Name: how microbes hunt and defend
Uploaded: 2026-03-12T13:57:44.000Z
Duration: 1 min 28 s
Channel: JoVE

미생물 포식은 미생물이 다른 미생물을 죽이고 섭취하여 영양분을 얻는 과정입니다.일부 포식성 박테리아는 그 전략에 따라 에피바이오틱 또는 엔데바이오틱으로 분류됩니다.뱀피로코커스와 같은 후생 포식자는 먹이의 외막에 부착해 용해효소를 분비하고, 방출된 세포질 물질을 흡수합니다.Bdellovibrio와 같은 내생 포식자는 먹이 세포에 부착하여 외막을 뚫고 주변 공간으로 들어가면서 생활사를 시작합니다.안으로 들어가면 포식자는 숙주를 구형 배상체로 변환합니다. 그 후 기체가 길어지고 복제되어 숙주를 해체시켜 자손을 방출합니다.마이코코커스는 다른 미생물을 포식할 수 있지만, 유기물에서도 부패적으로 성장합니다.포식 시 협동된 미소코커스 개체군은 활공 운동성을 이용해 먹이를 덮고 다가가 효소와 항생제를 방출해 먹이 세포를 용해합니다.포식성 원생동물은 박테리아를 먹으며 탄소와 에너지를 먹이망 위로 이동시키는 데 도움을 줍니다.방식을 막기 위해 박테리아는 종종 필라멘트, 미세 군집, 바이오필름과 같은 더 큰 구조를 형성합니다.

미생물 상호작용: 포식

Microbial Interactions: Predation

미생물 포식은 한 미생물이 다른 미생물을 죽이고 섭취하여 영양분과 에너지를 얻는 과정을 의미합니다. 박테리아와 원생동물 포식자 모두를 포함합니다. 이 상호작용은 미생물 군집을 형성하고 영양 순환을 조절하는 데 중요한 역할을 합니다.<h3>박테리아 포식자: 에피바이오틱 vs. 엔데바이오틱</h3>박테리아 포식자는 공격 방식에 따라 에피바이오틱 또는 내생 포식자로 분류됩니다. 뱀피로코커스와 같은 에피바이오틱 포식자는 먹이 세포 표면에 부착하여 프로테아제와 뉴클레아제 같은 가수분해 효소를 분비하여 숙주 세포를 용해시키고, 세포질 내용물을 방출하여 영양분 흡수를 돕습니다. 반면, Bdellovibrio bacteriovorus 와 같은 내생 포식자는 먹이 세포의 외막에 부착하여 주변 공간으로 침투함으로써 생활사를 시작합니다. 주변질질 공간 내에서 포식자는 길게 늘어나 복제하여 결국 숙주 세포를 분해하여 여러 자손을 방출합니다.<h3>점염구균에 의한 겸성 포식</h3>Myxococcus xanthus는 겸성 박테리아 포식자로, 유기물을 청소하는 것과 다른 미생물을 적극적으로 잡아먹는 것을 번갈아 가며 행동합니다. 활공 운동성을 이용해 협동된 맥초구균 개체군이 먹이를 향해 몰려들어 삼킨다. 이 군집은 미소비레신, 미살라마이드 같은 항균 화합물을 포함한 분해성 효소와 2차 대사산물을 분비하여 먹이 세포를 용해하고 경쟁자를 억제합니다. 이러한 협력적 행동은 박테리아 간의 사회적 포식을 대표하며, 세포 신호 전달 메커니즘에 의해 조절됩니다.<h3>원생동물 방목과 박테리아 방어</h3>포식성 원생동물—주로 이영양 편모동물과 섬모충—은 식세포작용을 통해 박테리아 집단을 갉아먹는다. 이 원생동물들은 미생물 먹이사슬을 통해 탄소와 에너지를 전달함으로써 필수적인 생태학적 역할을 합니다. 이에 대응하여 박테리아는 길게 뻗은 필라멘트, 군집된 미소 집단, 복잡한 바이오필름 형성과 같은 방어 전략을 자주 채택합니다. 이러한 구조적 적응은 물리적 보호를 제공하고 개별 세포의 접근성을 줄여 원생동물이 박테리아 표적을 삼키거나 침투하기 어렵게 만들어 방목 압력 하에서의 생존을 향상시킵니다.

Microbial predation refers to the process by which one microorganism kills and consumes another to obtain nutrients and energy. It encompasses both ...

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Education

교육

JoVE Core

Microbiology

미생물학

Unit

단위

Microbial Ecology

미생물 생태학

KEY TERMS AND CONCEPTS

주요 용어 및 개념

how microbes hunt and defend

Microbial predation is a form of interaction in which one microorganism kills and eats another to gain nutrients and energy. It includes both bacterial predators and protozoan predators. This process helps shape microbial communities and affects how nutrients move through the environment.

Some bacterial predators attack from the outside, while others enter the prey cell. Epibiotic predators, such as Vampirococcus, attach to the surface of a prey cell and release hydrolytic enzymes. These enzymes, including proteases and nucleases, break the host cell open so the predator can absorb the released cytoplasmic contents. Endobiotic predators, such as Bdellovibrio bacteriovorus, begin by attaching to the outer membrane of a prey cell and then moving into the periplasmic space.

Inside the periplasmic space, Bdellovibrio elongates and replicates. It then lyses the host cell and releases multiple progeny. Another bacterial predator, Myxococcus xanthus, can switch between scavenging organic matter and actively preying on other microbes. It uses gliding motility and coordinated swarms to move toward prey, engulf it, and release degradative enzymes and secondary metabolites.

Myxococcus swarms also produce antimicrobial compounds such as myxovirescin and myxalamide. These compounds help lyse prey cells and inhibit competitors. This group behavior is called social predation, and it is controlled by cell signaling. Protozoan predators, mainly heterotrophic flagellates and ciliates, graze on bacteria by phagocytosis, which is the process of engulfing cells. In the microbial food web, they transfer carbon and energy to higher levels.

Bacteria do not stay passive during grazing pressure. Many form elongated filaments, clustered microcolonies, or complex biofilms as defenses. These structures give physical protection and make individual cells harder for protozoans to engulf or penetrate. These adaptations can improve bacterial survival when predators are present.

How Microbes Hunt and Defend

introduction to microbial ecology

Microbial Communities in Soil and Extremes

Microbial ecology looks at how microorganisms live, interact, and adapt in different ecosystems. It also shows how these tiny organisms help shape nutrient cycling, energy flow, and environmental balance. An ecosystem includes living parts and non-living parts, and microbes respond to both. Microorganisms can form populations, which are groups of the same species living together at the same time. When populations from different species live and interact in the same place, they form a microbial...

ecological niche

Microbial Niches in Ecosystems

Microbial niches describe how microorganisms survive, grow, and interact in an ecosystem. A niche includes how a microbe gets resources, reproduces, and relates to other species in its environment. This idea helps explain microbial community dynamics, biogeography, and ecosystem function. A microorganism’s fundamental niche is the full range of conditions where it could survive, grow, and reproduce. These conditions include both biotic factors, such as living interactions, and abiotic factors,...

methods to assess microbial populations

Measuring Microbes in Samples

Measuring microbes in a sample helps scientists study health, ecology, and industry. Microbial counts can show how many cells are present, how diverse they are, and what they may be doing. To do this, researchers use both culture-based and molecular methods. A viable plate count is a classic culture method for estimating living microbes. The sample is first diluted step by step, then spread on nutrient agar plates. Each viable cell can grow into a visible colony, so the colonies can be counted.

methods to assess microbial communities

Measuring Microbial Diversity and Activity

Microbial communities include bacteria, archaea, and eukaryotic microorganisms. They live in many ecosystems and affect important environmental and biological processes. Scientists study these communities by looking at how many species are present, how many individuals each species has, and how evenly the species are spread out. Species richness is the number of different species in a sample. Species abundance is the relative amount of each species. Species evenness describes how uniformly the...

the winogradsky column

Microbial Layers Inside a Winogradsky Column

A Winogradsky column shows how microbial layers form in a simple, sealed ecosystem. It is a clear model for studying microbial ecology and how different metabolisms interact in sediment over time. The setup uses a transparent glass cylinder. Half of it is filled with sediment mixed with cellulose, such as shredded paper, calcium carbonate, and gypsum. The cellulose provides a carbon source. Calcium carbonate buffers pH, and gypsum supplies sulfate. The rest of the cylinder is filled with pond...

microenvironments

Microbial Niches in Tiny Habitats

Microorganisms live in tiny habitats called microenvironments. These spaces have their own physical and chemical conditions. Oxygen level, pH, temperature, light, and nutrient supply can all differ from the surrounding area. These local conditions strongly affect microbial growth, metabolism, and which species can live there. Microenvironments often have sharp gradients over very small distances. In soil, oxygen may be available at the particle surface but drop off just a few millimeters below.

microbial mats

Microbial Mats and Oxygen Gradients

Microbial mats are layered communities of microbes that grow in response to changes in light, oxygen, and nutrients. These ecosystems are highly organized, and different microorganisms live at different depths. Biofilms are the early stage of this growth and are only a few millimeters thick. Mature microbial mats can grow to centimeter scale and show clear vertical structure. This layered arrangement lets microbes fill separate niches within a very small space. In cyanobacterial mats from hot...

microbial interactions: mutualism

Mutualistic Partnerships in Nature

Mutualistic partnerships in nature show how two or more organisms can benefit from living together. These symbiotic relationships can be obligate, meaning the partners depend on each other, or facultative, meaning the association is helpful but not required. Mutualism helps support many ecosystem functions across land and water. One common example is the partnership between plant roots and mycorrhizal fungi, such as Rhizophagus species. The fungal hyphae grow into the root hairs and epidermis,...

microbial interactions: cooperation

Microbial Cooperation in Soil and Hosts

Microbial cooperation describes helpful interactions between different species. In these partnerships, microbes work together for one or mutual benefit. These interactions can shape ecosystems and evolution. They also play major roles in symbiosis and disease. One clear example involves the Gram-negative bacterium Xenorhabdus nematophila and the parasitic nematode Steinernema carpocapsae. Juvenile nematodes carry the bacteria in the soil and need an insect host to mature. When the nematode...

microbial interactions: predation

Microbial predation is a form of interaction in which one microorganism kills and eats another to gain nutrients and energy. It includes both bacterial predators and protozoan predators. This process helps shape microbial communities and affects how nutrients move through the environment. Some bacterial predators attack from the outside, while others enter the prey cell. Epibiotic predators, such as Vampirococcus, attach to the surface of a prey cell and release hydrolytic enzymes. These...

microbial interactions: competition

Microbial Competition and Niche Partitioning

Microbial competition shapes how bacteria and other microbes share space and resources. In shared environments, they compete for nutrients, space, or light. The strength of this competition depends on the environment, including nutrient levels, space limits, and how many microbial species are present. These interactions help determine the structure, function, and resilience of microbial communities. Microbial competition is usually grouped into exploitative competition and interference...

microbial interactions: parasitism

Microbial Parasites and Host Dependence

Microbial parasites depend on a host for nutrients and shelter, and this dependence often harms the host. In parasitism, only the parasite benefits. This is different from mutualism, where both organisms gain from the relationship. Microbial parasites are classified by where they live in or on the host. Ectoparasites stay on the host’s surface, such as the skin or outer tissues, and take in nutrients from outside. Endoparasites live inside the host’s body and invade tissues or organs.

microbe-plant interactions

How Plant Microbes Affect Growth

Plant microbes can help, harm, or simply live alongside their hosts. These microbe-plant interactions shape plant growth, health, and ecosystem function. The plant microbiome includes bacteria, fungi, archaea, protists, and viruses, and these organisms may live on the plant surface, inside plant tissues, or in symbiosis throughout the plant. Some of the most important beneficial partnerships involve mycorrhizal fungi. These fungi form close connections with roots and are grouped as arbuscular...

microbes and the carbon cycle

How Microbes Move Carbon Through Earth

Microbes move carbon through Earth’s major reservoirs and help drive the carbon cycle. Carbon shifts among the biosphere, lithosphere, atmosphere, and hydrosphere, where it supports life and helps regulate climate. It commonly cycles as carbon dioxide (CO2), the oxidized form of carbon, but methane (CH4) and organic compounds also matter. Photosynthetic microbes take in atmospheric CO2 and turn it into organic carbon. Cyanobacteria are especially important because they carry out oxygenic...

microbes and methanogenesis

How Microbes Produce Methane

Methane production in anaerobic ecosystems depends on methanogenic archaea and the microbes that work with them. This process happens where oxygen is absent, such as wetlands, sediments, and animal gastrointestinal tracts. In these anoxic habitats, aerobic respiration cannot run, so microbes use other pathways to break down organic matter. Anaerobic decomposition starts when cellulolytic bacteria, or cellulose-digesting bacteria, hydrolyze dead organic material into simple sugars. Other...

microbes and the nitrogen cycle

Microbial Steps in the Nitrogen Cycle

Microbes drive the nitrogen cycle by changing nitrogen into forms that plants and other organisms can use. This biogeochemical cycle keeps nitrogenous compounds balanced in ecosystems. It also supports plant growth and microbial growth. Nitrogen fixation begins the cycle by converting inert atmospheric nitrogen gas, N2, into ammonia, NH3. This step depends on nitrogenase enzymes. Free-living diazotrophs do this on their own. Aerobic bacteria such as Azotobacter spp. and anaerobic bacteria such...

microbes and the sulfur cycle

Sulfur Cycling Through Microbial Reactions

Sulfur cycling depends on microbial reactions that move sulfur through rocks, water, soil, and the air. In Earth systems, sulfur shifts among inorganic forms such as sulfate, elemental sulfur, and sulfide. These changes happen through both abiotic processes and biological activity in oxic and anoxic environments. Sulfate is the most oxidized form of sulfur. It is stored mainly in rocks, marine sediments, and ocean water, where it acts as a long-term reservoir in the global sulfur cycle. In...

microbes and other elemental cycles

Microbes Driving Iron and Manganese Cycles

Microbes drive iron and manganese cycling in aquatic environments by changing these metals between reduced and oxidized forms. These reactions are especially important along redox gradients, where oxygen levels shift across stratified water layers. The microbes use these metals for energy, growth, and structural needs. In oxygen-rich surface waters, iron is usually present as insoluble ferric iron, Fe(III). Some bacteria release siderophores, which are small organic molecules that bind ferric...

marine microbial ecology

Microbial Life in the Ocean

Marine microbial life is shaped by salinity, low nutrients, and changing oxygen levels. These physical and chemical limits influence which microbes can survive and how they function. They also affect how ocean microbes help drive nutrient and carbon cycling. Small cell size is common in these environments because it gives microbes a larger surface-to-volume ratio. That helps them take up nutrients more efficiently when nutrients are scarce. In estuaries, where salinity changes often,...

deep sea microbial ecology

Deep Sea Microbes and Extreme Conditions

Deep sea microbes live in one of Earth’s harshest environments. The deep ocean is far below the sunlit photic zone, which usually reaches the upper 100 to 200 meters of open water. Below that layer, the bathypelagic and abyssal zones stretch from about 1,000 to 6,000 meters, and hadal trenches go even deeper. This region is dark, cold, and highly pressurized. Temperatures are usually around 2 to 3°C, although hydrothermal vents can be slightly warmer. Pressure rises by about 1 atmosphere for...

freshwater microbial ecology

Microbes in Streams, Lakes, and Rivers

Freshwater microbes live in streams, rivers, lakes, ponds, and marshes, but their communities change with water movement, light, depth, and nutrients. These systems are often grouped into lotic waters, which flow, and lentic waters, which are still or slow-moving. The physical setting shapes where microbes grow and how they get energy. In lentic systems, phytoplankton are the main producers. They make autochthonous organic carbon, which means carbon made within the water body. In lotic...

soil microbial ecology

How Soil Microbes Cycle Nutrients

Soil microbes drive nutrient cycling, organic matter turnover, and ecosystem stability. A gram of soil can contain thousands of bacterial and archaeal taxa, but their shared job is what helps sustain land ecosystems. Their activity changes the way carbon, nitrogen, and other nutrients move through soil. Soil is a patchwork of minerals, organic matter, water, and air. Microbes live in tiny microhabitats shaped by pore size, moisture, oxygen, and nutrients. Sandy soils drain fast and tend to...

key terms and concepts

Learn how bacterial and protozoan predators kill, consume, and graze on microbes, and how bacteria defend themselves with filaments, microcolonies, and biofilms.

How Microbes Hunt and Defend | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

microbiology

How Microbes Hunt and Defend

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