Anaerobic fungi in the digestive tract of mammalian herbivores and their potential for exploitation

Abstract

Research into the microbiology of the rumen has been undertaken for many years with substantial contributions in bacteriology and protozoology being made during the 1940s, 1950s and 1960s. However, it was not until 1975that Orpin (1975 identified the rumen anaerobic fungi. In fact, zoospores of anaerobic fungi were known since the early part of this century but were mistakenly identified as protozoan flagellates in rumen fluid (Liebetanz, 1910). According to Warner (1966), these flagellates were sequestered on the rumen epithelium, moving to the rumen fluid when the animal was feeding. This hypothesis was necessary to account for the large increase in protozoan flagellates in rumen fluid immediately after feeding. Orpin (1975) showed that the sequestered cells were not on the rumen wall but came from digesta particles, concluding that their abundance after feeding was due to their liberation from digesta-associated fungal zoosporangia. Two reasons can account for our failure to recognize the existence of anaerobic fungi until the mid-1970s. First, there was the persistent belief that all fungi required 0, to grow (Foster, 1949) and second, it was common practice amongst rumen microbiologists to work with strained rumen fluid, discarding the digesta solids and, thus, the digesta-associated fungal thalli (Bauchop, 1983). Life history and survival

Advances in microbial ecosystem concepts and their consequences for ruminant agriculture

“…This will affect the development of biofilm communities, as will the physical structure of forage. Structurally complex lignocellulosic substrates undergo a complex and sequential microbial attack (Cheng et al, 1980), involving both bacteria and anaerobic fungi (Theodorou et al, 1996;Gordon and Phillips, 1998). Furthermore, the mechanical process of ingestive mastication increases the accessibility of dietary nutrients and increases the surface area available for microbial attachment and enzymatic attack (Bowman and Firkins, 1993;McAllister et al, 1994;Pan et al, 2003).…”

The rapid assignment of ruminal fungi to presumptive genera using ITS1 and ITS2 RNA secondary structures to produce group-specific fingerprints

“…The anaerobic fungi are an unusual group of zoosporic fungi occupying a unique niche in the digestive tract of wild and domesticated ruminants and large monogastric herbivores (Theodorou et al, 1996). Since their discovery in sheep in 1975 (Orpin, 1975), rumen microbiologists have been trying to establish the role played by these fungi in the digestive tract ecosystem.…”

“…analyses (Brookman et al, 2000a;Mennim, 1997). Six genera of fungi belonging to the order Neocallimastigales are now recognized, namely: Anaeromyces, Caecomyces, Cyllamyces, Neocallimastix, Orpinomyces and Piromyces (Theodorou et al, 1996;Ozkose et al, 2001).…”

The Enigmatic Universe of the Herbivore Gut

“…Strictly anaerobic fungi are an unusual group of zoosporic fungi that are a relative rarity in natural ecosystems, yet they are common in the gut of various herbivores (ruminants and large monogastric herbivores) [1]. In these environments, anaerobic fungi are elegantly tailored for the deconstruction of the food these animals eat: plant biomass.…”

“…Abbey D. Zuehlke 1 and Len Neckers 1, * Heat shock protein 90 kDa (Hsp90) is required for the activation and stabilization of numerous client proteins, but the functional requirements of individual clients remain Fungi. In bacteria, the cellulase and hemicellulase enzymes and proteins containing carbohydrate-binding modules (CBMs) are complexed to a scaffold protein (scaffoldin) via interactions between dockerin and cohesin molecules.…”