Community structure and fibrolytic activities of anaerobic rumen fungi in dromedary camels

Abstract

Anaerobic fungi colonize the rumen and degrade cellulose and hemicellulose, which enable them to be key players in the lignocellulose fermentation. Consequently, an expansion of knowledge about rumen fungi could increase animal productivity, utilization of lignified forages like alfalfa hay, and enhance fibrolytic enzymes production. Here, we used an Internal Transcribed Spacer 1 (ITS1) clone library to investigate the anaerobic rumen fungi in camel and to investigate their ability to produce cellulase and xylanase in vitro. Rumen fluid was collected from camels fed Egyptian clover (n = 14), and wheat straw (n = 7) and fecal samples were collected from camels fed wheat straw and concentrates (n = 5), or natural grazing plants (n = 10). Neocallimastix and Cyllamyces were the most abundant anaerobic fungi in all camel groups. An anaerobic rumen fungi media containing alfalfa hay as a carbon source was inoculated by rumen and fecal samples to assess the ability of anaerobic rumen fungi in camel gut to produce cellulase and xylanase. The anaerobic gut fungi in the camel is diverse and has cellulolytic and xylanolytic activities, fungal culture from rumen samples of camel fed wheat straw (R2) exhibited highest cellulase production. In addition, many of the sequences in the current study have no equivalent cultured representative, indicating a novel diversity within the camel gut.

Peer Review #1 of "Comparative analysis of the metabolically active microbial communities in the rumen of dromedary camels under different feeding systems using total rRNA sequencing (v0.1)"

“…Moreover, the longer retention time and neutral pH in camel's forestomach (Russell and Wilson, 1996) make it more suitable for the survival of rumen fungi. Neocallimastix dominated the fungal community and was higher in the G1 camels, which was similar to other results on sheep and camels (Kittelmann et al, 2013, Rabee et al, 2019. This genus produces enzymes capable of hydrolyzing cellulose, xylan and starch (Pearce and Bauchop, 1985).…”

“…Camels (Camelus dromedaries) can produce milk and meat in hot, arid and semi-arid regions and can provide food security as the climate warms (Samsudin et al, 2011;Faye, 2013). Camels also provide textiles (fiber and hair) and are commonly used for transportation, agriculture, tourism, race and riding (Rabee et al, 2019). The unique feeding behavior and the functional structure of digestive tract of these pseudo-ruminants is well adapted to deserts (Kay et al, 1989).…”

“…For example, the protozoal community in camel rumen was studied heavily by conventional microscopic methods (Ghali et al, 2005;Baraka, 2012). Regarding the anaerobic fungi, a new fungal genus, Oontomyces was isolated from the rumen of Indian camel (Dagar et al, 2015), and only one study investigated whole fungal community in the gut of camel (Rabee et al, 2019). Only three molecular-based studies are available on the bacterial community (Samsudin et al, 2011;Bhatt et al, 2013;Gharechahi et al, 2015).…”

Characterization of Anaerobic Rumen Fungal Community Composition in Yak, Tibetan Sheep and Small Tail Han Sheep Grazing on the Qinghai-Tibetan Plateau

“…In addition, we found that the relative abundance of genera Piromyces and Neocallimastix were significant higher in Tibetan sheep in comparison to yak, suggesting that the Tibetan sheep have the relatively high ability to utilize recalcitrant material (cellulose and hemicellulose) considering these two genera are capable of producing cellulolytic and hemicellulolytic enzymes [46]. Additionally, many previous studies have discovered genus Neocallimastix was dominant in many ruminant species, such as American bison, sheep and llama [5,24,47], which was less abundant in the current study. This discrepancy in the fungal populations observed are inevitable as feeds and breeds of experimental animals affect population dynamics.…”

“…Recent studies on dairy cows have found that Caecomyces was the second most dominant genus [11,45], while in the present study, Piromyces was the second prevalent genus in the rumen, irrespective of animal species, but the relative abundance of genus Caecomyces was very low (0.76%). Previous study has reported that the genus Piromyces can produce cellulolytic and hemicellulolytic enzymes [46,47], while members (Caecomyces communis) belonging to genus Caecomyces had glycoside and polysaccharide hydrolase activity. This result indicates that such fibrolytic ruminal fungal strains are prevalent in grazing ruminants such as grazing yaks, Tibetan sheep and Small Tail Han sheep, and could be exploited as microbial feed additives to improved fiber utilization in ruminants from intensive farming.…”