Problem-based learning (PBL) is a learning method based on the process between learning material to real life problems. The method has been widely applied and shown positive results on different subjects and education levels. In this paper, we discuss the application of PBL in mathematics education on several high schools in South East Asia countries, which include Indonesia, Thailand, Malaysia, Singapore, and Vietnam, considering that all of the countries had close cultural and geographical aspects. Researches on the application of PBL showed overall positive results to the high school mathematics education in all of the observed countries, with similar and distinctive objective and outcomes were found. In Indonesia, the application of PBL in mathematics education improve student’s learning activities aside from its positive contribution to the learning outcomes, while in Thailand, Malaysia, and Singapore, PBL contributes to the improvement of students’ higher-order thinking skills.

This study aims to determine the enzymatic activity of extracellular alkaline protease from Bacillus cereus TD5B and its potential application as a sheep skin dehairing agent. The B. cereus TD5B was screened for extracellular alkaline protease production on skim milk agar media, while its alkaline protease activity and the application were measured at 1%, 1.5%, and 2%. The application of alkaline protease from B. cereus TD5B as a sheep skin dehairing agent was observed through histological examination and physical properties measurement after chrome-tanning with lime and Na2S as control. The study was conducted in a completely randomized design, and the quantitative data were analyzed using Duncan’s Multiple Range Test. The results showed that a clear zone was seen surrounding B. cereus, indicating the bacteria’s proteolytic activity. The protease activity measurement showed that 2% of alkaline protease had the highest enzymatic activity at 144.75 U/mL/min. The highest tensile strength of sheep leather was obtained after dehairing at 1% alkaline protease concentration (350.26 kg/cm2), even though the highest elongation was obtained at 2% (34.92%). In contrast, different concentrations showed similar shrinkage temperatures at 90°C. This study concludes that the optimum alkaline protease concentration from Bacillus cereus TD5B as a sheep dehairing agent was 2%.

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