Nitrates are not reduced nor is the Voges Proskauer reaction positive Some

Nitrates are not reduced nor is the voges proskauer

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type E. Nitrates are not reduced, nor is the Voges Proskauer reaction positive. Some carbohydrates, such as fructose and glucose, but not aesculin, cellobiose, dulcitol, glycogen, inulin, mannitol, melezitose, melibiose, raffinose, rhamnose, salicin, sorbose, starch, sucrose and xylose, are fermented to acetic and butyric acids. The G + C ratio of the DNA is in the range of 26 to 28 mol % (Cato et al, 1986). Eubacteriaceae representative Eubacterium tarantellae It was reported initially by Udey et al. (1976) that a novel anaerobic organism was capable of producing a neurological disease in striped mullet (Mugil cephalus). This conclusion resulted from an investigation into major fish mortahties in Biscayne Bay, Florida. The anaerobe was subsequently elevated to species status, as Eubacterium tarantellus (Udey et al, 1977), and then corrected to Eu. tarantellae (Triiper and
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Characteristics of the pathogens: Gram-positive bacteria 49 de'Clari, 1997). It seems likely that Catenabacterium, previously described as an anaerobic pathogen offish (Henley and Lewis, 1976), should probably be equated with Eu. tarantellae (Udey et aL, 1977). Euhac terium tar an tellae On BHTA, the organism produces flat, translucent colonies, approximately 2-5 mm in diameter, which are colourless, rhizoidal and slightly mucoid. These contain long, unbranched, filamentous. Gram-positive, asporogenous rods, which fragment into smaller bacilli of 1.3-1.6 x 1.0-17.0 |im. Good growth occurs at 25 to 37°C. All isolates degrade blood (P-haemolysis) and lecithin, but not aesculin, gelatin or starch. Catalase, H2S and indole are not produced; nitrates are not reduced; and carbohydrates are generally not fermented. However, there is some evidence for the production of acid from fructose, glucose and lactose, but not from aesculin, amygdalin, arabinose, cellobiose, maltose, mannitol, mannose, melezitose, raffinose, rhamnose, salicin, starch, sucrose, trehalose or xylose. Unfortunately, the G + C ratio of the DNA was not determined. From these char- acteristics, Udey et al. (1977) proposed that the organisms should be classified in a new species, as Eubacterium tarantellus. Clearly, the fish isolates possess the general characteristics o^ Eubacterium, i.e. Gram-positive, anaerobic, asporogenous, chemo- organotrophic, non-motile, catalase-negative rods, which grow well at 37°C (Moore and Holdeman-Moore, 1986). A comparison between the descriptions o^Eu. limosum and Eu. tarantellae reveals that, among comparative tests, there are similarities (Table 3.1). In fact, the only major differences concern hydrolysis of aesculin and acid production from lactose and mannitol. GRAM-POSITIVE BACTERIA—THE "LACTIC ACID" BACTERIA Carnobacteriaceae representative Carnobacterium piscicola (and the lactobacilli) There have been only a few reports citing Lactobacillus spp. as fish pathogens. The initial work was by Ross and Toth (1974), who described mortalities among 3-year- old rainbow trout in a hatchery in CaHfornia. The term pseudokidney disease was coined by these workers to distinguish the condition from BKD. However, it is not
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