Formation of Stable Bdelloplasts as a Starvation-Survival Strategy of Marine Bdellovibrios

Abstract

Several wild-type isolates of marine bdellovibrios formed stable bdelloplasts when they infected gramnegative bacterial prey under certain culture conditions. Synchronous predator-prey cultures and low nutrient concentrations increased the yield of stable bdelloplasts. The bdellovibrio cells retained in the stable bdelloplasts showed a high survival capacity in nutrient-depleted saline solution (10% viable Bdellovibrio cells after 3 months at 25°C), whereas Bdellovibrio attack-phase cells kept under the same starvation conditions lost viability more quickly (1% viable cells after 48 h). The addition of yeast extract to a stable bdelioplast suspension induced lysis of the bdelioplasts and release of motile infecting attack-phase Bdellovibrio cells. Other substances, such as free amino acids, protein hydrolysates, NH4+, carbohydrates, and organic amines, did not induce such a release. Stable bdelloplasts were highly hydrophobic and had a lower endogenous respiration rate than attack-phase cells. In general, stable bdelloplasts were almost as sensitive to temperature changes, desiccation, sonication, tannic acid, and Triton X-100 treatment as attack-phase cells. Electron microscopy of stable bdelloplasts did not reveal any extra cell wall layer, either in the bdelloplast envelope or in the retained Bdellovibrio cells, unlike the bdellocysts of the soil bacterium Bdellovibrio sp. strain W. We propose that formation of stable bdelloplasts is a survival strategy of marine bdellovibrios which occurs in response to nutrient-and prey-poor seawater habitats.

Biotechnological Potential of Bdellovibrio and Like Organisms and Their Secreted Enzymes

“…Markelova also suggested that under unfavorable conditions B. bacteriovorus cells are able to persist inside surface-attached bdelloplasts, which protect them from the environment. The formation of stable bdelloplasts as a survival strategy was in agreement with previous studies by Sánchez-Amat and Torrella (1990). Another wastewater pollutants that might have an impact on Delta-BALOs are surfactants.…”

Phagocytosis-like cell engulfment by a planctomycete bacterium

“…Dependence on phagotrophy can often result in starvation due to unstable food source. Therefore, certain predatory bacteria have developed specific resting forms to resist starvation 23,29 . However, we were unable to observe any ‘ Ca .…”

Insight into the Possible Use of the Predator Bdellovibrio bacteriovorus as a Probiotic

“…Ideally, Bdellovibrio strains could be found in every site where Gram-negative bacteria, representing their food supply, are present [ 35 , 37 , 38 , 40 , 43 , 44 , 45 , 46 , 47 , 48 ]. Predators seem to play an essential role as ecological balancers in the environment, shaping the microbial community [ 49 , 50 , 51 , 52 , 53 ]. As the knowledge of these microorganisms has increased, the diversity among isolates has required the classification of some groups into distinct species and genera.…”