Bacterial Metal-Scavengers Newly Isolated from Indonesian Gold Mine-Impacted Area: Bacillus altitudinis MIM12 as Novel Tools for Bio-Transformation of Mercury

Selikat river, located in the north part of Bengkulu Province, Indonesia, has critical environmental and ecological issues of contamination by mercury due to artisanal small-scale gold mining (ASGM) activities. The present study focused on the identification and bioremediation efficiency of the mercury-resistant bacteria (MRB) isolated from ASGM-impacted areas in Lebong Tambang village, Bengkulu Province, and analyzed their merA gene function in transforming Hg2+ to Hg0. Thirty-four MRB isolates were isolated, and four out of the 34 isolates exhibited not only the highest degree of resistance to Hg (up to 200 ppm) but also to cadmium (Cd), chromium (Cr), copper (Cu), and lead (Pb). Further analysis shows that all four selected isolates harbor a merA operon-encoded mercuric ion (Hg2+) reductase enzyme, with the Hg bioremediation efficiency varying from 71.60 to 91.30%. Additionally, the bioremediation efficiency for Cd, Cr, Cu, and Pb ranged from 54.36 to 98.37%. Among the 34, two isolates identified as Bacillus altitudinis possess effective and superior multi-metal degrading capacity up to 91.30% for Hg, 98.07% for Cu, and 54.36% for Cr. A pilot-scale study exhibited significant in situ bioremediation of Hg from gold mine tailings of 82.10 and 95.16% at 4- and 8-day intervals, respectively. Interestingly, translated nucleotide blast against bacteria and Bacilli merA sequence databases suggested that B. altitudinis harbor merA gene is the first case among Bacilli with the possibility exhibits a novel mechanism of bioremediation, considering our new finding. This study is the first to report the structural and functional Hg-resistant bacterial diversity of unexplored ASGM-impacted areas, emphasizing their biotechnological potential as novel tools for the biological transformation and adsorption of mercury and other toxic metals.

EXPLORATION ON STUDENTS’ UNDERSTANDING LAYERS IN SOLVING ARITHMAGON PROBLEMS

The research aims at exploring the characteristics of ‘don’t need’ boundaries of students in solving arithmagon problems using qualitative descriptive approach. The participants win this research are 23 eight-grader junior high school students. The research used the instruments including test questions and unstructured interviews. The data collection procedure began with giving test questions to 23 participants. All of them could make mathematical diagrams/drawings/model precisely according to the information presented from the problem. The student who used effective and clear sentences in solving problems though could not solve the problem in a structured manner is called as Subject 1 (S1).  The student who did not use effective and clear structured sentences is called as Subject 2 (S2). The student who used effective and clear sentences as well as structured in solving problems is called Subject 3 (S3).  This research used triangulation method by exploring data obtained from the test and interview results. According to the research result, it is concluded that S1 crossed the first ‘don’t need’ boundaries when solving the addition and multiplication arithmagon problems. S2 crossed the first and second “don’t need” boundaries when solving addition arithmagon problem and only crossed the first ‘don’t need’ boundaries in solving multiplication arithmagon problems. However, S3 crossed the second ‘don’t need’ boundaries in solving arithmagon problem of addition and multiplication. Through this research, it is hoped that further research will be able to find and explore the third ‘don’t need’ boundaries in solving mathematical problems.

Relationship between Environmental Factors and Rheumatic Heart Disease

Background. Rheumatic fever (RF) and rheumatic heart disease (RHD) are the most common acquired heart diseases in children. Environmental factors have been reported to play an important role in RHD’s prevalence Aim. The main purpose of this study is to assess the associations between environmental factors and RHD in children. Methods. A case control study was conducted in the Department of Child Health, Haji Adam Malik Hospital from April to June 2017. The case group consisted of children aged 5-18 years with RHD while control group consisted of healthy children. Demographic, anthropometric, and laboratory data were collected along with environmental factors. Statistical analysis was done using Statistical Product and Service Solution (SPSS). A P value of <0,05 with 95% confidence interval was considered significant. Results. A total of 39 children were enrolled in each group. Subjects’ father who only went to elementary and junior high school had a higher risk of having children with RHD (OR 28; p = 0.032 and OR 15.75; p = 0.011, respectively). Subjects’ mother who only went to junior high school had 7 times higher risk of having children with RHD (p = 0.026). Low monthly income increased the risk of RHD (OR 3,68; p = 0,009). Tap water usage, meat consumption more than once per week, and feasibility to buy clothes >1 pair per year decreased the risk of RHD at 0,31 (p = 0,013), 0,3 (p = 0,016), and 0,04 times (p <0,001) respectively. Conclusion. Parent’s education, monthly family income, water source, frequency of meat consumption, and feasibility to buy clothes are related to RHD in children.