Introduction　In　recent　years,　researchers　have　been　exploring　the　plastic-degrading　abilities　of　bacteria　residing　in　the　guts　of　Styrofoam-eating　Tenebrio　molitor　larvae.　However,　none　of　the　reported　strains　have　displayed　highly　efficient　plastic　degradation　capabilities,　and　it＇s　noteworthy　that　none　of　the　existing　studies　have　focused　on　strictly　anaerobic　microbes.Methods　In　this　study,　we　exclusively　fed　Styrofoam　to　T.　molitor　larvae　and　examined　how　this　dietary　change　influence　the　gut＇s　bacterial　community　composition,　as　observed　through　fecal　bacteria　using　bacterial　16S　rRNA　gene　amplicon　sequencing　and　the　small-scale　culturomics　method　with　20　types　of　anaerobic　media　under　four　different　conditions.Results　The　results　revealed　a　significant　shift　in　the　dominant　phylogroup　from　Lactococcus　(37.8%)　to　Escherichia-Shigella　(54.7%)　when　comparing　the　feces　of　larvae　fed　with　bran　and　Styrofoam,　as　analyzing　through　the　bacterial　16S　rRNA　gene　amplicon　sequencing.　For　small-scale　culturomics　method,　a　total　of　226　strains　of　anaerobic　bacteria　were　isolated　and　purified　using　the　rolling-tube/strictly　anaerobic　technique.　Among　them,　226　strains　were　classified　into　3　phyla,　7　classes,　9　orders,　17　families,　29　genera,　42　known　species　and　34　potential　novel　species.Discussion　Interestingly,　24　genera　in　total,　identified　through　the　culturomics　method,　were　not　found　in　the　results　obtained　from　amplicon　sequencing.　Here,　we　present　a　collection　of　culturable　anaerobic　bacteria　from　the　feces　of　T.　molitor　larvae,　which　might　be　a　promising　avenue　for　investigating　the　biodegradability　of　plastics　by　combining　specific　strains,　either　randomly　or　intentionally,　while　considering　the　abundance　ratio　of　the　microbial　community　composition.