<i>In vitro</i> fibrolytic activity of the anaerobic fungus, <i>Caecomyces</i> sp., immobilized in alginate beads

Abstract

In the present study, Caecomyces sp., an anaerobic rumen fungus from faeces of the Indian elephant, was immobilized using calcium-alginate. The resulting beads were found to solubilize within 4-5 h in culture medium at 39°C (pH 6.9), indicating their possible dissociation in the rumen, if used as a feed additive. Since media was also used as a component of the immobilization material, the fungi were not only found to survive, but also to grow, as mycelial growth was visible macroscopically on the surface of the beads. Incubation of immobilized fungi with wheat straw at different temperatures was found to extend the viability of immobilized fungi. Immobilization of rumen fungi and their subsequent incubation with an appropriate substrate (e.g., wheat straw, etc.) could be used to enhanced their survival, industrial use as propagules, and as direct-fed microbials/ feed additives for domesticated ruminants.

In vitro fibrolytic potential of anaerobic rumen fungi from ruminants and non-ruminant herbivores

“…Akin and Rigsby (1987) also observed three types of fungal colonies with a round extensive rhizomycelial network on the agar surface. Based on the further microscopic morphological characteristics such as the nature of growth, sporangia, rhizoids, and zoospore flagellation (Orpin 1975;Gold et al 1988; Barr et al 1989;Breton et al 1990;Li et al 1991;Ho et al 1993a, b;Thareja et al 2006;Tripathi et al 2007a;Chen et al 2007;Nagpal et al 2009), these 11 isolates were tentatively identified as Neocallimastix, Orpinomyces, Piromyces, Caecomyces, and Anaeromyces species (Table 1; Fig. 1).…”

“…Even though both polycentric and monocentric fungi were found in the rumen fluid of different animals, it was observed that monocentric fungi were prevalent in fecal samples. This could be attributed to the characteristic of polycentric fungi not being efficient spore-formers and therefore, they cannot survive for long in the feces, once outside the host (Davies et al 1993;Brookman et al 2000;Nagpal et al 2009). However, some polycentric fungi were also found in the fecal samples of cattle and buffalo, and this may highlight the presence of some dormant stage in the life cycle of polycentric fungi, suggesting that they are able to survive for considerable periods without any need for subculturing as a resting stage within the anaerobic environment of an animal's gut (Brookman et al 2000).…”

“…1 filter paper (6 9 1 cm & 50 mg), cellobiose, and xylan (from oat spelt; Sigma, Bangalore, India) separately, for assaying their carboxymethyl cellulose (CMCase), filter paper cellulase (FPase), cellobiase (Mandels et al 1976;Srinivasan et al 2001;Nagpal et al 2009), and xylanase (Kawaminami and Izuka 1970;Srinivasan et al 2001) activities, respectively, keeping one non-inoculated set as the control. Supernatants from the incubated cultures were analyzed for the estimation of reducing sugars (glucose and xylose), using a dinitrosalicylic acid method (Miller 1959).…”

“…Anaerobic fungi play a key role in plant-fiber degradation in the rumen, by releasing various enzymes such as cellulases, hemicellulases, proteases, and esterases, justifying their use as animal feed additives for improved ruminant nutrition (Lee et al 2004;Nagpal et al 2009). It is now well established that these ruminal fungi efficiently take part in fiber digestibility in ruminants, leading to a more rapid degradation of forage entering the rumen (Orpin and Joblin 1988;Lee et al 2004).…”

“…These fungi have been found in all of the geographic regions of the world, being ubiquitous in foregut fermenters and ruminants such as cattle, buffalo, and goats (Ho et al 1993a, b;Thareja et al 2006); red deer and impala (Bauchop 1979); and the wild bluebull (Boselaphus tragocamelus) (Paul et al 2004a;Tripathi et al 2007a); as well as in marsupials including kangaroos, wallaroos, and swamp wallabies (Breton et al 1989). These fungi have also been isolated from fecal samples of horses, zebras, donkeys, rhinoceroses, and Indian elephants (Breton et al 1990;Li et al 1990;Nagpal et al 2009), all of which are hindgut fermenters. Therefore, these fungi appear to be a standard part of the gut microflora in many herbivores that feed on a highly fibrous diet.…”