Revista de bioprocesamiento y biotecnologías

Leaf nutrients have an important role in governing the trees growth and development of trees and are sources of nutrients for ruminants in forest. The present paper makes a synthesis of two earlier studies undertaken on macro and micronutrients of 1) 37 woody species and 2) 44 medicinal plants used traditionally of Northeastern Mexico. In the both the studies we estimated the contents of six nutrients in the leaves, three macronutrients (P, Mg, K, protein, C, N, C/N and three micronutrients (Cu, Fe, ZN) both for woody species and medicinal plants. A large variability exists in nutrient contents in woody species and medicinal plants. The species selected for the highest macronutrients and micronutrients may be utilized for confirming their physiological efficiency and probable better growth and productivity as well as good sources of macro and micronutrients for grazing wild animals. Similar to the results of woody trees, medicinal plants also exhibited a wider variability in macro and micronutrients. Based on the analysis of macro and micro nutrients the following species Phalaris canariensis, Eruca sativa, Ocimum basilicum, Tragia ramosa, Mentha piperita, Mimosa malacophylla, Acalypha monostachya, Salvia hispánica, Tillandsia usenoides, Letsea glauscens, Tagetes lucida, Erygium heterophylla, Dyssodia setifolia, Nicotiana glauca, Ruta graveolens, Olea europea, Equisetum hyemale, Rosamrinus officinalis are selected containing a majority of each of these nutrients.

Background: The class Actinobacteria accounts for a high proportion of soil microbial biomass and more than half of the bioactive compounds including antibiotics, immunosuppressive agents, antitumor agents and industrial enzymes such as keratinases. Keratinases are modern proteases that can valorise poultry and leather industry wastes and may find applications in prion degradation and treatment of neurodegenerative diseases. A wide diversity of bacteria, actinomycetes and fungi are known to be keratin degraders. Manipur, being a part of Indo-Burma Hotspot, might harbor a rich diversity of bioactive actinomycetes. The objectives of the study are:

a) Isolation of new keratinolytic actinomycetes.

b) Medium optimization by statistical approaches for keratinase production.

Methods: A protease producing actinomycete strain from Hundung limestone quarry at Ukhrul, Manipur, India, was investigated for its keratinolytic activities. Optimization of keratinase production was done using statistical methods namely, Plackett-Burman Design (PBD) and Response Surface Methodology (RSM). Eleven (11) variables were screened using PBD.

Results: The strain showed keratinolytic activity with keratin azure and chicken feather as substrates. Maximum keratinolytic activity was observed at 40°C, pH 7 and 48 h of incubation. Yeast extract, MgSO₄, and corn flour were found to affect the response signal positively whereas glucose, CaCO₃, K₂HPO₄, NaCl and soyabean meal had negative effects. Yeast extract, cornflour, and soyabean meal were further studied using RSM. A 2.3 fold increase in keratinase production was achieved in submerged fermentation after the use of statistical optimization methods.

Conclusion: On the basis of biochemical properties and 16S rRNA gene sequence analysis, the strain was identified as Amycolatopsis sp. strain MBRL 40.

Novelty of the work: There are meagre reports of keratinolytic bacteria from limestone biotopes. In addition, keratinolytic Amycolatopsis species are scanty in the literature. This possibly is the first report of a keratinolytic Amycolatopsis strain from a limestone habitat.