diff --git a/DESCRIPTION b/DESCRIPTION
index 3bc3d08..7b29a36 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,6 +1,6 @@
 Package: MsIO
 Title: Serializing and restoring/importing mass spectrometry data objects
-Version: 0.0.6
+Version: 0.0.7
 Authors@R:
     c(person(given = "Johannes", family = "Rainer",
              email = "Johannes.Rainer@eurac.edu",
@@ -45,7 +45,8 @@ Suggests:
     xcms,
     alabaster.se,
     alabaster.matrix,
-    MsBackendMetaboLights,
+    MsBackendMetaboLights (>= 0.99.1),
+    BiocFileCache,
     QFeatures
 License: Artistic-2.0
 Encoding: UTF-8
@@ -61,6 +62,7 @@ Collate:
     'AllGenerics.R'
     'MetaboLightsParam.R'
     'MsBackend.R'
+    'MsBackendMetaboLights.R'
     'MsBackendMzR.R'
     'MsExperiment.R'
     'MsExperimentFiles.R'
diff --git a/NAMESPACE b/NAMESPACE
index c628a80..e9b5e09 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -26,6 +26,7 @@ importFrom(jsonlite,read_json)
 importFrom(jsonlite,serializeJSON)
 importFrom(jsonlite,unserializeJSON)
 importFrom(jsonlite,write_json)
+importFrom(methods,"slot<-")
 importFrom(methods,as)
 importFrom(methods,callNextMethod)
 importFrom(methods,existsMethod)
diff --git a/NEWS.md b/NEWS.md
index b0bda56..756be9d 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,9 @@
 # Version 0.0
 
+## Changes in 0.0.7
+
+- Add `saveObject()` for `MsBackendMetaboLights`.
+
 ## Changes in 0.0.6
 
 - Expand unit tests.
diff --git a/R/AlabasterParam.R b/R/AlabasterParam.R
index fcc67b4..864fe44 100644
--- a/R/AlabasterParam.R
+++ b/R/AlabasterParam.R
@@ -27,8 +27,15 @@
 #'
 #' - `MsBackendMzR`, defined in the
 #'   [*Spectra*](https://bioconductor.org/packages/Spectra) package.
+#' - `MsBackendMetaboLights`, defined in the
+#'   [*MsBackendMetaboLights*](https://github.com/RforMassSpectrometry/MsBackendMetaboLights)
+#'   package.
 #' - `Spectra`, defined in the
 #'   [*Spectra*](https://bioconductor.org/packages/Spectra) package.
+#' - `MsExperiment`, defined in the
+#'   [*MsExperiment*](https://bioconductor.org/packages/MsExperiment) package.
+#' - `XcmsExperiment`, defined in the
+#'   [*xcms*](https://bioconductor.org/packages/xcms) package.
 #'
 #' In addition, the *MsIO* package defines the `AlabasterParam` which can be
 #' used to write or read MS objects using the `saveMsObject()` and
@@ -55,11 +62,17 @@
 #'     listed below.
 #'
 #' @param spectraPath For `readMsObject()`: `character(1)` optionally allowing
-#'   to define the (absolute) path where the spectra files (*data storage
-#'   files*) can be found. This parameter is used for `MsBackendMzR` (see
-#'   descriptions below) and can be passed through `...` also to
-#'   `readMsObject()` functions for other classes (such as `Spectra`,
-#'   `MsExperiment` etc).
+#'     to define the (absolute) path where the spectra files (*data storage
+#'     files*) can be found. This parameter is used for `MsBackendMzR` (see
+#'     descriptions below) and can be passed through `...` also to
+#'     `readMsObject()` functions for other classes (such as `Spectra`,
+#'     `MsExperiment` etc).
+#'
+#' @param offline For `readMsObject()` and `readObject()` to load MS data as a
+#'     `MsBackendMetaboLights()`: `logical(1)` to evaluate the local file cache
+#'     and only load local files. Thus `offline = TRUE` does not need an active
+#'     internet connection, but fails if one of more files are not cached
+#'     locally.
 #'
 #' @param ... optional additional parameters passed to the downstream
 #'     functions, such as for example `spectraPath` described above.
@@ -73,6 +86,7 @@
 #'     first parameter, from the specified path. `saveObject()` and
 #'     `saveMsObject()` don't return anything.
 #'
+#'
 #' @section On-disk storage for `MsBackendMzR` objects:
 #'
 #' `MsBackendMzR` objects can be exported or imported using the
@@ -94,6 +108,15 @@
 #' below for details.
 #'
 #'
+#' @section On-disk storage for `MsBackendMetaboLights` objects:
+#'
+#' The `MsBackendMetaboLights` extends the `MsBackendMzR` backend and hence the
+#' same files are stored. When a `MsBackendMetaboLights` object is restored,
+#' the `mtbls_sync()` function is called to check for presence of all MS data
+#' files and, if missing, re-download them from the *MetaboLights* repository
+#' (if parameter `offline = FALSE` is used).
+#'
+#'
 #' @section On-disk storage for `Spectra` objects:
 #'
 #' `Spectra` objects can be exported/imported using `saveMsObject()` and
diff --git a/R/MsBackendMetaboLights.R b/R/MsBackendMetaboLights.R
new file mode 100644
index 0000000..e76fdb0
--- /dev/null
+++ b/R/MsBackendMetaboLights.R
@@ -0,0 +1,72 @@
+#' @rdname PlainTextParam
+setMethod("readMsObject", signature(object = "MsBackendMetaboLights",
+                                    param = "PlainTextParam"),
+          function(object, param, offline = FALSE) {
+              fl <- file.path(param@path, "ms_backend_data.txt")
+              if (!file.exists(fl))
+                  stop("No 'backend_data.txt' file found in the provided path.")
+              l2 <- readLines(fl, n = 2)
+              if (l2[1] != "# MsBackendMetaboLights")
+                  stop("Invalid class in 'ms_backend_data.txt' file.",
+                  "Should run with object = ", l2[1])
+              if (length(l2) > 1L) {
+                  data <- read.table(file = fl, sep = "\t", header = TRUE)
+                  rownames(data) <- NULL
+                  slot(object, "spectraData", check = FALSE) <- DataFrame(data)
+                  MsBackendMetaboLights::mtbls_sync(object, offline = offline)
+              }
+              validObject(object)
+              object
+          })
+
+################################################################################
+##
+## alabaster saveObject/readObject
+##
+################################################################################
+#' @rdname AlabasterParam
+setMethod("saveObject", "MsBackendMetaboLights", function(x, path, ...) {
+    .save_object_spectra_data(x, path, object = "ms_backend_metabo_lights")
+})
+
+#' @noRd
+#'
+#' @importFrom methods slot<-
+readAlabasterMsBackendMetaboLights <- function(path = character(),
+                                               metadata = list(),
+                                               offline = FALSE) {
+    if (!.is_spectra_installed())
+        stop("Required package 'Spectra' missing. Please install ",
+             "and try again.", call. = FALSE)
+    if (!.is_ms_backend_metabo_lights_installed())
+        stop("Required package 'MsBackendMetaboLights' missing. ",
+             "Please install and try again.", call. = FALSE)
+    validateAlabasterMsBackendMzR(path, metadata)
+    sdata <- altReadObject(file.path(path, "spectra_data"))
+    pvars <- altReadObject(file.path(path, "peaks_variables"))
+    be <- MsBackendMetaboLights::MsBackendMetaboLights()
+    slot(be, "spectraData", check = FALSE) <- sdata
+    slot(be, "peaksVariables", check = FALSE) <- pvars
+    MsBackendMetaboLights::mtbls_sync(be, offline = offline)
+    validObject(be)
+    be
+}
+
+#' @rdname AlabasterParam
+setMethod("saveMsObject", signature(object = "MsBackendMetaboLights",
+                                    param = "AlabasterParam"),
+          function(object, param) {
+              if (file.exists(param@path))
+                  stop("Overwriting or saving to an existing directory is not",
+                       " supported. Please remove the directory defined with",
+                       " parameter `path` first.")
+              saveObject(object, param@path)
+          })
+
+#' @rdname AlabasterParam
+setMethod("readMsObject", signature(object = "MsBackendMetaboLights",
+                                    param = "AlabasterParam"),
+          function(object, param, offline = FALSE) {
+              readAlabasterMsBackendMetaboLights(path = param@path,
+                                                 offline = offline)
+          })
diff --git a/R/MsBackendMzR.R b/R/MsBackendMzR.R
index 18702b8..9dd8732 100644
--- a/R/MsBackendMzR.R
+++ b/R/MsBackendMzR.R
@@ -88,9 +88,14 @@ setMethod("readMsObject", signature(object = "MsBackendMzR",
 #'
 #' @rdname AlabasterParam
 setMethod("saveObject", "MsBackendMzR", function(x, path, ...) {
+    .save_object_spectra_data(x, path, object = "ms_backend_mz_r")
+})
+
+.save_object_spectra_data <- function(x, path, object, version = "1.0") {
     dir.create(path = path, recursive = TRUE, showWarnings = FALSE)
-    saveObjectFile(path, "ms_backend_mz_r",
-                   list(ms_backend_mz_r =list(version = "1.0")))
+    l <- list(list(version = version))
+    names(l) <- object
+    saveObjectFile(path, object, l)
     tryCatch({
         do.call(altSaveObject,
                 list(x = x@spectraData, path = file.path(path, "spectra_data")))
@@ -104,9 +109,9 @@ setMethod("saveObject", "MsBackendMzR", function(x, path, ...) {
                      path = file.path(path, "peaks_variables")))
     }, error = function(e) {
         stop("failed to save 'peaksVariables' of ", class(x)[1L], "\n - ",
-             e$message)
+             e$message, call. = FALSE)
     })
-})
+}
 
 #' @importFrom alabaster.base registerValidateObjectFunction
 #'
diff --git a/R/PlainTextParam.R b/R/PlainTextParam.R
index a5d82d4..5dbeede 100644
--- a/R/PlainTextParam.R
+++ b/R/PlainTextParam.R
@@ -26,13 +26,16 @@
 #' are:
 #'
 #' - `MsBackendMzR` object, defined in the
-#'   ([Spectra](https://bioconductor.org/packages/Spectra)) package.
+#'   [*Spectra*](https://bioconductor.org/packages/Spectra) package.
+#' - `MsBackendMetaboLights` object, defined in the
+#'   [*MsBackendMetaboLights*](https://bioconductor.org/packages/MsBackendMetaboLights)
+#'   package.
 #' - `Spectra` object, defined in the
-#'   ([Spectra](https://bioconductor.org/packages/Spectra)) package.
+#'   [*Spectra*](https://bioconductor.org/packages/Spectra) package.
 #' - `MsExperiment` object, defined in the
-#'   ([MsExperiment](https://bioconductor.org/packages/MsExperiment)) package.
+#'   [*MsExperiment*](https://bioconductor.org/packages/MsExperiment) package.
 #' - `XcmsExperiment` object, defined in the
-#'   ([xcms](https://bioconductor.org/packages/xcms)) package.
+#'   [*xcms*](https://bioconductor.org/packages/xcms) package.
 #'
 #' See their respective section below for details and formats of the
 #' exported files.
@@ -48,6 +51,11 @@
 #'   `readMsObject()` functions for other classes (such as `Spectra`,
 #'   `MsExperiment` etc).
 #'
+#' @param offline For `readMsObject()` to load MS data as a
+#'   `MsBackendMetaboLights()`: `logical(1)` to evaluate **only** the local
+#'   file cache. Thus `offline = TRUE` does not need an active internet
+#'   connection, but fails if one of more files are not cached locally.
+#'
 #' @param ... Additional parameters passed down to internal functions. E.g.
 #'   parameter `spectraPath` (see above).
 #'
@@ -68,6 +76,15 @@
 #'   named *ms_backend_data.txt*. Each row of this tab-delimited text file
 #'   corresponds to a spectrum with its respective metadata in the columns.
 #'
+#'
+#' @section On-disk storage for `MsBackendMetaboLights` objects:
+#'
+#' The `MsBackendMetaboLights` extends the `MsBackendMzR` backend and hence the
+#' same files are stored. When a `MsBackendMetaboLights` object is restored,
+#' the `mtbls_sync()` function is called to check for presence of all MS data
+#' files and, if missing, re-download them from the *MetaboLights* repository.
+#'
+#'
 #' @section On-disk storage for `Spectra` objects:
 #'
 #' For `Spectra` objects, defined in the `Spectra` package, the files listed
diff --git a/R/zzz.R b/R/zzz.R
index 6e7bcda..b9b9b0d 100644
--- a/R/zzz.R
+++ b/R/zzz.R
@@ -3,6 +3,10 @@
     registerValidateObjectFunction("ms_backend_mz_r",
                                    validateAlabasterMsBackendMzR)
     registerReadObjectFunction("ms_backend_mz_r", readAlabasterMsBackendMzR)
+    registerValidateObjectFunction("ms_backend_metabo_lights",
+                                   validateAlabasterMsBackendMzR)
+    registerReadObjectFunction("ms_backend_metabo_lights",
+                               readAlabasterMsBackendMetaboLights)
     registerValidateObjectFunction("spectra", validateAlabasterSpectra)
     registerReadObjectFunction("spectra", readAlabasterSpectra)
     registerValidateObjectFunction("ms_experiment_files",
diff --git a/man/AlabasterParam.Rd b/man/AlabasterParam.Rd
index 5f7583e..c6c85d8 100644
--- a/man/AlabasterParam.Rd
+++ b/man/AlabasterParam.Rd
@@ -1,10 +1,13 @@
 % Generated by roxygen2: do not edit by hand
-% Please edit documentation in R/AlabasterParam.R, R/MsBackendMzR.R,
-%   R/MsExperiment.R, R/Spectra.R, R/XcmsExperiment.R
+% Please edit documentation in R/AlabasterParam.R, R/MsBackendMetaboLights.R,
+%   R/MsBackendMzR.R, R/MsExperiment.R, R/Spectra.R, R/XcmsExperiment.R
 \name{AlabasterParam}
 \alias{AlabasterParam}
 \alias{readObject}
 \alias{saveObject,MsExperimentFiles-method}
+\alias{saveObject,MsBackendMetaboLights-method}
+\alias{saveMsObject,MsBackendMetaboLights,AlabasterParam-method}
+\alias{readMsObject,MsBackendMetaboLights,AlabasterParam-method}
 \alias{saveObject,MsBackendMzR-method}
 \alias{saveMsObject,MsBackendMzR,AlabasterParam-method}
 \alias{readMsObject,MsBackendMzR,AlabasterParam-method}
@@ -21,6 +24,12 @@
 \usage{
 AlabasterParam(path = tempdir())
 
+\S4method{saveObject}{MsBackendMetaboLights}(x, path, ...)
+
+\S4method{saveMsObject}{MsBackendMetaboLights,AlabasterParam}(object, param)
+
+\S4method{readMsObject}{MsBackendMetaboLights,AlabasterParam}(object, param, offline = FALSE)
+
 \S4method{saveObject}{MsBackendMzR}(x, path, ...)
 
 \S4method{saveMsObject}{MsBackendMzR,AlabasterParam}(object, param)
@@ -64,6 +73,12 @@ functions, such as for example \code{spectraPath} described above.}
 and file name or directory to/from which the data object should be
 exported/imported.}
 
+\item{offline}{For \code{readMsObject()} and \code{readObject()} to load MS data as a
+\code{MsBackendMetaboLights()}: \code{logical(1)} to evaluate the local file cache
+and only load local files. Thus \code{offline = TRUE} does not need an active
+internet connection, but fails if one of more files are not cached
+locally.}
+
 \item{spectraPath}{For \code{readMsObject()}: \code{character(1)} optionally allowing
 to define the (absolute) path where the spectra files (\emph{data storage
 files}) can be found. This parameter is used for \code{MsBackendMzR} (see
@@ -95,8 +110,15 @@ these objects:
 \itemize{
 \item \code{MsBackendMzR}, defined in the
 \href{https://bioconductor.org/packages/Spectra}{\emph{Spectra}} package.
+\item \code{MsBackendMetaboLights}, defined in the
+\href{https://github.com/RforMassSpectrometry/MsBackendMetaboLights}{\emph{MsBackendMetaboLights}}
+package.
 \item \code{Spectra}, defined in the
 \href{https://bioconductor.org/packages/Spectra}{\emph{Spectra}} package.
+\item \code{MsExperiment}, defined in the
+\href{https://bioconductor.org/packages/MsExperiment}{\emph{MsExperiment}} package.
+\item \code{XcmsExperiment}, defined in the
+\href{https://bioconductor.org/packages/xcms}{\emph{xcms}} package.
 }
 
 In addition, the \emph{MsIO} package defines the \code{AlabasterParam} which can be
@@ -137,6 +159,16 @@ and an additional file (in HDF5 format) containing the data. See examples
 below for details.
 }
 
+\section{On-disk storage for \code{MsBackendMetaboLights} objects}{
+
+
+The \code{MsBackendMetaboLights} extends the \code{MsBackendMzR} backend and hence the
+same files are stored. When a \code{MsBackendMetaboLights} object is restored,
+the \code{mtbls_sync()} function is called to check for presence of all MS data
+files and, if missing, re-download them from the \emph{MetaboLights} repository
+(if parameter \code{offline = FALSE} is used).
+}
+
 \section{On-disk storage for \code{Spectra} objects}{
 
 
diff --git a/man/PlainTextParam.Rd b/man/PlainTextParam.Rd
index 501b901..2d42552 100644
--- a/man/PlainTextParam.Rd
+++ b/man/PlainTextParam.Rd
@@ -1,8 +1,9 @@
 % Generated by roxygen2: do not edit by hand
-% Please edit documentation in R/PlainTextParam.R, R/MsBackendMzR.R,
-%   R/MsExperiment.R, R/Spectra.R, R/XcmsExperiment.R
+% Please edit documentation in R/PlainTextParam.R, R/MsBackendMetaboLights.R,
+%   R/MsBackendMzR.R, R/MsExperiment.R, R/Spectra.R, R/XcmsExperiment.R
 \name{PlainTextParam}
 \alias{PlainTextParam}
+\alias{readMsObject,MsBackendMetaboLights,PlainTextParam-method}
 \alias{saveMsObject,MsBackendMzR,PlainTextParam-method}
 \alias{readMsObject,MsBackendMzR,PlainTextParam-method}
 \alias{saveMsObject,MsExperiment,PlainTextParam-method}
@@ -15,6 +16,8 @@
 \usage{
 PlainTextParam(path = tempdir())
 
+\S4method{readMsObject}{MsBackendMetaboLights,PlainTextParam}(object, param, offline = FALSE)
+
 \S4method{saveMsObject}{MsBackendMzR,PlainTextParam}(object, param)
 
 \S4method{readMsObject}{MsBackendMzR,PlainTextParam}(object, param, spectraPath = character())
@@ -43,6 +46,11 @@ are going to be stored/ should be loaded from. The default is
 and file name or directory to/from which the data object should be
 exported/imported.}
 
+\item{offline}{For \code{readMsObject()} to load MS data as a
+\code{MsBackendMetaboLights()}: \code{logical(1)} to evaluate \strong{only} the local
+file cache. Thus \code{offline = TRUE} does not need an active internet
+connection, but fails if one of more files are not cached locally.}
+
 \item{spectraPath}{For \code{readMsObject()}: \code{character(1)} optionally allowing
 to define the (absolute) path where the spectra files (\emph{data storage
 files}) can be found. This parameter is used for \code{MsBackendMzR} (see
@@ -78,13 +86,16 @@ The MS object currently supported for import and export with this parameter
 are:
 \itemize{
 \item \code{MsBackendMzR} object, defined in the
-(\href{https://bioconductor.org/packages/Spectra}{Spectra}) package.
+\href{https://bioconductor.org/packages/Spectra}{\emph{Spectra}} package.
+\item \code{MsBackendMetaboLights} object, defined in the
+\href{https://bioconductor.org/packages/MsBackendMetaboLights}{\emph{MsBackendMetaboLights}}
+package.
 \item \code{Spectra} object, defined in the
-(\href{https://bioconductor.org/packages/Spectra}{Spectra}) package.
+\href{https://bioconductor.org/packages/Spectra}{\emph{Spectra}} package.
 \item \code{MsExperiment} object, defined in the
-(\href{https://bioconductor.org/packages/MsExperiment}{MsExperiment}) package.
+\href{https://bioconductor.org/packages/MsExperiment}{\emph{MsExperiment}} package.
 \item \code{XcmsExperiment} object, defined in the
-(\href{https://bioconductor.org/packages/xcms}{xcms}) package.
+\href{https://bioconductor.org/packages/xcms}{\emph{xcms}} package.
 }
 
 See their respective section below for details and formats of the
@@ -102,6 +113,15 @@ corresponds to a spectrum with its respective metadata in the columns.
 }
 }
 
+\section{On-disk storage for \code{MsBackendMetaboLights} objects}{
+
+
+The \code{MsBackendMetaboLights} extends the \code{MsBackendMzR} backend and hence the
+same files are stored. When a \code{MsBackendMetaboLights} object is restored,
+the \code{mtbls_sync()} function is called to check for presence of all MS data
+files and, if missing, re-download them from the \emph{MetaboLights} repository.
+}
+
 \section{On-disk storage for \code{Spectra} objects}{
 
 
diff --git a/tests/testthat/test_MsBackendMetaboLights.R b/tests/testthat/test_MsBackendMetaboLights.R
new file mode 100644
index 0000000..ae4cc60
--- /dev/null
+++ b/tests/testthat/test_MsBackendMetaboLights.R
@@ -0,0 +1,94 @@
+## Tests for the MsBackendMetaboLights backend.
+
+library(Spectra)
+library(MsBackendMetaboLights)
+
+be_mtbls <- backendInitialize(MsBackendMetaboLights(), mtblsId = "MTBLS39",
+                              filePattern = "63A.cdf", offline = FALSE)
+
+test_that("readMsObject,PlainTextParam,MsBackendMetaboLights works", {
+    pth <- file.path(tempdir(), "test_backend_ml")
+    saveMsObject(be_mtbls, PlainTextParam(pth))
+
+    ## read
+    res <- readMsObject(MsBackendMetaboLights(), PlainTextParam(pth),
+                        offline = TRUE)
+    expect_true(validObject(res))
+    expect_equal(rtime(be_mtbls), rtime(res))
+    expect_equal(mz(be_mtbls), mz(res))
+
+    ## Clean cache first to check errors etc.
+    bfc <- BiocFileCache::BiocFileCache()
+    BiocFileCache::cleanbfc(bfc, days = -10, ask = FALSE)
+
+    ## read again offline throws error
+    expect_error(readMsObject(MsBackendMetaboLights(), PlainTextParam(pth),
+                              offline = TRUE), "No locally cached")
+
+    ## read re-downloading the data
+    res <- readMsObject(MsBackendMetaboLights(), PlainTextParam(pth),
+                        offline = FALSE)
+    expect_true(validObject(res))
+    expect_equal(rtime(be_mtbls), rtime(res))
+    expect_equal(mz(be_mtbls), mz(res))
+
+    unlink(pth, recursive = TRUE)
+})
+
+test_that("saveObject,readObject,MsBackendMetaboLights works", {
+    b <- be_mtbls
+    pth <- file.path(tempdir(), "save_object_ms_backend_metabo_lights")
+    saveObject(b, pth)
+    res <- dir(pth)
+    expect_true(length(res) > 0)
+    expect_true(all(c("OBJECT", "spectra_data", "peaks_variables") %in% res))
+    res <- readObject(pth, offline = TRUE)
+    expect_true(validObject(res))
+    expect_equal(rtime(res), rtime(b))
+    expect_equal(mz(res[1:10]), mz(b[1:10]))
+    ## Clear cache and repeat, syncing the data
+    bfc <- BiocFileCache::BiocFileCache()
+    BiocFileCache::cleanbfc(bfc, days = -10, ask = FALSE)
+    res <- readObject(pth)
+    expect_true(validObject(res))
+    expect_equal(rtime(res), rtime(b))
+    expect_equal(mz(res[1:10]), mz(b[1:10]))
+
+    ## readAlabasterMsBackendMzR
+    expect_error(readAlabasterMsBackendMetaboLights("some_path"),
+                 "required file/directory")
+    res <- readAlabasterMsBackendMetaboLights(pth, offline = TRUE)
+    expect_s4_class(res, "MsBackendMetaboLights")
+    expect_equal(length(b), length(res))
+    expect_true(validObject(res))
+
+    ## package Spectra not available:
+    with_mock(
+        "MsIO:::.is_spectra_installed" = function() FALSE,
+        expect_error(MsIO:::readAlabasterMsBackendMetaboLights(pth),
+                     "package 'Spectra'")
+    )
+    ## package Spectra not available:
+    with_mock(
+        "MsIO:::.is_ms_backend_metabo_lights_installed" = function() FALSE,
+        expect_error(MsIO:::readAlabasterMsBackendMetaboLights(pth),
+                     "package 'MsBackendMetaboLights'")
+    )
+    unlink(pth, recursive = TRUE)
+})
+
+test_that("saveMsObject,readMsObject,MsBackendMetaboLights works", {
+    b <- be_mtbls
+    pth <- file.path(tempdir(), "save_object_ms_backend_metabo_lights")
+    prm <- AlabasterParam(pth)
+    saveMsObject(b, param = prm)
+    expect_error(saveMsObject(b, param = prm), "Overwriting or")
+
+    res <- readMsObject(MsBackendMetaboLights(), prm, offline = TRUE)
+    expect_s4_class(res, "MsBackendMetaboLights")
+    expect_equal(length(b), length(res))
+    expect_true(validObject(res))
+    expect_equal(mz(res[1:10]), mz(b[1:10]))
+
+    unlink(pth, recursive = TRUE)
+})
diff --git a/tests/testthat/test_MsBackendMzR.R b/tests/testthat/test_MsBackendMzR.R
index 11597a7..2f78865 100644
--- a/tests/testthat/test_MsBackendMzR.R
+++ b/tests/testthat/test_MsBackendMzR.R
@@ -64,6 +64,12 @@ test_that("saveMsObject,readMsObject,PlainTextParam,MsBackendMzR works", {
 test_that("saveObject,readObject,MsBackendMzR works", {
     b <- sciex_mzr
     pth <- file.path(tempdir(), "save_object_ms_backend_mz_r")
+    .save_object_spectra_data(b, pth, object = "some_object")
+    res <- dir(pth)
+    expect_true(length(res) > 0)
+    expect_true(all(c("OBJECT", "spectra_data", "peaks_variables") %in% res))
+
+    unlink(pth, recursive = TRUE)
     saveObject(b, pth)
     res <- dir(pth)
     expect_true(length(res) > 0)