Saprophyte in the context of "Extracellular digestion"

Pathogenic bacteria are bacteria that can cause disease. This article focuses on the bacteria that are pathogenic to humans. Most species of bacteria are harmless and many are beneficial but others can cause infectious diseases. The number of these pathogenic species in humans is estimated to be fewer than a hundred. By contrast, several thousand species are considered part of the gut flora, with a few hundred species present in each individual human's digestive tract.

The body is continually exposed to many species of bacteria, including beneficial commensals, which grow on the skin and mucous membranes, and saprophytes, which grow mainly in the soil and in decaying matter. The blood and tissue fluids contain nutrients sufficient to sustain the growth of many bacteria. The body has defence mechanisms that enable it to resist microbial invasion of its tissues and give it a natural immunity or innate resistance against many microorganisms.

Saprotrophic nutrition /sæprəˈtrɒfɪk, -proʊ-/ or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs (organisms which feed on decaying organic matter), and is most often associated with fungi (e.g. Mucor) and with soil bacteria. Saprotrophic microscopic fungi are sometimes called saprobes. Saprotrophic plants or bacterial flora are called saprophytes (sapro- 'rotten material' + -phyte 'plant'), although it is now believed that all plants previously thought to be saprotrophic are in fact parasites of microscopic fungi or of other plants. In fungi, the saprotrophic process is most often facilitated through the active transport of such materials through endocytosis within the internal mycelium and its constituent hyphae.

Various word roots relating to decayed matter (detritus, sapro-, lyso-), to eating and nutrition (-vore, -phage, -troph), and to plants or life forms (-phyte, -obe) produce various terms, such as detritivore, detritophage, saprotroph, saprophyte, saprophage, and saprobe; their meanings overlap, although technical distinctions (based on physiologic mechanisms) narrow the senses. For example, biologists can make usage distinctions based on macroscopic swallowing of detritus (as in earthworms) versus microscopic lysis of detritus (as with mushrooms).

Xanthomonas campestris is a gram-negative, obligate aerobic bacterium that is a member of the Xanthomonadaceae, a family of bacteria that are commonly known for their association with plant disease. This species includes Xanthomonas campestris pv. campestris, the cause of black rot in brassicas (cruciferous vegetables), one of the most important diseases of brassicas worldwide.

These bacteria are facultative saprophytes, meaning that they are typically parasitic while also having the ability to live on dead or decaying organic matter under the proper conditions. Upon initial infection, the bacteria remain in the epiphytic stage; however, the harmful endophytic stage is reached when the bacteria actually enter the plant host through natural openings. In general, the genes that contribute significantly to the plant-bacteria relationship are the avirulence (avr) genes, the hypersensitivity response and pathogenicity (hrp) genes, and the pathogenicity factors (rpf) genes. Additionally, the virulence determinants associated with the seedborne diseases that result from this bacterium include extracellular enzymes, polysaccharides, lipopolysaccharides, etc.