruit bodies, whereas an elevated ethylene production was associated with each occasion when fruit body maturation took place.The low level of laccase and high level of cellulase characterized the whole of the reproductive stage of A. bisporus, whereas the phasic periods of high ethylene production distinguished between periods of fruit body maturation and intervening resting periods. I N T R O D U C T I O NAgaricus bisporus (Lange) Sing., the cultivated mushroom, has two phases in its life history : a vegetative mycelial phase, followed by a reproductive, fruit body-forming phase. The change from one phase to the other occurs as a result of covering colonized compost with a layer of non-sterile peat or soil, mixed with lime, known as 'casing soil'. This results in the formation of fruit body initials which develop some days later into mature mushrooms. Despite numerous studies, the factors which control initiation and development are still not clearly defined. Eger (1972) showed that bacteria in the casing play an essential though unknown role in initiation. Mader (1943) and Sinden (quoted by Schisler, 1957) considered the involvement of volatile substances in the control of development, and the importance , 1962), but their production has not, so far, been linked to a particular stage of development. E. M. T U R N E R , M . W R I G H T , T. W A R D , D . J. O S B O R N E A N D R. S E L FIn higher plants, ethylene is a naturally produced growth regulator controlling many aspects of development (Abeles, I 973). A number of other unsaturated hydrocarbons (acetylene, propene) will also modify plant growth in a similar way, but at much higher concentrations.With the view that similar controls may exist in fungi, we have examined the production of ethylene and other hydrocarbon volatiles during the life cycle of A . bisporus both in normal commercial beds and in the controlled conditions of laboratory cultures. We report the identification of these volatiles, and set out evidence from which we conclude that a high and ph...
ABSTRACT:Chlamydia pecorum, a recognized pathogen of domesticated ruminants and koalas (Phascolarctos cinereus), has been recently reported in a broad range of other wildlife species including water buffalo (Bubalus bubalis), ibex (Capra ibex), chamois (Rupicapra rupicapra), red deer (Cervus elaphus), and birds. This identification raises questions as to whether cross-host transmission may be a factor in the epidemiology of infections in these species. To begin to address this question, we employed a C. pecorum species-specific multilocus sequence typing (MLST) scheme to characterize a small collection of C. pecorumpositive samples from wild, free-range ibex, a chamois, and a red deer from Grison, Switzerland, a canton where domesticated and wild ruminants graze in close proximity during the summer. Screening by PCR confirmed low to moderate levels of Chlamydia pecorum DNA in the eyes of healthy ibex (n54) and in the deer fecal sample (n51). The MLST analysis revealed three novel sequence types (STs; 88, 90, and 89) in these samples. On phylogenetic analysis, the ibex and deer sequences clustered by host species in their own well-supported clades and away from C. pecorum STs found in other hosts. Even though the analyzed sample size was small, the identification of unique C. pecorum STs infecting free-ranging Alpine ibex and red deer provides useful information for further C. pecorum epidemiologic studies.
Heat haze-forming proteins are stable during winemaking and are typically removed via adsorption to bentonite. Proteolytic degradation is an alternative method to prevent wine-haze and offers the opportunity to reduce the environmental impacts and labor cost of the process. Herein, we describe the development of a production system for Botrytis cinerea proteases for the enzymatic degradation of heat haze-forming proteins. The effect of culture medium on the secretion of glucan by B. cinerea was investigated and methods to inactivate B. cinerea laccase in liquid culture medium were assessed. Protease production by B. cinerea was scaled up from 50 mL in shake flasks to 1 L in bioreactors, resulting in an increase in protease yield from 0.30 to 3.04 g L−1. Glucan secretion by B. cinerea was minimal in culture medium containing lactose as a carbon source and either lactic or sulfuric acid for pH control. B. cinerea laccases were inactivated by reducing the pH of culture supernatant to 1.5 for 1 h. B. cinerea proteases were concentrated and partially purified using ammonium sulfate precipitation. SWATH-MS identified aspartic acid protease BcAP8 amongst the precipitated proteins. These results demonstrate a simple, affordable, and scalable process to produce proteases from B. cinerea as a replacement for bentonite in winemaking. Key points • Isolates of B. cinerea that produce proteases with potential for reducing wine heat-haze forming proteins were identified. • Media and fermentation optimization increased protease yield tenfold and reduced glucan secretion. • Low pH treatment inactivated laccases but not proteases. Graphical abstract
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