Author links open overlay panelSrobana Sarkar a 1, Pankaj Kumar Kumawat a 1, Randhir Singh Bhatt a, Artabandhu Sahoo a b
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Tainolytic bacteria were isolated from rumen contents of Malpura sheep.
Out of 24 isolates, 16 belonged to order Lactobacillales with taase activity ranging from 1.2-12.5 mol gallic acid/min.
Total cellulolytic enzyme activity (FPase) of the isolates ranged from 0.14 to 9.80 U/mL.
Isolated tainolytic strains effectively degraded Prosopsis cineraria leaves showing potential to be used as direct-fed microbials in ruminants for utilization of tain-rich fibrous feeds.
To counteract the negative effects of phytotains, ruminants host a diverse community of bacteria that break down tains. These bacteria not only possess tainolytic activity but also have other functional relevance that hasn't been properly examined. Therefore, the present study was conducted to isolate and characterize tain degrading bacteria (TDB) from rumen of sheep fed tain-rich diet with possible fibrolytic activity. Based on the development of a clear zone on tain-enriched agar plates, a total of 24 isolates were screened as tain hydrolyzing bacteria. Majority of the isolates were gram positive cocci. The isolates could tolerate phenolic monomers such as ferulic acid, gallic acid, vanillic acid up to 30 mM and pyrogallol up to 10 mM, while failed to grow in presence of syringic acid, p-coumaric acid and p-hydroxybenzoic acid. Highest and lowest taase activity was observed in TDB23 and TDB2 and TDB5 isolates, respectively. In terms of fibrolytic activity, maximum endoglucanase, exoglucanase, and FPase activity was observed for TDB9. In vitro digestibility of Prosopis cineraria leaves was considerably enhanced by inoculation of isolate TDB23 followed by TDB9. Therefore, the screened isolates demonstrated promising tain and fibre degrading potential as measured by their taase and fibrolytic enzyme activities, which can be further explored as direct-fed microbial in ruminants for effective utilization of tain-rich fibrous feeds.
Poor quality and insufficient feed supply are the main causes of low production in domesticated ruminants in arid and semiarid tropical regions (Kumawat et al., 2021). For grazing ruminants in semi-arid environments, native browsing foliages and shrubs make up a sizable share of supplemental feed resources. In addition to excessive lignification, the quantity of tains present in these foliages and forages often limits nutrient supply to the animals by making them biologically unavailable or interfering with the proliferation and activity of rumen microbes (Patra et. al., 2012; Choudhary et al., 2018). Tains are polyphenolic plant anti-nutritional substances that exert deleterious effects on livestock by interfering with the absorption of food protein, carbohydrates, minerals, and digestive enzymes causing reduced nutrient utilization (Bhat et al., 2013). Several studies have reported that dietary inclusion of tain rich feeds hampers animal productivity (Singh et al., 2011, Tseu et al., 2020). Reducing these substances at the animal level is more important because the elimination of plant secondary metabolites can negatively impact plants' defense mechanisms. Therefore, various strategies have been adapted in the recent years to reduce the tain content of feeds for better nutrient utilization in ruminants (Makkar et al., 2007).
A variety of unidentified microorganisms are present in the rumen microbiome, which can aid in the bioconversion and detoxification of various toxins present in feeds (Singh et al., 2011). Several microorganisms have been reported from the gastrointestinal tract of ruminants with the ability to degrade tains like Streptococcus bovis (Osawa and Sly, 1991), Lonepinella koalarum (Osawa et al., 1995), Clostridium sp (McSweeney et al., 1999) and Selenomonas ruminantium (Odenyo et al., 2001). Goel et al. (2007) reported significant taase activity in various strains of Group D streptococci (Enterococcus faecalis) isolated from goat faecal samples. Kumar et al. (2014) also reported tain tolerant bacterial isolates from rumen of goats fed oak leaves that were 99 to 100% related to Streptococcus gallolyticus. In addition to bacteria, tainolytic activity was also shown by anaerobic fungal isolates (Piromyces sp.) when ioculated to a media containing rumen buffalo rumen fluid and tain rich tree leaves (Paul et al., 2006). Nevertheless, tainolytic bacteria are more effective and fast degraders of natural tains than fungi (Goel et al., 2011). Strategies to enhance tain-tolerant bacteria in the rumen can improve the utilization of tain-rich foliage and forages in ruminants. Till date, studies primarily isolated tain-degrading bacteria from feces of ruminants, with limited characterization from the rumen and mostly focused on tainolysis capacity. Therefore, the present study was undertaken to isolate and characterize tainolytic bacteria from rumen contents of sheep fed tain rich diets as well as to assess the fibrolytic potential of the isolates in order to screen direct fed microbial additives that can synergistically improve the nutrient utilization of poor quality tain rich tropical feed resources in ruminants.
The present experiment was carried out in semi-arid regions of ICAR-Central Sheep and Wool Research Institute, Rajasthan, India. For the adaptive proliferation of tain degrading/adapting microbes in the rumen, 25 Malpura sheep were maintained on a taiferous diet consisting of Prosopsis cineraria (Total tains- 98.5, condensed tains- 62.2 and hydrolysable tains- 36.3 g/kg dry matter) and Zizipus numularia (Total tains- 60.4, condensed tains- 36.9 and hydrolysable tains- 26.3 g/kg
A total of 80 rumen content samples were included in the study. Out of 67 isolates of tain degrading bacteria, 24 isolates showing clear zones on agar plates containing taic acid as substrate were presumptively selected for further analysis and named as TDB1 - TDB24. The morphological and biochemical characteristics of the isolates are presented in Table 1. Most of the isolates were Gram positive except TDB1, TDB3, TDB13, TDB17, TDB21, and TDB24 which were Gram negative. Isolates were
Most of the isolates were cocci and diplococci morphologically, while others were rod-shaped bacilli. Similarly, Osawa and Mitsuoka (1990) and Goel et al. (2007) isolated diplococcic or chain of cocci from feces of koala and goat, respectively capable of degrading tain protein complex. Kumar et al. (2014) also reported tain degrading rod shaped coccobacilli from rumen of goats fed Quercus semicarpifolia leaves. Goel et al. (2015) isolated streptococci from cattle and reported that these
From the present findings it can be concluded that the tain degrading bacterial isolates from sheep rumen contents showed promising fibrolytic activity. Isolate TDB23 had high content of taase and FPase which synergistically improved the digestibility of tain rich Prosopis cineraria leaves. Hence, this isolates can be explored as direct fed microbes or trans-inoculants into other animal species for enhancing nutrient utilization of tain rich low quality feeds.
(Aguilar et al., 2007, Kumar et al., 2013)
Pankaj Kumar Kumawat: Methodology, Investigation. Srobana Sarkar: Writing – original draft, Project administration, Funding acquisition, Formal analysis, Data curation, Conceptualization. Artabandhu Sahoo: Writing – review & editing, Validation, Supervision, Project administration. Randhir Singh Bhatt: Visualization, Validation, Formal analysis, Data curation.
On behalf of all the authors, I declare that no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Authors are thankful to Director, ICAR-Central Sheep and Wool Research Institute, Avikanagar for providing necessary research facilities required during this study. The financial assistance provided by National Centre for Veterinary Type Cultures Network Project is gratefully acknowledged.
It is to certify that there is no actual or potential conflict of interest including any financial, personal or other relationships with other people or organizations within three years of begiing the
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نویسنده: فاطمه زارعی