Pretti Sitompul ;::::::; THE ROLE OF RUMEN FUNGI IN FIBER DEGRADATION ______________ Pretti Sitompul

The Role Rumen Fungi In Fiber Degradation Secara umum, pakan ternak ruminansia terdiri dari sebagian besar rumput berserat berkualitas buruk, jerami dan produk agro-industri sampingan yang sulit dicerna dalam rumen secara alami. Oleh karena itu, upaya yang yang dilakukan untuk meningkatkan daya cerna makanan berkualitas buruk adalah dengan berbagai pakan aditif (Nagpal et al. 2007). Suatu hubungan positif yang jelas yang berhasil diamati adalah antara jumlah jamur fungi rumen dan asupan hijauan yang kecernaannya rendah menunjukkan kemungkinan memanfaatkan fungi sebagai pakan aditif dan probiotik untuk meningkatkan aktivitas mikroba.

(Lanjutan…) Fungi adalah konstituen penting dari mikrobiota rumen pada ternak yang mengandalkan pakan berkualitas rendah dan berserat. Fungi mendegradasi fragmen tanaman dalam rumen sapi dan herbivora lainnya. Melalui pertumbuhan rhizoidal, fungi menembus dinding sel tanaman dan meningkatkan area rentan terhadap serangan enzimatik.

Fungi rumen aktif menjajah dinding sel tanaman dan berjumlah hingga 8-12% dari biomassa mikroba dalam rumen (Rezaeian et al. 2004). (yang sebelumnya diasumsikan bahwa hanya bakteri dan protozoa yang aktif dalam hidrolisis biomassa tanaman.)

Fungi mencerna serat dengan menghasilkankan enzim sangat aktif : selulase, hemicellulases, xilanase, avicelases, glycosidases dll. Enzim ini ditemukan terkait dengan rhizomycelia (Williams et al. 1994; Lee et al. 2001).

Sejarah Penemuan Fungi Rumen The ruminal anaerobic fungi, reported as early as 1910, were thought to be flagellate protozoa and placed in the genera Callimastix, Sphaeromonas and Oikomonas. These flagellates were recognized as fungi for the first time in the 1970s (Orpin, 1975) with the first named species Neocallimastix frontalis. The flagellate zoospores encyst and germinate on ingested forage with radiating rhizoids that produce a single zoosporangium. In terms of lifecycle and morphology, N. frontalis is similar to members of Chytridiomycota and its fungal affinities are confirmed by chitin in the cell wall.

To date, the following list the genera and species of monocentric fungi: Neocallimastix frontalis, Neocallimastix patriciarum, Piromyces (formerly Piromonas) communis, Caecomyces (formely Spheromonas) communis, and Caecomyces equi.

Taxonomy Status Kingdom : Fungi Phylum : Neocallimastigomycota Class :Neocallimastigomycetes Order : Neocallimastigales Genera: A. Monocentric: Neocallimastix: zoospore with 4 - 20 flagella; thallus with filamentous branching rhizoids; Piromyces: zoospore with 1 - 4 flagella and thallus with filamentous branching rhizoids, and B.Polycentric: Orpinomyces: multiflagellate zoospores; Anaeromyces: zoospore with single flagellum; Cyllamyces: zoospore with 1 - 2 flagella with thalloid branched sporangiophore. Bulbous: Caecomyces: zoospores with 1 - 2 flagella; thallus with globular rhizoid; Cyllamyces: zoospore with 1 - 2 flagella, thalloid branched sporangiophores

Neocallimastix zoospore with 4 - 20 flagella; thallus with filamentous branching rhizoids; (sumber: Journals of Animal Science, 2012)

Piromyces: and thallus with filamentous branching rhizoids zoospore with 1 - 4 flagella and thallus with filamentous branching rhizoids Sumber: Journals of Animal Science, 2012)

Orpinomyces multiflagellate zoospores; Sumber: Journals of Animal Science, 2012)

Anaeromyces zoospore with single flagellum Sumber: Journals of Animal Science, 2012)

Anatomi Fungi Rumen Rhizoid Chyst Stalk Sporangium

(lanjutan..) Zoospores produced from sporangia swim to acceptable sites of colonization attach to the substrate, encyst, and develop a rhizoidal or rhizomycelial system that penetrates the plant wall and releases polysaccharidases against structural carbohydrates.

Let’s See… ILLUSTRATING BY ANIMATION (The Role of Rumen Fungi in Fiber Degradation) http://www.goatbiology.com/animations/digestion2.html

Metabolisme dan Fisiologi Jamur anaerobik memperoleh energi melalui fermentasi anaerob karbohidrat (Trinci et al. 1994). Sejumlah besar poli-, oligo-, dan monosakarida termasuk glukosa, selobiosa, fruktosa, maltosa, sukrosa dan xylose, mendukung pertumbuhan mereka (Orpin, 1975, 1976; Mountfort dan Asher, 1983; Phillips dan Gordon, 1988). Jamur anaerobik mengikuti profil fermentasi campuran asam mirip dengan enterobacteria seperti E. coli dengan konversi heksosa asetat, format, laktat, suksinat, etanol, CO dan H (Borneman et al. 1989, Trinci et al. 1994). Produk-produk ini dapat berfluktuasi antara 2 genera yang berbeda yaitu malat tinggi dan laktat oleh Anaeromyces spp. dibandingkan dengan Orpinomyces (Phillips dan Gordon, 1988).

Fermentation of cellulose by N. frontalis (Bauchop and Mountfort, 1981). Fermentation product mol/ 100 mol hexose Acetate 72.7 Lactate 67.0 Ethanol 37.4 Formate 83.1 Carbon dioxide 37.6 Hydrogen 35.3 Methane 0.0

Distribution First isolation in the UK from the rumen of sheep (Orpin, 1975) Have been found on almost all the continents and in all of the geographic regions, where there have been sought Ubiquitous among ruminants such as cattle, buffalo, goat (Singhal et al, 2000; Dey et al, 2004; Thareja et al, 2006)

(Bauchop et al, 1979; Singhal et al, 2000) contd… Red deer and impala (Bauchop et al, 1979; Singhal et al, 2000) Grey kangaroo, wallaroo and swamp wallaby (Breton et al, 1989) Fecal samples of hindgut fermenters such as ass, horse, elephant and zebra (Breton et al, 1990; Li et al, 1990) Isolated from fecal and rumen samples of wild Neelgai (Paul et al, 2004; Tripathi et al, 2007)

Role of anaerobic fungi in fibre digestion Role of rumen fungi in the degradation of plant fibre has been examined extensively (Lee et al, 2000; 2004; Samanta et al, 2001; Dey et al, 2004, Paul et al, 2004; Thareja et al, 2006; Tripathy et al, 2007) These fungi are better at penetrating plant tissue than are bacteria and protozoa (Orpin and Joblin, 1988) Such penetration leads to faster and more complete degradation of forage that enters the rumen. (Bauchop and Mountfort, 1981)

contd… Degradation of lignin-containing walls of plant cells is an important characteristic of rumen fungi (Mountfort et al, 1982; Akin and Benner, 1988) Rumen fungi dissolve small amounts of phenolic compounds from plant cell walls (Orpin, 1983; Gordon et al, 1985) Zoospores of many species appear to colonize the lignin-containing tissues preferentially and to establish colonies localized on sclerenchyma and xylem cells. (Akin et al, 1986)

contd… Anaerobic fungi penetrate the cuticle, a barrier that other microorganisms cannot cross. Rumen fungi attack recalcitrant plant cell walls by weakening the textural strength of the residue (Akin et al, 1989, 1990) The greater ability of rumen fungi to weaken forage fibre may be important in enhancing forage utilization by the host animal (Borneman and Akin, 1990)

contd… Increased digestibility of straw with use of different anaerobic fungi viz., Orpinomyces, Piromyces and Anaeromyces was observed (Manikumar et al, 2002; Sehgal et al, 2002; Tripathy et al, 2007) 7-12% increase in voluntary intake of straw based diet was reported when the sheeps were dosed with cultures of monocentric fungi (Gordon and Phillips, 1998) Fungal culture increased Cellulose degradation by 26% under in vitro environment. (Lee et al, 2004)

Fungi degrades plant cell wall: Xylem and mestome bundle sheath in leaves Schlerenchyma ring in stem Cuticular barrier of leaves (Bauchop et al., 1989)

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