Production of α-amylase from Streptomyces sp. SLBA-08 strain using agro-industrial by-products

Approximately 1.5 trillion tons are the estimated yearly biomass production, making it an essentially unlimited source of raw material for environmentally friendly and biocompatible products transformed by microorganism, specially fungi and actinomycetes. Several lignocellulosic residues, such as sisal waste and sugarcane bagasse contain starch in their structures which could become important sources for the production of amylases. This study evaluated the production of amylolytic enzymes using Streptomyces sp. SLBA-08 strain, isolated from a semi-arid soil, according to their ability to grow on soluble starch as the sole carbon source. The effect of the carbon source (sisal waste and sugarcane bagasse) on α-amylase production was studied using submerged cultivations at 30 ºC. The highest level of α-amylase activity corresponded to 10.1 U. mL-1 and was obtained using sisal waste (2.7%) and urea (0.8%) in submerged fermentation after 3 days of cultivation. The partial characterization showed the best α-amylase activity at 50ºC and pH 7.0. These results are of great importance for the use of sisal waste as a substrate for biotechnological proposes

Low‐temperature tolerance in coprophagic beetle species (Coleoptera: Scarabaeidae): implications for ecological services

1. Low temperatures affect insect functioning and population dynamics. Although temperate species cope with low temperatures better than their tropical counterparts, increasing temperature variability due to climate change exposes tropical species to frequent cold stress. For keystone insect species providing important ecosystem services, low-temperature tolerances, and behavioural responses remain unknown, hampering predictions under climate change. 2. The present study examined low-temperature physiology [critical thermal minima (CTmin) and chill coma recovery time (CCRT)] of six dung beetle species across three activity times: diurnal Allogymnopleurus indigaceous (Reiche) and Euoniticellus intermedius (Reiche); crepuscular Onthophagus alexis (Klug) and Onthophagus gazella (Fabricius), and; nocturnal Copris elephenor (Klug) and Scarabaeus zambezianus (Peringuey). Further, ecological service delivery (dung removal) was examined between diurnal and nocturnal species across the temperature regimes. 3. Nocturnal species had significantly greater cold tolerance than both crepuscular and diurnal species, while CCRT was significantly shortest in diurnal than both crepuscular and nocturnal species. Dung ball production between diurnal and nocturnal species interacted with temperature, with diurnal species producing significantly fewer balls at low temperatures, while nocturnal beetles were not significantly affected. In turn, nocturnal species produced significantly larger balls than the diurnal species across temperatures. Effects of temperature regime shifts were intertwined with the foraging ecology of individual species. 4. Future research should quantify species' functional responses toward different amounts of dung masses as stressful temperatures increase. 5. Results are significant for determination of species thermal ranges and predicting costs of low-temperature stress through reduced ecological services under shifting thermal environments