Highlights Bruguiera cylindrica is a mangrove plant in North Sumatra with limited information on its microbial endophytes. An enzyme bioprospection study was conducted revealing Vibrio alginolyticus as a prominent proteolytic strain. Vibrio alginolyticus Jme3-20 produced a multitude of extracellular enzymes such as amylase, cellulase, chitinase, phosphatase, and urease. This is the first report on finding Vibrio alginolyticus from mangrove area of North Sumatra.

Abstract. Rambey R, Susilowati A, Rangkuti AB, Onrizal O, Desrita, Ardhi R, Hartanto A. 2021. Plant diversity, structure and composition of vegetation around Barumun Watershed, North Sumatra, Indonesia. Biodiversitas 22: 3250-3256. Watershed ecosystem plays an important role in water and soil conservation which is supported by vegetation around watershed. As such, vegetation analysis is beneficial to assess the current state of watershed vegetation and monitor future changes. Barumun Watershed, located in South Labuhanbatu District, North Sumatra Province, Indonesia, is under threat due to habitat degradation and land conversion for plantation and agriculture. This research aimed to investigate the diversity, structure and composition of vegetation in the Barumun River including its smaller streams (rivulets). Data were collected using a combination of line transect and quadratic plots arranged systematically. The total observation plots were 48 plots, consisting of 24 plots in Barumun River, 12 plots in Tasik Rivulet and 12 plots in Titi Kembar Rivulet. The results documented a total of 51 plants in the studied sites in Barumun Watershed in which 37 species were found in Barumun River, 20 species in Tasik Rivulet and 17 species in the Titi Kembar Rivulet. Plant species consisted of several habitus including herbs, palms, shrubs, climbers and trees. The trees consisted of 22 species (43.13%), herbs 22 species (43.13%), climbers 3 species (5.88%), shrubs two species (3.92%), and palm two species (3.92%). The highest Importance Value Index (IVI) for tree community was recorded in the Barumun River from Hevea brasiliensis (108.28), followed by Cryptocarya sp. (123.24) in the Titi Kembar Rivulet. In addition, the highest IVI for pole, sapling, seedling, and shrub was recorded from Muntingia calabura (Barumun River), Nauclea orientalis (Tasik Rivulet), Psychotria viridiflora (Tasik Rivulet), and Calamus axillaris (Titi Kembar Rivulet), respectively. The plant diversity in Barumun Watershed was categorized from low to moderate level of richness.

The present study investigated diurnal or daily activity patterns of an individual captive lion (Panthera leo) in Siantar Zoo, North Sumatra, Indonesia. Behavioral observations of 70 hours in 10-days observation were analyzed descriptively for common Felidae behaviors identified using a standardized Felidae ethogram. The methodology used was focal animal sampling with continuous sampling of data record or 5-minute sampling periods. We reported that the captive lion allocated the most time budgets in inactive behavior or sleeping with the percentage of 62.88% or 2,604 minutes. Incidence of pacing as stereotypic behavior was documented in low percentage or 4.46% within the duration of or 189 minutes in our study. The dominant sleeping behavior may be considered as normal to captive Felidae in many zoos while some consideration upon their effect to visitor may be evaluated in the future study. Dynamic condition of display cage may be enriched to trigger better behavior related to welfare implications on the captive lion.

Ki rinyuh (Chromolaena odorata) is one of invasive plants species in Indonesia with potency as traditional medicine. The purpose of this study was to verify the presence of endophytic bacteria symbionts with Chromolaena odorata, and to evaluate the plant-growth promoting properties of endophytic bacteria in producing IAA, producing hydrolytic enzymes (α-amylase, β-amylase, cellulase, chitinase, protease) solubilizing phosphate. Isolation of endophytic bacteria was carried out by surface sterilizing the samples of roots, stems, leaves with 70% alcohol and 2% sodium hypochlorite, followed by direct plating of organ parts (1-2 cm) on top of Trypticase Soy Agar (TSA) medium. Bacterial isolates were differentiated through morphological biochemical characterization. A total of 19 endophytic bacteria were successfully recovered from Chromolaena odorata roots, stems and leaves. Four isolates produced the highest IAA, namely BECA1 (109 ± 0.98 ppm), BECA5 (104.13 ± 0.32 ppm), BECA8 (104.13 ± 0.71 ppm) and BECB3 (83.29 ± 0.47 ppm). Three isolates exhibit the highest phosphate solubilization (+++) namely BECA5, BECA1, BECA8 after 4 days of incubation. Furthermore, BECB3 produced a considerable hydrolytic enzyme activities: β-amylase (+++), α-amylase (++), cellulase (+++), chitinase (++) and protease (+++) compared to other isolates. Our result may provide an insight upon the beneficial interaction by plant-growth promoting endophytic bacteria to support the invasiveness of the plant.

Hydrocarbon contamination in soil and water is still a major concern and considered as a serious environmental issue to various natural habitats. Microbial degradation of hydrocarbon compounds is considered as one of eco-friendly method to overcome this issue of contamination. Toulene-degrading bacteria were successfully recovered from contaminated marine seawater of Belawan and Tanjung Balai, North Sumatera. Three bacterial isolates identified as Pseudomonas aeruginosa TJB01, Pseudomonas sp. TJB05, and Acinetobacter sp. SBG05 were subjected to degradation test by evaluating their hydrocarbon-degrading activities towards Toluene as one of selected hydrocarbon compounds of BTEX. Parameters observed in this study were bacterial cell density (Colony-forming unit/mL) by using Total Plate Count method and hydrocarbon residues (ppm) quantified by using Gas Chromatography. Initial concentration of Toluene was detected 173.10 ppm. Isolate P. aeruginosa TJB01 produced the highest cell density (log 7.94 CFU.mL−1) and produced the highest toluence degradation (%) at 59.46% than other isolates and bacterial consortium during 12 days of incubation period. Further investigations are needed to optimize consortium potential in exhibiting better degradation activities.