**Waleed Asghar, Shiho Kondo, Riho Iguchi, Ahmad Mahmood and Ryota Kataoka \***

Department of Environmental Sciences, Faculty of Life and Environmental Sciences, University of Yamanashi, Kofu, Yamanashi 400-8510, Japan; waleedasghar978@gmail.com (W.A.); g19lr004@yamanashi.ac.jp (S.K.); lustiness\_17@yahoo.co.jp (R.I.); ahmadmahmood91@gmail.com (A.M.)

**\*** Correspondence: rkataoka@yamanashi.ac.jp

Received: 15 June 2020; Accepted: 30 June 2020; Published: 2 July 2020

**Abstract:** Organic amendment is important for promoting soil quality through increasing soil fertility and soil microbes. This study evaluated the effectiveness of using liquid food waste material (LFM) as a microbial resource, by analyzing the microbial community composition in LFM, and by isolating plant growth-promoting bacteria (PGPB) from the material. High-throughput sequencing of LFM, collected every month from May to September 2018, resulted in the detection of >1000 bacterial operational taxonomic units (OTUs) in the LFM. The results showed that *Firmicutes* was abundant and most frequently detected, followed by *Proteobacteria* and *Actinobacteria.* Of the culturable strains isolated from LFM, almost all belonged to the genus *Bacillus*. Four strains of PGPB were selected from the isolated strains, with traits such as indole acetic acid production and 1-aminocyclopropane-1-carboxylic acid deaminase activity. Lettuce growth was improved via LFM amendment with PGPB, and *Brassica rapa* showed significant differences in root biomass when LFM amendment was compared with the use chemical fertilizer. Field experiments using LFM showed slight differences in growth for *Brassica rapa,* lettuce and eggplant, when compared with the use of chemical fertilizer. LFM is a useful microbial resource for the isolation of PGPB, and its use as fertilizer could result in reduced chemical fertilizer usage in sustainable agriculture.

**Keywords:** bacterial community composition; liquid food waste materials (LFM); plant growth-promoting bacteria (PGPB); plant growth-promoting (PGP) traits
