Judul: Potensi Bakteri Endofit Lamun Thalassia hemprichii Sebagai Penghasil Senyawa Antibakteri dari Perairan Pulau Pari, Kepulauan Seribu.
Abstrak: Bakteri endofit mampu menghasilkan senyawa bioaktif yang berpotensi dikembangkan dalam bidang farmasi, industri, dan pertanian. Penelitian ini bertujuan mengetahui adanya potensi antibakteri yang terdapat pada isolat bakteri endofit lamun Thalassia hemprichii. Bakteri endofit diisolasi menggunakan media ZoBell 2216E, didapatkan 31 isolat bakteri endofit dan dipilih 12 isolat untuk diuji antibakteri. Uji antibakteri dilakukan dengan metode difusi agar terhadap bakteri Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, Escherichia coli, dan Vibrio parahaemolyticus. Hasil uji antibakteri didapatkan 2 isolat yang dapat menghambat semua bakteri target, serta 3 isolat yang tidak mempunyai kemampuan menghambat terhadap semua bakteri target. Keterkaitan aktivitas antibakteri dengan kondisi lingkungan dan bakteri target uji diamati menggunakan analisis koresponden dan uji ANOVA (Analysis of Variance) menunjukkan hasil bahwa lokasi pengambilan sampel berpengaruh nyata terhadap aktivitas antibakteri.
Keyword: antibakteri, bakteri endofit, lamun, Thalassia hemprichii

Judul: Antibacterial Activity of Endophytic Bacteria from Seagrass Thalassia hemprichii in Pramuka Island, Seribu Islands, DKI Jakarta
Abstrak: Bakteri yang bersimbiosis dengan lamun dapat menghasilkan senyawa seperti inangnya. Bakteri endofit lamun Thalassia hemprichii dapat menghasilkan senyawa yang dapat menghambat pertumbuhan bakteri patogen. Penelitian ini bertujuan untuk menguji aktivitas senyawa antibakteri yang dihasilkan oleh bakteri endofit lamun T. hemprichii. Isolasi bakteri endofit dilakukan dengan media Zobell. Isolat yang berhasil diisolasi tersebut kemudian diuji aktivitas antagonisnya terhadap bakteri target (pembentuk biofilm) dan bakteri patogen Escherechia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis dengan metode overlay menggunakan media Zobell dan media Tryptic Soy Agar. Hasil uji antagonis dari 50 isolat yang diuji, terdapat 3 isolat Th1EE1, Th1E2 dan Th2EE2 yang mampu menghambat bakteri pembentuk biofilm. Ketiga isolat tersebut menunjukkan daya hambat dengan rentang 10,37 ± 0,16 mm sampai 15,685 ± 0,74 mm. Ketiga bakteri tersebut diuji terhadap bakteri patogen dan menunjukkan hasil positif dari Th1EE1 dan Th2EE2 terhadap bakteri patogen P. aeruginosa dan S. aureus. Observasi pertumbuhan dari ketiga isolat tersebut memiliki waktu stasioner berbeda, mulai dari 15 jam hingga 55 jam. Hasil ekstraksi yang dilakukan pada waktu stasioner dengan pelarut etil asetat dan etanol tidak menunjukkan adanya aktivitas antibakteri. Ketiadaan aktivitas ekstrak menunjukkan bahwa aktivitas antibakteri terjadi jika ada tekanan lingkungan (kompetisi)., Seagrass symbiotic bacteria can produce compounds similar to their host. Thalassia hemprichii endophytic bacteria can produce compounds that inhibit the proliferation of pathogenic bacteria. This study seeks to evaluate the antibacterial activity of compounds produced by endophytic bacteria in T. hemprichii seagrass. Bacteria are isolated using Zobell media. Successfully isolated isolates were then evaluated for antagonistic activity against target bacteria (biofilm formers) and pathogenic bacteria Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis using the overlay method on Zobell media and Tryptic Soy Agar media. Based on the results of the antagonist test, three of the fifty tested isolates are capable of inhibiting biofilm-forming bacteria: Th1EE1, Th1E2, and Th2EE2. The range of inhibition for the three isolates was 10.37 0.16 mm to 15.685 0.74 mm. Th1EE1 and Th2EE2 showed positive results against the pathogenic bacteria P. aeruginosa and S. aureus when tested against pathogenic bacteria. The stationary periods for the growth curves of the three isolates range from 15 to 55 hours. The results of stationary extractions with ethyl acetate and ethanol solvents revealed no antibacterial activity. The absence of extract activity suggests that antibacterial activity only occurs when environmental pressure (competition) is present.
Keyword: aktivitas antagonis, bakteri endofit, ekstrak, Thalassia hemprichii

Judul: Design of gathering-conveying unit of mobile sugar cane trash chopping machine
Abstrak: A machine for gathering and chopping the piles of sugarcane trash on the field after harvesting is being designed. As a part of the machine, a gathering-conveying unit was designed. Important data including condition and characteristics of trash were collected and used for designing the unit. The average bulk density of trash on the field was 7.7 kg/m3, the average pressure to compress the trash from 40 cm to 30 cm thickness was 50.65 N/m2, and the pressure to compress the trash from 27 cm to 8 cm thickness was 1166.60 N/m2. The unit was designed to be operated at 0.3 m/s forward speed, and having 60 cm working width. The unit was consisted of: a gathering reel, a pair of conveyors, cover-frame and power transmission components. Size and operational speed of moving components were determined by analyzing mass flow rate of the trash, and operating power of the components. The gathering reel was 100 cm in diameter and having 4 series of gathering fingers for drawing and feeding the trash into the conveyors. A pair of chain-conveyors equipped with L-shaped steel bars was set face to face on lower side and upper side for conveying and feeding the leaves to the chopping unit. The stationary test showed that the gathering reel and the conveyors could work properly. The average rotational speed of the conveyor shaft and the gathering reel were 34.03 rpm and 9.97 rpm, respectively. The working capacity of the unit was 400-500 kg/hour.
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