def parse_host_genus(data_dict):
    """Retrieve host_genus from PhagesDB.

    :param data_dict: Dictionary of data retrieved from PhagesDB.
    :type data_dict: dict
    :returns: Host genus of the phage.
    :rtype: str
    """
    try:
        host_genus = data_dict['isolation_host']['genus']
    except:
        host_genus = ''
    return host_genus
