Mixed inoculum

For the evaluation of preparations to be used against pathogenic fungi, suitable cultures of these pathogens should be used. To test substances intended to inhibit general contaminants, cultures of common fungi obtained conveniently by exposing Petri dishes of solid media to the atmosphere may be used, or alternatively dust or soil may be used as a source of a mixed inoculum. 

For effective and persistent disease management and biocontrol the need is to evaluate the mycorrhizal symbionts in the natural system under field conditions. The use of mixed inoculum of mycorrhizal symbionts can be more effective and give better results than use of a single species. Selection of superior indigenous mycorrhizal symbionts may have an adaptive advantage to the soils and environment in which pathogen and host co-occur as compared to non-indigenous mycorrhizal symbionts. 

In undefined mixed culture either the natural microflora of the substrate is allowed to develop or the substrate is inoculated with a mixed inoculum prepared by traditional methods. This type of process relies on the fermentation conditions to select for the desired microbial groups. Such processes are commonly used for traditionally prepared fermented foods and for waste treatment. 

Again, ISO 14851 had some predecessors, namely OECD 301C [15] and ISO 9408 [16]. Differences between the latter two procedures and ISO 14851 lie in flexibility of test conditions, source of inoculum and possibility for biomass determination. The test is often named after MITI (the Japanese Ministry of Trade and Environment) because they proposed the test to OECD. The OECD procedure prescribes the need to take inoculum from at least 10 (mostly aquatic) sources and make a mixed inoculum. 

A mixed inoculum of three fungi and two bacteria representing... 

To a 2-liter flask were added 300 g of finely divided corn. The flask and its contents were then sterilized and after sterilization 150 ml of sterile deionized water wereadded. To the mixture in the flask were then added 45 ml of the inoculum prepared by the process and the material was thoroughly mixed. The mixed material was then incubated for about 20 days at 25°C in a dark room in a water-saturated atmosphere. The following illustrates the recovery of the anabolic substance from the fermentation medium. 

The test is carried out in practice by mixing the appropriate volume ofthe solution under test with double-strength broth and making it up to volume with water as illustrated in Table 11.5. If the volume ofthe inoculum is greater than 1-3 drops, this must be compensated for in planning a table of dilutions. 

Biological. In activated sludge, 31.5% of the applied chlorobenzene mineralized to carbon dioxide after 5 d (Freitag et al., 1985). A mixed culture of soil bacteria or a Pseudomonas sp. transformed chlorobenzene to chlorophenol (Ballschiter and Scholz, 1980). Pure microbial cultures isolated from soil hydroxylated chlorobenzene to 2- and 4-chlorophenol (Smith and Rosazza, 1974). Chlorobenzene was statically incubated in the dark at 25 °C with yeast extract and settled domestic wastewater inoculum. At a concentration of 5 mg/L, biodegradation yields at the end of 1 and 2 wk were 89 and 100%, respectively. At a concentration of 10 mg/L, significant... 

Biological. Under aerobic conditions or in experimental systems containing mixed cultures, hexachloroethane was reported to degrade to tetrachloroethane (Vogel et al, 1987). In an uninhibited anoxic-sediment water suspension, hexachloroethane degraded to tetrachloroethylene. The reported half-life for this transformation was 19.7 min (Jafvert and Wolfe, 1987). When hexachloroethane (5 and 10 mg/L) was statically incubated in the dark at 25 °C with yeast extract and settled domestic wastewater inoculum for 7 d, 100% biodegradation with rapid adaptation was observed (Tabak et al, 1981). 

Often medicinal plants known from folk-lore are picked up and their extracts tested against known plant viruses by mixing them with the inoculum and doing half-leaf experiments. Each half of the leaf is rubbed with virus suspension. 

A sample of a standard calcium carbonate slurry was received from a large manufacturer in the USA. This sample was subjected to preservative efficacy testing according to the ASTM E 723-91 test protocol. Preservative treated samples were inoculated with a mixed bacterial inoculum containing organisms with a known tolerance or resistance to BIT (l,2-Benzisothiazolin-3-one). Untreated controls were included for reference purposes. The test procedure is outlined below. 

Known quantities of the mineral slurry were placed in two sterile containers and inoculated with the inoculum. The slurries were thoroughly mixed and 50 ml aliquots were dispensed into sterile, stoppered flasks or capped bottles. 

Inoculate each product container with one of the prepared and standardized inoculum suspensions and mix well. 

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