Rotifers as live feed microbial aspects, hygiene and preservation techniques

4 Rotifers as live feed microbial aspects, hygiene and preservation techniques 

As mentioned above, organic loads in rotifer cultures are very high. When the temperature is increased, high bacterial growth rates are obtained (Skjermo and Vadstein, 1993).This results in rotifers that carry a high bacterial load (e.g. 2.43 x 10 CFU/g wet weight rotifers for rotifers fed on a mixture of I. galbana and baker s yeast) (Nicolas et al, 1989 Munro et al, 1999 Hache and Plante, 2011). 

However, the bigger issue lies in the fact that rotifers can be vectors of fish/shrimp pathogens (see microbial community management below) (Nicolas et al, 1989 Muroga, 1995 Verdonck et al, 1997 Yan et /., 2007). On the other hand, bacteria can also have a positive effect towards rotifers as some produce vitamin (Yu et /., 1989) or enhance rotifer growth rate (Rombaut et al, 1999) (see below). 

As rotifers are able to hlter bacteria, the microbial community of the rotifers is defined by the microbial community present in the culture water. Selected bacteria can be added to the culture water in order to shift their microbial community towards one that results in a better performing culture (Gatesoupe et al, 1989 Rombaut et al, 1999) or to one that is beneficial for the predator (Gatesoupe, 1991). 

Probiotic bacteria (probiotic was defined by Verschuere et al (2000) as a live microbial adjunct which has a beneficial effect on the host by modifying the host-associated or ambient microbial coimnunity, by ensuring improved use of feed or enhancing its nutritional value, by enhancing the host response towards disease, or by improving the quality of its ambient environment) added at the start of the first batch culture were still retrieved after four consecutive batches of three days each. This was the case when rotifers were fed either solely N. oculata, a yeast-based diet, a mixture of both feeds fed simultaneously or fed every other batch (Qi et al, 2009b). 

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