Try this:

Spirillum Nitrogen-Fixing Medium

Composition per liter:

Sodium malate .............................................................................. 5.0g

KH2PO4......................................................................................... 0.4g

MgSO4·7H2O................................................................................ 0.2g

K2HPO4......................................................................................... 0.1g

NaCl .............................................................................................. 0.1g

Yeast extract................................................................................ 0.05g

CaCl2........................................................................................... 0.02g

FeCl3 ........................................................................................... 0.01g

NaMoO4·2H2O........................................................................... 2.0mg

pH 7.2-7.4 ± 0.2 at 25°C

Preparation of Medium: Add components to distilled/deionized

water and bring volume to 1.0L. Mix thoroughly. Distribute into tubes

or flasks. Autoclave for 15 min at 15 psi pressure–121°C.

Use: For the cultivation and maintenance of Azospirillum brasilense,

Azospirillum lipoferum, and Herbaspirillum seropedicae.

I would recommend using plant-based culture media, it recovers wide range of endophytic genera. It is very simple and cheap to prepare. 

Have a look on the attachments 

Article Plant powder teabags: A novel and practical approach to reso...

Article Plant-fed versus chemicals-fed rhizobacteria of Lucerne: Pla...

 Dear Jakub,

Thanks a lot.I will try.

 Dear Sarhan,

Thank you.It is useful for me.

Vasvi,

We just isolate on YES (agar with yeast extract (1%) and sucrose (1%)) or a comparable medium then culture on Norris nitrogen free to screen for possible N fixers. The real trick is to get them out of the plant. Many are really hard to culture directly from the plant. Once you get them into culture they grow fine.

Dear James F White,

Thanks a lot.

I 've used N-free medium

Hi Md

Several helpful references on attachment 1

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0ahUKEwjz2PLk2JnWAhWMchQKHeX9CToQFggwMAI&url=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC3769033%2F&usg=AFQjCNFvMeIX299AqysPgw9AERHuBd3N0Q

2

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8&ved=0ahUKEwjz2PLk2JnWAhWMchQKHeX9CToQFgg4MAM&url=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC4476825%2F&usg=AFQjCNGJP2JpznGW7QS2pRdtx-E33k-BMg

2

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ved=0ahUKEwjz2PLk2JnWAhWMchQKHeX9CToQFgg_MAQ&url=https%3A%2F%2Fwww.jstor.org%2Fstable%2F42952920&usg=AFQjCNGahwUqQckjb3m8J1xhNwefPpPcnQ

3

https://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652005000300014

4

https://www.fnca.mext.go.jp/bf/bfm/pdf/4_2_Non-Symbiotic_Nitrogen_Fixers0404.pdf

5

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&cad=rja&uact=8&ved=0ahUKEwjz2PLk2JnWAhWMchQKHeX9CToQFghSMAc&url=http%3A%2F%2Fwww.icb.usp.br%2Fbmm%2Fhrbarbos%2Farquivos%2Fjournal_of_applied_microbiology_101_2006.pdf&usg=AFQjCNEI9y1QdOTwOrS_iFekVgKZM-MWpA

6

https://www.cabi.org/gara/FullTextPDF/2009/20093019323.pdf

7

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&cad=rja&uact=8&ved=0ahUKEwjz2PLk2JnWAhWMchQKHeX9CToQFghkMAk&url=http%3A%2F%2Fijs.microbiologyresearch.org%2Fcontent%2Fjournal%2Fijsem%2F10.1099%2F00207713-51-1-157%3Fcrawler%3Dtrue%26mimetype%3Dapplication%2Fpdf&usg=AFQjCNGV3v-Psoidm3-cNUr363dPLeWNgQ

8

https://www.hindawi.com/journals/ija/2014/208383/

9

https://scienceasia.org/2007.33.n4/v33_429_435.pdf

10

https://www.sciencedirect.com/science/article/pii/S209012321500079X

11

https://widyariset.pusbindiklat.lipi.go.id/index.php/widyariset/article/view/570

12

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=16&cad=rja&uact=8&ved=0ahUKEwj1yJbd2ZnWAhULvxQKHfWhBRo4ChAWCEYwBQ&url=https%3A%2F%2Fbiotechnologyforbiofuels.biomedcentral.com%2Farticles%2F10.1186%2Fs13068-015-0404-y&usg=AFQjCNFSVZe3LkhnSAzFlWNNnWQnR3Nqdg

13

https://jb.asm.org/content/183/8/2634.full

14

https://www.jstage.jst.go.jp/article/jsme2/22/3/22_3_197/_pdf

15

https://jabonline.in/admin/php/uploads/28_pdf.pdf

16

https://www.imok.ufl.edu/hlb/database/pdf/00002863.pdf

17

https://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-95162014000200019

18

https://amb-express.springeropen.com/articles/10.1186/s13568-014-0026-y

19

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=23&cad=rja&uact=8&ved=0ahUKEwiCqcGh2pnWAhXIwxQKHYT_DWE4FBAWCDQwAg&url=https%3A%2F%2Fwww120.secure.griffith.edu.au%2Frch%2Ffile%2F40adc91d-afa5-8e84-41ce-7ae8b5ef6c41%2F1%2F03Chapter2.pdf&usg=AFQjCNEdiVahxm6T0_YZz_hbz3xJfAc5RA