The biology of habitat dominance; can microbes behave as weeds?

Abstract

SummaryCompetition between microbial species is a product of, yet can lead to a reduction in, the microbial diversity of specific habitats. Microbial habitats can resemble ecological battlefields where microbial cells struggle to dominate and/or annihilate each other and we explore the hypothesis that (like plant weeds) some microbes are genetically hard-wired to behave in a vigorous and ecologically aggressive manner. These ‘microbial weeds’ are able to dominate the communities that develop in fertile but uncolonized – or at least partially vacant – habitats via traits enabling them to out-grow competitors; robust tolerances to habitat-relevant stress parameters and highly efficient energy-generation systems; avoidance of or resistance to viral infection, predation and grazers; potent antimicrobial systems; and exceptional abilities to sequester and store resources. In addition, those associated with nutritionally complex habitats are extraordinarily versatile in their utilization of diverse substrates. Weed species typically deploy multiple types of antimicrobial including toxins; volatile organic compounds that act as either hydrophobic or highly chaotropic stressors; biosurfactants; organic acids; and moderately chaotropic solutes that are produced in bulk quantities (e.g. acetone, ethanol). Whereas ability to dominate communities is habitat-specific we suggest that some microbial species are archetypal weeds including generalists such as: Pichia anomala, Acinetobacter spp. and Pseudomonas putida; specialists such as Dunaliella salina, Saccharomyces cerevisiae, Lactobacillus spp. and other lactic acid bacteria; freshwater autotrophs Gonyostomum semen and Microcystis aeruginosa; obligate anaerobes such as Clostridium acetobutylicum; facultative pathogens such as Rhodotorula mucilaginosa, Pantoea ananatis and Pseudomonas aeruginosa; and other extremotolerant and extremophilic microbes such as Aspergillus spp., Salinibacter ruber and Haloquadratum walsbyi. Some microbes, such as Escherichia coli, Mycobacterium smegmatis and Pseudoxylaria spp., exhibit characteristics of both weed and non-weed species. We propose that the concept of nonweeds represents a ‘dustbin’ group that includes species such as Synodropsis spp., Polypaecilum pisce, Metschnikowia orientalis, Salmonella spp., and Caulobacter crescentus. We show that microbial weeds are conceptually distinct from plant weeds, microbial copiotrophs, r-strategists, and other ecophysiological groups of microorganism. Microbial weed species are unlikely to emerge from stationary-phase or other types of closed communities; it is open habitats that select for weed phenotypes. Specific characteristics that are common to diverse types of open habitat are identified, and implications of weed biology and open-habitat ecology are discussed in the context of further studies needed in the fields of environmental and applied microbiology.

Characterization of Polish Phytophthora lacustris Isolates Obtained from Water Environments

“…Another aspect for explaining the yet unknown role of such ubiquitous microorganisms in the soil and water may be their dominant character through which they behave like weeds. The following characteristics could speak to the high competition among microorganisms: an exceptional vigor and number of propagules, no special requirements to nutrition, efficient nutrient acquisition, high tolerance to diverse stresses, production of stressful or toxic metabolites for other microorganisms, and more [40].…”

Production of biosurfactant by Wickerhamomyces anomalus PY189 and its application in lemongrass oil encapsulation

“…Biosurfactants alter microbial environments by their surface activity and antimicrobial activity that could help ensuring dominance of the habitat in nature by species such as W. anomalus 20 . Further understanding of this observation may lead to new means to enhance production of biosurfactants; for instance, a co-culture of W. anomalus with some ally or competitor microbe that triggers enhanced production of antimicrobial biosurfactant 21,22 .…”

Prevalence Acinetobacter spp. in Kemerovo Region Healthcare Settings

“…В последнее десятилетие частота инфек-ций, вызванных бактериями рода Acinetobacter, значительно увеличилась, описаны многочислен-ные вспышки в медицинских организациях [3][4][5]. Виды Acinetobacter являются убиквитарными, способны доминировать во многих экологиче-ских нишах [6], широко распространены в природе и обнаруживаются в илистой почве, на участках, загрязненных углеводородами, в сточных водах, а также на растениях (в том числе овощах), у жи-вотных и людей [7]. Acinetobacter spp.…”

“…Acinetobacter spp. способны ингибировать рост конкурирующих видов посред-ством секреции органических кислот, биосурфак-тантов, что в сочетании с мультирезистентностью к антимикробным препаратам определяет их вы-сокую способность к колонизации больничной среды и формированию госпитальных клонов [6]. Известно, что инфекции у людей, вызванные не-которыми представителями Acinetobacter spp., в основном приобретены после контакта с кон-таминированными медицинскими изделиями или в результате прямого контакта пациента с ме-дицинским персоналом [8].…”