Publications

3530

The ability of ruminants to utilize cellulosic biomass is a result of the metabolic activities of symbiotic microbial communities that reside in the rumen. To gain further insight into this complex microbial ecosystem, a selection-based batch culturing approach was used to identify candidate cellulose-utilizing bacterial consortia. Prior to culturing with cellulose, rumen contents sampled from three beef cows maintained on a forage diet shared 252 Operational Taxonomic Units (OTUs), accounting for 41.6–50.0% of bacterial 16S rRNA gene sequences in their respective samples. Despite this high level of overlap, only one OTU was enriched in cellulose-supplemented cultures from all rumen samples. Otherwise, each set of replicate cellulose supplemented cultures originating from a sampled rumen environment was found to have a distinct bacterial composition. Two of the seven most enriched OTUs were closely matched to well-established rumen cellulose utilizers (Ruminococcus flavefaciens and Fibrobacter succinogenes), while the others did not show high nucleotide sequence identity to currently defined bacterial species. The latter were affiliated to Prevotella (1 OTU), Ruminococcaceae (3 OTUs), and the candidate phylum Saccharibacteria (1 OTU), respectively. While further investigations will be necessary to elucidate the metabolic function(s) of each enriched OTU, these results together further support cellulose utilization as a ruminal metabolic trait shared across vast phylogenetic distances, and that the rumen is an environment conducive to the selection of a broad range of microbial adaptations for the digestion of plant structural polysaccharides.

Citrus greening disease, recently known as huanglongbing disease, is known to wreak havoc not only in Nepal but across the globe as it is non-curable once trees are affected. In 1919, this disease was reported first time in China, most likely originating from Taiwan. It then spread to more than a hundred countries and was recorded in Nepal for the first time from Pokhara Valley in 1968. Till now, there is no established solution for this century-old and yet, newly evolving disease. Being a vector-borne bacterial disease, the use of antibiotics had been a practice on a large scale that had led to the development of resistance. This disease has been more challenging to the developing and least- developed countries like Nepal. Thus, this paper aims to solve the problems of all the farmers engaged in citriculture by making them aware of the best-integrated management approaches that would help them increase their productivity and ultimately contribute to food security and sustainability. Detailed information about the disease, together with various techniques for integrated management and control of this disease is in this review. Thus, this paper will help farmers, traders, and planners.