Removal of contamination based on a negative control occurs when all of "P = NA"

[1023011930]

metadata.csv pivot_data.csv Thank you very much for your great contribution to data cleansing! The abundance table I used was the TPM abundance of different contigs The code I use is：

setwd("mydata/") cran_packages <- c("reshape2", "ggplot2", "vegan", "stringr", "gridExtra", "ape", "RColorBrewer", "dplyr", "knitr","cowplot","openxlsx", "circlize", "plotly") bioc_packages <- c("phyloseq","decontam","ComplexHeatmap") sapply(c(cran_packages, bioc_packages), require, character.only = TRUE)

otu <- read.csv("pivot_data.csv", row.names = 1, check.names = F) mapp <- read.csv("metadata.csv", row.names = 1) otu <- otu_table(as.matrix(otu), taxa_are_rows = T) mapp <- sample_data(mapp) ps <- phyloseq(otu, mapp) head(sample_data(ps))

df <- as.data.frame(sample_data(ps)) # Put sample_data into a ggplot-friendly data.frame df$LibrarySize <- sample_sums(ps) df <- df[order(df$LibrarySize),] df$Index <- seq(nrow(df)) ggplot(data=df, aes(x=Index, y=LibrarySize, color=Sample_or_Control)) + geom_point()

sample_data(ps)$is.neg <- sample_data(ps)$Sample_or_Control == "Control Sample" contamdf.prev <- isContaminant(ps, method="prevalence", neg="is.neg", threshold=0.5) table(contamdf.prev$contaminant)

FALSE 3257

head(which(contamdf.prev$contaminant))

integer(0)

And the result shown as this image I finded that all the “p.freq p.prev p” = NA My sincere question to you, is my metadata and abundance table not done properly, or is there something wrong with my code, or is my data really not contaminated? If you could answer this question for me, I would be very grateful!

[1023011930]

the PS data goes like this

[1023011930]

Also, my study is a low biomass study, does it need to be changed to isNotContaminant

[1023011930]

setwd("/") library(phyloseq) library(decontam)

mapp <- read.table("metadata.csv", sep=",", row.names=1, header=T, comment.char="") otu <- as.matrix(read.table("pivot_data.csv", sep=",", row.names=1, header=T, check.names=F))

otu <- otu_table(otu, taxa_are_rows=T) mapp <- sample_data(mapp) ps <- phyloseq(otu, mapp) head(sample_data(ps)) sample_data(ps)$is.neg <- sample_data(ps)$Sample_or_Control == "Control Sample" contamdf.notcontam <- isNotContaminant(ps, method="prevalence", neg="is.neg", threshold=0.5,detail=TRUE) write.table(contamdf.notcontam, file="contamdf_notcontam.txt", sep="\t", quote=F, row.names=T)

Is there any error in my isNotContaminant code? Because the export is also wrong

[benjjneb]

You are using contig-level data here. Are the contigs defined separately for each sample?

[1023011930]

M10 is one of my samples, I used contigs.fa assembled by M10 as index for decontamination test. Then, I used bwa-mem2 to mapping the clean_data of 64 samples (including four NC samples) back to contigs.fa, and calculated the TPM using samtools and my own python code. Finally, I got "pivot_data.csv"

[1023011930]

Thank you very much for the help you can give me, it will be very helpful!

[benjjneb]

In the feature table you are working with, are there every any features observed in more than one sample? Or is every feature specific to a sample?

otu <- as.matrix(read.table("pivot_data.csv", sep=",", row.names=1, header=T, check.names=F))
table(rowSums(otu>0))
table(colSums(otu>0))

[1023011930]

[1023011930]

I think, every feature specific to a Sample(M10). Because in this test, the TPM is counted by the contig.fa assembled by M10_clean_data.fq

[1023011930]

Or you mean the present times of each contig_name in the CSV table?

[benjjneb]

Your table(colSums(otu>0)) results yield mostly 1s, and a few 2s.

Let's nail this down: Does that mean that your features (contigs) are only being observed as present in 1 or 2 samples?

[1023011930]

Your answer made me think. 这是我输入的csv文件，可以看到“M10_1001_510”在各个样品中的TPM都不为零。 Also, for each column, my data is barely zero. So "table(colSums(otu>0))" results in mostly 1's, and I don't know why, is there something wrong with the way I'm importing the data?

[1023011930]

Thank you very much for the help you can give me, it will be very helpful!

[1023011930]

In the "Introduction to decontam" the import data is [eadRDS(system.file("extdata", "MUClite.rds", package="decontam"))], RDS data, so i am a little confuse about how to import no-RDS data or PS data

[1023011930]

After your reminder, I redid the data import metadata.csv pivot_datawen.csv setwd("") library(phyloseq) library(decontam)

otu_matrix <- read.csv("pivot_datawen.csv", row.names = 1) sample_data <- read.csv("metadata.csv", row.names = 1)

otu_table <- otu_table(otu_matrix, taxa_are_rows = TRUE) sample_data <- sample_data(sample_data) physeq <- phyloseq(otu_table, sample_data) saveRDS(physeq, "physeq.rds") ps <- readRDS("physeq.rds")

sample_data(ps)$is.neg <- sample_data(ps)$Sample_or_Control == "Control Sample" contamdf.notcontam <- isNotContaminant(ps, method="prevalence", neg="is.neg", threshold=0.5,detail=TRUE) write.table(contamdf.notcontam, file="contamdf_notcontam.txt", sep="\t", quote=F, row.names=T)

However，P also = NA in all contigs

[1023011930]

Finally I find the bug, and we should change it to "Control" I this test, Is "not.contaminant:FALSE" means this contig is a contamination? Thanks again for taking the time to mentor me！！！