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.

Insight into Green Extraction for Roselle as a Source of Natural Red Pigments: A Review.

Roselle (Hibiscus sabdariffa L.) is a source of anthocyanins as red pigments that is extensively farmed in tropical and subtropical regions, including Indonesia, Malaysia, China, Thailand, Egypt, Mexico, and West India. The roselle plant contains a variety of nutrients, including anthocyanins, organic acids, pectin, etc. Due to the toxicity and combustibility of the solvents, traditional extraction methods for these compounds are restricted. Obtaining pure extracts is typically a lengthy procedure requiring many processes. Supercritical carbon dioxide (ScCO2) extraction as a green technology is rapidly improving and extending its application domains. The advantages of this method are zero waste production, quicker extraction times, and reduced solvent consumption. The ScCO2 extraction of natural pigments has great promise in food, pharmaceuticals, cosmetics, and textiles, among other uses. The ScCO2 technique for natural pigments may also be advantageous in a variety of other contexts. Due to their minimal environmental risk, the high-quality red pigments of roselle rich in anthocyanins extracted using ScCO2 extraction have a high sustainability potential. Therefore, the objective of this review is to increase knowledge related to the natural colorant of roselle as a substitute for chemically manufactured colorants using ScCO2 as a green method. This article covers ScCO2 extraction, particularly as it relates to the optimization of pigments that promote health. This article focuses on the high extraction efficiency of ScCO2 extraction. Natural colorants extracted via ScCO2 are regarded as safe compounds, especially for human consumption, such as novel functional food additives and textile and pharmaceutical colors.

Sustainability status, sensitive and key factors for increasing rice production: A case study in West Java, Indonesia.

The Indonesian rice production balance has managed to show a slightly consistent surplus recently, in the period of 2010 to 2021, but the country has continued to import rice to secure its rice reserve. The country has also made some efforts to increase its domestic rice production and, at the same time, faced ecological, socio-cultural, economic, institutional, and technological sustainability challenges. Previous studies on rice sustainability have shown varied results on the sustainability statuses and sensitive factors in Indonesia, yet there have been limited studies identifying key factors systematically. To provide more solid empirical evidence on this subject, a study to expand the scope to other sites with an additional analysis of the key factors is perceivably needed. This study aims to verify the sustainability status and identify sensitive factors as well as key factors for increasing rice production. The primary data were collected by interviewing officials from various agencies at the central and regional levels and several discussion groups of 40 participants, including farmers. In addition, secondary data were also collected from various ministries/agencies at the central and regional levels. Data analyses use a set of indicators, i.e., the Multidimensional Scaling (MDS) approach and the Matrix of Cross Impact Multiplications Applied to Classification (MICMAC) approach. The results show that the multidimensional sustainability status of increasing rice production in Bandung district is moderate, whereas sustainability status per dimension shows variations from poor to moderate. Fourteen out of 50 attributes are identified as sensitive factors influencing the sustainability of rice production. Six key factors are found to influence the sustainability of rice production. The study concludes that the sustainability status of increasing rice production in Bandung district is moderate, with variation across dimensions. The sustainability of increasing rice production in the study site is influenced by those 14 sensitive factors and those six key factors. This study recommends a number of major policies/programs to increase the sustainability of rice production, which are as follows: implementation of the Regional Spatial Plan, promotion of the application of best practices of farming management (organic fertilizers and pesticides), promotion of the use of agricultural machinery, and provision of farmer assistance for pre-harvest and postharvest production facilities, as well as farm financing. Future research should expand study sites to some other rice production centers with different attributes to enrich our understanding of the subject of rice sustainability.