Abstract. Sanjaya WTA, Khoirunnisa NS, Ismiani A, Hazra F, Santosa DA. 2021. Isolation and characterization of mercury-resistant microbes from gold mine area in Mount Pongkor, Bogor District, Indonesia. Biodiversitas 22: 2656-2666. Exploring novel wild-type microbes is very important to give more flexibility for bioremediation implementation. It is related to discovering strain with higher detoxification ability and more reliable degradation mechanisms. Moreover, novel strain can be used as genetic material for strain development by molecular genetic engineering and production design formulation. The aims of this experiment were to characterize and identify new mercury-resistant microbes, investigate their capacity to accumulate mercury, and analyze the reducing mercury toxicity in bioassay. Four strains of bacteria selected through the screening stage were characterized for their morphological, biochemical, physiological, and molecular genetic characteristics. Considering their characteristics and mercury resistance levels, there are two selected microbial strains: fungus strain Cladosporium halotolerans Hg32 and the bacterial strain Mycolicibacterium peregrinum Hg37 with a mercury resistance level up to 3000 mg L-1. The C. halotolerans Hg32 could remove mercury with the highest potency up to 90.72% at a mercury concentration of 100 mg L-1, while  M. peregrinum Hg37 removes up to 77.10% at mercury concentrations of 10 mg L-1. Toxicity bioassay tests using fish confirmed that C. halotolerans Hg32 and M. peregrinum Hg37 had the ability to detoxify mercury in contaminated water. Both have successfully proven to reduce the mortality rate to below 5%.

Invertase Diversity, Novel Strain and Production Technology DevelopmentInvertase or β-fructofuranosidase (E.C.3.2.1.2.6) have been a valuable enzyme in food industry, so that research about enhancing invertase activity on an industrial scale has been reported massively. So far, the production of the invertase enzyme is highly dependent on the potential activity of the invertase enzyme derived from microorganisms. The development of enzyme production technology is also a concern in invertase research to obtain an efficient and inexpensive production system. So far, various developments in enzyme production technology and enzyme utilization have been carried out, including various innovations in immobilizing and increasing the stabilization of the invertase enzyme during the production process. The development of superior strains and enzyme production technology continues amid the discovery of the latest approaches such as genetic engineering, protein modification, and nanotechnology. This paper aims to discuss invertase variation from various organisms, its correlation to novel microbial strain development to increase invertase production and invertase enzyme production technologies development including immobilization technology and stabilization of invertase enzymes.Keywords: β-fructofuranosidase, ezyme production, fermentation, immobilitation, invertase geneABSTRAKInvertase atau β-fructofuranosidase (E.C.3.2.1.2.6) merupakan enzim yang sangat penting dalam dunia industri pangan sehingga berbagai optimasi aktivitas enzim untuk produksi dalam skala industri terus dilakukan. Produksi enzim invertase hingga sejauh ini sangat bergantung oleh potensi aktivitas enzim invertase yang diambil dari mikroorganisme. Selain itu, pengembangan teknologi produksi juga menjadi perhatian dalam pengembangan produksi dan pemanfaatan enzim untuk mendapatkan sistem produksi yang efisien dan murah. Sejauh ini berbagai pengembangan teknologi produksi enzim dan pemanfaatan enzim telah dilakukan, diantaranya dengan berbagai inovasi dalam melakukan imobilisasi dan peningkatan stabilisasi enzim invertase selama proses produksi. Pengembangan strain unggul dan teknologi produksi enzim terus dilakukan di tengah ditemukannya pendekatan-pendekatan terkini seperti rekayasa genentika, modifikasi protein, dan teknologi nano. Artikel ini bertujuan untuk membahas variasi enzim invertase dari berbagai organisme, korelasi pengembangan strain mikrobia unggul terhadap peningkatan produksi enzim invertase, dan perkembangan teknologi produksi enzim invertase meliputi teknologi imobilisasi dan stabilisasi enzim invertase.

<p>Usaha pengendalian hama ulat grayak (Spodoptera litura) di tingkat petani masih mengandalkan pestisida sintetik. Tujuan penelitian adalah mengeksplorasi bakteri potensial pengendali hama ulat grayak (S. litura) dan menguji ketahanan bakteri potensial pada bahan pembawa kompos dan zeolit. Isolat tanah diisolasi dari tiga jenis sumber, yaitu sampel tanah daerah rhizosfer (padi, kelapa sawit, terung, jagung), sampel buah busuk (kakao, kelapa sawit, jambu air), dan sampel bangkai serangga (ulat api, belalang, kumbang tahi, kupu-kupu) yang diambil dari kawasan Dramaga dengan metode purposive sampling. Penelitian di laboratorium meliputi isolasi bakteri, uji patogenitas, pewarnaan gram, pengamatan morfologi koloni, uji toksisitas, uji biokimia, dan uji bahan pembawa. Berdasarkan penelitian ini didapatkan dua strain yang berpotensi sebagai agens biokontrol dengan kemampuan membunuh hama yang tinggi pada pengujian toksisitas tahap kedua, yaitu IRJ 10 (tingkat kematian 90%) dan ISU 4 (tingkat kematian 100%). Kedua isolat ini merupakan anggota genus Bacillus. Pada uji bahan pembawa kompos dan zeolit, penurunan jumlah sel bakteri pengendali hama paling tinggi adalah pada bahan pembawa zeolit dibandingkan dengan menggunakan bahan pembawa kompos. Jumlah sel bakteri pengendali hama pada masa penyimpanan 3 minggu masih di atas 108 CFU/g.</p><p><strong>Keywords</strong></p><p>Bakteri; Bahan pembawa; Ekplorasi; Agens pengendali hama; Ulat grayak (Spodoptera litura)</p><p><strong>Abstract</strong></p><p>The effort to control the Spodoptera litura at the farm level still used synthetic pesticides. This research aimed to explore potential bacteria as biological control of S. litura and do viability test of potential bacteria on compost and zeolite carrier. Soil potential bacteria had been isolated from three sources, including rhizosphere soil samples (rice, oil palm, eggplant, corn), rotten fruit samples (cocoa, oil palm, water), and insect samples (fireworms, locusts, dung beetles, butterflies) taken from Dramaga area with the purposive sampling method. Stages of laboratory study include isolation of bacterial isolates, pathogenicity tests, gram staining, colony morphology observation, toxicity test, biochemical test, and viability test. Two strains that have potential as biocontrol agents with a high ability to kill pests in the second stage of toxicity testing are IRJ 10 (90% mortality rate) and ISU 4 (100% mortality rate). Both of these isolates are members of the genus Bacillus. The highest number of viability was found in zeolite carriers. The number of bacterial cells in the three-week storage period is still above 108 CFU/g.</p>

Sustainable forage production is needed to meet animal feed needs as the livestock industry increases. The purpose of this study is to evaluate the effect of liquid and solid carrier material on the effectiveness and infectivity of Bradyrhizobium sp. strain PZS_A08 on the growth of Indigofera zollingeriana (I. zollingeriana). The two carrier materials used were zeolite (solid) and molasses (liquid). This study used two carrier materials consisting of zeolite (solid) and molasses (liquid). The five treatments given were P0 (50% NPK), P1 (50% NPK+liquid biofertilizer), P2 (50% NPK+sterile liquid biofertilizer), P3 (50% NPK+solid biofertilizer), P4 (50 % NPK+sterile solid biofertilizer), P5 (100% NPK). Observations were made on the plant's height, number of leaves, number of nodules, upperparts and root wet biomass, root and upper parts dry biomass, root length, and microbial population). The use of liquid and solid carrier materials effectively affected the effectiveness and infectivity of Bradyrhizobium sp. strain PZS_A08 on  I. zollingeriana. Inoculants Bradyrhizobium sp. strain PZS_A08 significantly increased plants' growth and reduced the use of 50% NPK fertilizer. Cold storage temperature (5ºC) effectively maintained Bradyrhizobium sp. strain PZS_A08 on liquid and solid carriers, while solid carriers showed better effectiveness at room temperature storage (30oC). Through this research, solid carriers such as zeolite are recommended as carriers for Bradyrhizobium sp. filter PZS_A08.