Shifting nutrient-mediated interactions between algae and bacteria in a microcosm: Evidence from alkaline phosphatase assay

Abstract

The impacts of different nutrient additions (N + P, N + P + C, 4N + P, 4N + P + C, N + 2P) on the growth of algae and bacteria were studied in a microcosm experiment. Since alkaline phosphatase activity (APA) provides an indication of phosphorus deficiency, the higher value for algal APA in the treatments with excess nitrogen and for bacterial APA in the treatments with excess carbon suggested that, algal and bacterial phosphorus-limited status were induced by abundant nitrogen and carbon input, respectively. Bacterial phosphorus-limited status was weakened due to higher bacterial competition for phosphorus, compared to algae. In comparison with the bacterial and specific bacterial APA, higher values of algal and specific algal APA were found, which showed a gradual increase that coincided with the increase of chlorophyll a concentration. This fact indicated not only a stronger phosphorus demand by algae than by bacteria, but also a complementary relationship for phosphorus demand between algae and bacteria. However, this commensalism could be interfered by glucose input resulting in the decline of chlorophyll a concentration. Furthermore, the correlation between bacterial numbers and chlorophyll a concentration was positive in treatments without carbon and blurry in treatments with carbon. These observations validate a hypothesis that carbon addition can stimulate bacterial growth justifying bacterial nutrient demand, which decreases the availability of nutrients to algae and affects nutrient relationship between algae and bacteria. However, this interference would terminate after algal and bacterial adaption to carbon input.

Effects of bacterial communities on biofuel-producing microalgae: stimulation, inhibition and harvesting

“…Competitive interaction for phosphorus between Scenedesmus acutus and its associated heterotrophic bacteria under low phosphorus conditions has been investigated in previous studies (Currie & Kalff, 1984;Gurung et al, 1999). The bacterial competition for phosphorus was acknowledged to be higher, compared to algae (Liu et al, 2012). The phosphate uptake in the low phosphorus conditions was proved to be dominated by bacteria rather than by algae (Zubkov et al, 2007).…”

How phosphorus limitation can control climate-active gas sources and sinks

“…To acquire nutrients from organic sources, phytoplankton organisms can directly ingest prey or particulate organic matter by phagotrophy (mixotrophy) or absorb dissolved organic matter by osmotrophy. When DIP is limiting, most phytoplankton organisms are also able to indirectly acquire P from dissolved organic P (DOP; e.g., sugar phosphates, phospholipids, nucleotide phosphates) by synthesizing ecto-enzymes that hydrolyze DOP to release DIP (Kuenzler and Perras, 1965;Cembella et al, 1984;Flynn et al, 1986;Hoppe, 2003;Glibert and Legrand, 2006;Liu et al, 2012). Alkaline phosphatase (AP) is one of the well-known enzymes responsible for the hydrolysis of DOP.…”

Influence of nitrate and dissolved organic carbon loading on the interaction of Microcystis aeruginosa and heterotrophic bacteria from hyper-eutrophic lake (Taihu Lake, China)

“…The growth of heterotrophic bacteria is easily limited by nutrient supply and dissolved organic carbon (DOC) produced by phytoplankton (Bratbak, 1985), while algae can also benefit from heterotrophic bacteria which may produce available nutrients through organic matter decomposition (Liu et al, 2012). Phytoplankton -i.e.…”