Oligotrophy vs. copiotrophy in an alkaline and saline habitat of Lonar Lake

Abstract

We reported our comparative observations on oligotrophs vs. copiotrophs from a hyper-alkaline and hypersaline habitat, Lonar Lake, situated in the Buldhana district of Maharashtra, India. Cell numbers of oligotrophic and copiotrophic microbes from the sediment were enumerated by the three-tube most probable number (MPN) method using an array of nutrient-rich and oligotrophic (≈10–20 mg carbon L−1) media offering simulated natural conditions of pH and salinity. A total of 50 strains from 15 different genera and 30 different species were isolated from the highest positive dilutions of MPN to identify the taxa of oligotrophs and copiotrophic microorganisms dominating in Lonar Lake. We did not get any true oligotrophs due to their adaptation to higher carbon levels during the isolation procedure. On the contrary, several true copiotrophs, which could not adapt and survive on a low-carbon medium, were isolated. It is also observed that changes in medium composition and nutrient level altered the selection of organisms from the same sample. Our data indicate that copiotrophic microorganisms dominate the eutrophic Lonar Lake, which is also supported by the past metagenomics studies from the same site. We also reported that quick depletion of carbon from oligotrophic medium worked as a limiting factor, inducing cell death after 2–3 generations and preventing the development of visible colonies on plates and sufficient optical density in liquid medium. Therefore, a long-term supply of low levels of carbon, followed by isolation on enriched media, can serve as a good strategy in isolation of novel taxa of microorganism, with industrial or environmental importance.

Novel oil-associated bacteria in Arctic seawater exposed to different nutrient biostimulation regimes

“…Unlike most other groups enriched in crude oil amended microcosms, Lacinutrix ASV30 exhibited a prominent response to crude oil addition regardless of whether the nutrient level was high, ambient or low (Figure 3). This aligns with characteristics of facultative oligotrophic bacteria capable of surviving in low-nutrient environments and adapting to higher levels of nutrients when they become available (71)(72)(73). This suggests that Lacinutrix ASV30 are versatile bacteria that may respond to oil spills in the Arctic marine environment even in the days prior to a biostimulation intervention (ambient nutrients), thereby potentially priming the population to continue or accelerate a bioremediation response after a biostimulation intervention (high nutrients).…”

Taxonomic and genomic attributes of oligotrophic soil bacteria

“…2A ). The genomes of bacteria inferred to be oligotrophs were more often generated through cultivation-independent methods than the genomes of copiotrophs, a pattern expected given the well-recognized challenges of cultivating and isolating oligotrophic taxa [ 29 , 30 , 72 ], further highlighting that cultivation-based methods are biased toward more copiotrophic taxa [ 4 ].…”

Extremely oligotrophic and complex carbon degrading microaerobic bacteria from Arabian Sea oxygen minimum zone sediments

“…Concurrently, though there was no growth for any of the nine isolates under the same conditions when incubation was started with a cell density of 10 6 CFU mL -1 , all the cultures retained around 10 4 or 10 5 CFU mL -1 from the 8 th day onward, till the 28 th day of incubation, when cell densities were last measured (Table S9). While similar responses to nutrient deprivation are common among microorganisms living in other oligotrophic ecosystems (Nimonkar et al 2022), for the inhabitants of carbon-impoverished marine deep subsurfaces, in situ metabolism, and thereby community size, is said to be balanced against the ambient flux of carbon and energy, with cells recalibrating their metabolic rates down to such bare minimum levels that are essential for system maintenance, survival, and long-term viability (Jørgensen, 2011). In the context of the ASOMZ sediments, however, it is noteworthy that extreme oligotrophy in all the nine isolates was critically affected by the availability of O 2 in the environment.…”