Stimulative and inhibitory effects of bacteria on the growth of microalgae

Abstract

Several examples of stimulative and inhibitory effects of bacteria on microalgal growth are introduced, and the importance of bacteria in algal mass culture is investigated. Diatoms are often used as live food for planktonic larvae of sea urchin and bivalves. Monodispersed Chaetoceros ceratosporum has been cultivated by using clean, high nutrient content, deep seawater (DSW). However, the growth rate and cell yield of diatoms fluctuated, to relatively large extent, with the season that DSW was collected. When some bacterial strains isolated from DSW were added to the culture, diatom growth was often stimulated and a relatively constant cell yield was obtained. Another diatom species, C. gracilis, was also stimulated by adding some bacterial strains to cultures. The positive effect of bacteria on diatoms was observed not only for planktonic species, but also on attached species. A benthic diatom, Nitzschia sp., was stimulated by a bacterial film of Alcaligenes on the surface of the substratum. On the other hand, a strain of Flavobacterium sp. isolated from natural seawater during the decline period of an algal bloom had a strong algicidal effect on the red tide plankton, Gymnodinium mikimotoi. Recent reports demonstrate that many bacterial strains have significant algicidal effects on many species of red tide plankton. These results indicate that bacterial effects should be taken into account to obtain stable mass culture of food microalgae.

Probiotic Bacteria as Biological Control Agents in Aquaculture

“…Unicellular algae are often given as a first food or are included in the culture system as a food for rotifers and Artemia. Bacteria increase the growth rate and yield of algae (29,75,128). However, since bacteria may also inhibit algal growth (75), careful screening may be necessary when bacteria are to be used as probiotics in larval rearing or in the green-water technique.…”

Biofloc Technology (BFT): A Tool for Water Quality Management in Aquaculture

“…Inorganic ions are attracted to the surface of these biofilms and the solid surfaces of the substrate, promoting greater nitrification processes [27]. Some bacterial strains have a positive effect on microalgae growth not only for planktonic species but also on attached (benthic) species [28]. The extracellular polysaccharides of benthic diatoms may be used by heterotrophic organisms as carbon source [29].…”

Transformation of iodate to iodide in marine phytoplankton driven by cell senescence

“…Many phytoplankton cultures are often only available with their associated bacteria; diatoms in particular require the associated bacteria for normal growth (Fukami et al 1997, Croft et al 2005, Grossart & Simon 2007. Therefore, it is difficult to separate phytoplankton responses from those of the surrounding bacteria.…”