Jamur tiram putih Pleurotus ostreatus merupakan salah satu jenis jamur yang paling banyak dibudidayakan di dunia. Nutrien yang tersedia di dalam media tanam merupakan faktor yang mempengaruhi terhadap pertumbuhan jamur. Penelitian bertujuan untuk mengisolasi bakteri pemicu pertumbuhan jamur dan meneliti pengaruhnya dalam pertumbuhan miselia jamur dan mempelajari pengaruhnya terhadap pertumbuhan tubuh buah jamur pada konsentrasi berbeda 50 dan 75 . Sembilan belas bakteri diisolasi dari media tanam jamur tiram putih dan diamati pengaruhnya terhadap pertumbuhan miselia jamur tiram putih. Tiga isolat bakteri dengan hasil pertumbuhan miselia terbaik kemudian diidentifikasi berdasarkan sekuensing 16S rRNA dan konstruksi pohon filogenetik dilakukan dengan metode neighbor-joining menggunakan aplikasi MEGA versi 6.06 dengan 1000x bootstraps. Berdasarkan pertumbuhan miselia pada media PDA, terlihat bahwa terdapat perbedaan antar perlakuan dalam jumlah hari yang dibutuhkan bagi miselia untuk tumbuh memenuhi cawan petri 3 hari lebih cepat dibanding kontrol dan diidentifikasi sebagai Bacillus cereus strain ATCC 14579, Bacillus aryabhattai strain B8W22 dan Acinetobacter pittii strain ATCC 19004. Terjadi peningkatan kecepatan tumbuh miselia, jumlah tubuh buah, panjang tangkai, dan berat basah tubuh buah jamur tiram putih terhadap penambahan ekstrak B. aryabhattai pada media tanam. Hasil dari penelitian ini menunjukkan bahwa penambahan ekstrak isolat bakteri memiliki efek menguntungkan bagi pertumbuhan jamur.

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White oyster mushroom Pleurotus ostreatus is one of the most widely cultivated mushrooms in the world. Nutrients available in the growth medium are factors that affect the growth of fungi. The study aimed to isolate the bacteria that promote the growth of the mushroom and studied its effect in mycelial growth and studied its effect on the growth of mushroom fruit body at different concentrations 50 and 75 . Nineteen bacteria were isolated from the white oyster mushroom growth media and its effect on the growth of mycelia of white oyster mushrooms was observed. Three isolates of bacteria with the best results on mycelia growth then identified based on 16S rRNA sequencing and phylogenetic tree construction performed by neighbor joining method using MEGA version 6.06 application with 1000x bootstraps.

Based on mycelial growth on PDA media, it was seen that there was a difference between treatments in the number of days required for mycelia to grow to fill the petri dish 3 days earlier than control and identified as Bacillus cereus strain ATCC 14579, Bacillus aryabhattai strain B8W22 and Acinetobacter pittii strain ATCC 19004. There is an increase in the growth rate of mycelia, the number of fruit body, the length of the stalk, and the fresh weight of the fruit body of white oyster mushroom by the addition of B. aryabhattai extract on growth medium. The results of this study indicate that the addition of bacterial isolate extracts has a beneficial effect on the mushroom growth.