Effect of bacterial load and probiotics on the sustainability of microalgal cultures.

Kumar, Rajeev (2003) Effect of bacterial load and probiotics on the sustainability of microalgal cultures. Masters thesis, Central Institute of Fisheries Education.

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    Abstract

    This study entitled "Effect of bacterial load and probiotics on sustainability of microalgal cultures” was carried out with the objective of (1) investigating the bacterial diversity in microalgal cultures (2) to find out the bacterial load transferred to marine larval rearing systems via microalgal feeds and also (3) to study the effect of addition of a probiotic to microalgal cultures on its bacterial diversity, growth and sustenance. For fulfilling the objectives two experiments were devised and executed. In the first experiment two microalgal species, the flagellate tsochrysis galbana and the diatom Chaetoceros sp. were maintained as 250 ml cultures and their growth and bacterial diversity was measured. In the second experiment, the probiotic yeast Saccharomyces boulardii was added in lO* CFU/ml concentrations either as a single addition (Treatment SA) or as a daily addition (Treatment DA) to Chaetoceros species, culture. All treatments were made in triplicate and a control without addition of probiotic was maintained. The algal cell density in the culture flasks was taken daily and the total aerobic flora (on SWA), total vibrios (on TCBS) and total yeasts (on Sabouraud agar) were assessed on specific days. Results indicated that the experimental cultures showed all the typical phases of microalgal growth ie, lag, log, declining, stationary and death phases. The study shows that if microalgal cultures are used when they are In the log and stationary phase rather than in the declining phase, the amount of bacteria added to the larval culture medium can reduced by 3-4 orders of magnitude. All the measures of bacterial diversity except species richness showed and an increasing trend with increasing algal density in both Chaetoceros and Isochrysis galbana cultures. There was marked clustering of bacterial taxa during lag, early log. peak log and death phases in the microalgal cultures tested. The addition of the probiotic yeast S. boulardii in treatment SA resulted in significantly (P<0.01) improved algal growth rates with prolonged log and stationary period, when compared to control and treatment DA The mean total aerobic flora showed a steeply increasing trend in control and DA treatments, while the trend in SA treatment was that of slow increase. The hierarchical cluster analysis showed remarkable differences between treatments.There was a marked increase in the similarity percentage of bacterial clusters indicating a much better discrimation of bacterial taxa in treatment SA as compared to control.

    Item Type: Thesis (Masters)
    Uncontrolled Keywords: Bacterial load; Probiotics; Sustainability; Microalgal cultures
    Subjects: Dissertations
    Algae > Bacteria
    Aquaculture > Algal Culture
    Divisions: CMFRI-Kochi > Mariculture
    Subject Area > CMFRI > CMFRI-Kochi > Mariculture
    CMFRI-Kochi > Mariculture
    Subject Area > CMFRI-Kochi > Mariculture
    Depositing User: Mr Rakesh
    Date Deposited: 17 Sep 2016 04:38
    Last Modified: 06 Oct 2016 10:45
    URI: http://eprints.cmfri.org.in/id/eprint/11114

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